Question about cylinder heads to the engine guru's

**William C.** · September 8, 2013, 03:35 PM

Re: Question about cylinder heads to the engine guru's

The 461X casting used in 1962 is generally considered to flow the best. At least that was the answer when I was racing Jr Stock NHRA back in the day...

**Duke W.** · September 9, 2013, 11:51 AM

Re: Question about cylinder heads to the engine guru's

I've got a pretty good library of measured flow data for both "stock" and "massaged" heads. Unfortunately, they are all 461 and 462. The best is a set of 462s with 1.94/1.50" valves that the owner went through three iterations of massaging and testing at the end of each iteration to get the final numbers.

Unfortunately I don't have any data for either unmodfied or massaged 461X heads, but they do have somewhat larger port volumes - 170-175cc versus 160-165cc for later "big port" small block heads, depending on who you want to believe.

Back in the seventies a buddy who was involved in sprint car racing said many preferred starting off with a set of 461X heads even after GM began offering the off-road heads. The story was that the 461X material had higher nickel content that made the heads tougher and more resistant to cracking, and everyone knew how to port them for maximum flow being as how guys had been modifiying them for over ten years.

Bottom line is I agree with Clup, the 461X is the best head to start with. Look at what NHRA allows in terms of valve seating - multi or single angle - you may have some latitude there. My understanding is that the OE chamber size is 60-61cc, so I'm surprised that they list 62.2. Usually they allow a little less than typical OE chamber volume to allow a cleanup cut on the head.

If it's legal, retard the Duntov cam at least four degrees, and use the second design '66-up valve springs -3811068/Sealed Power VS677. Set the valve lash at .008./.016" cold. With headers and open exhaust it should make power to the valve float speed of about 7200. If you can use any "single spring w/ damper" then the 3927142 spring that was designed for the Trans-Am racing cams will increase valve float speed to about 8000.

Assuming you aren't concerned with a numbers matching block, shave the decks to achieve minimum allowable deck clearance. If I'm reading the data right the minimum allowable deck clearance is only .002" versus OE nominal of .025" and most Flint machined heads are high. Could this be a misprint?

Shave the heads to achieve minimum allowable chamber volume, and use the thinnest head gasket you can get away with. I'm not aware that an OE equivalent .018" gasket is available, but the FelPro 1094 is .015". The next thicker one I know of is the Victor Reinz 1178SB, which is .020" stainless steel. All of the above will get the compression ratio up to about 12:1 and you will need to run race gas or avgas.

The reason a "stock" NHRA '69 Z-28 Camaro can run mid twelves versus low fifteens for a showroom stock version is allowable engine blueprinting, headers and open exhaust, slicks, 5.38:1 gears, minimum weight, and allowable chassis modifications like shocks to keep the front end up at launch for rear weight transfer and control axle hop and tramp.

Are aftermarket rods allowed? The OE '62 rods are a disaster waiting to happen. If aftermarket rods are not allowed at least use the second design 327 rods, and do full race prep on them, if allowed. Hopefully NHRA allows some latitude here. Better rods won't affect power, but they will have a huge positive impact on durability and allow the engine to live through hundreds or passes as long as you don't miss to many shifts.

BTW, wicked looking car! Keep us informed of how it goes, but be aware that a lot of guys are probably cheating in one way or another.

Duke

**Tim S.** · September 9, 2013, 12:54 PM

Re: Question about cylinder heads to the engine guru's

Duke,

The only 2 things that are monitored with the camshaft is lift and duration. Nothing is mentioned about where that cam is placed nor any mention of changing lobe centerlines. I cannot use any sort of roller rocker nor stud girdle.

I am allowed 1.5 additional points of compression over advertised. That would give me a max of 12.75 :1. Yeah, this is going to be a race gas engine. I am giving a little consideration to an oxygenated fuel like VP Race Fuels C-16. I am going to have to work on the air/fuel ratios on the dyno if I go that route.

I can use an aftermarket connecting rod so long as it is not aluminum or considered to be a lightweight rod (read titanium). I also cannot use an aluminum flywheel. There is no mention of the nodular iron unit being illegal. Trying to launch the car on a 6.70X15 tire could be tricky with a stock weight flywheel. The ring sizes are regulated but make no mention of a trick ring package to reduce internal friction. I suppose the bearing clearances will be on the loose side. In fact, there is a fellow that is big with HEMI's and his car (purpose built) will make 5lb's of oil pressure at a hot idle.

I have to do some math on tire roll out over 1320 ft to determine the best rear gear ratio. It seems to me a 4.11 will be the best. A 4.56 may be too much. I am going to use a wide ratio Muncie.

I am limited to the stock exhaust manifold's that are unported. I am allowed a dual exhaust system up to 2.5" pipes with an allowance for an H or X pipe. Full exhaust is manditory.

The idea for this sort of thing is appealing for 2 reasons. First, I am getting a little stale on the car show thing (lawn chair nationals). Secondly, The more I looked into this sort of racing, Hardly ever would you find a C1. I restored this car with my Dad 20+ years ago and I purchased it from him a few months ago. There is not one number in it that is right thus, the perfect candidate to go drag racing. I had considered vintage road racing (with some friends of mine) but, that is out of my budget.

I'll start a thread soon here on the car and what I do. I have purchased an F.I. unit & I have the wide wheels with pizza cutter Firestone's (6.70 x 15). The engine builder I use is an old Super Stock / Comp Eliminator guy. This should be a hoot on a budget.

I suspect a resonable goal would be low 13's after all is sorted out. Given the small tire and reasonalbe horsepower levels, this should be a fun car that does not break (much).

Thanks for the feedback on the heads (you too Bill!) Luckly, I have a set of 461x's. A real good valve job should get is done.

Thanks,

Tim

**William C.** · September 9, 2013, 01:29 PM

Re: Question about cylinder heads to the engine guru's

The JR stock racers can put you onto some very good cams that "meet" the original specs. I had one in my '65 for a while (30-30 cam) Made lots of HP but essentially undrivable, other than at the dragstrip...

**Duke W.** · September 9, 2013, 02:42 PM

Re: Question about cylinder heads to the engine guru's

If you're limited to manifolds and 2.5" pipes with some kind of muffler then 7000 will probably be maximum useable revs before the power falls off lower than 5500 in the next gear, which is where revs pick up shifting at 7000. You should reconsider the WR trans. The problem is when you shift into fourth at 7000 revs drop all the way off to about 4800 assuming a 1.46 third gear. So you could be half a fender length ahead at the half-way point and lose in the last half.

The power curve should be very flat - nearly constant - from 5500 to 7000 and this will likely be the range with the best AVERAGE power, which is where you need to run the engine. With 6.70-15 tires (760 revs/mile) 7000 yields about 120 with a 4.56, and I don't think your power to weight ratio will be good for more than about 110, so you could even consider 4.88s. A CR trans with a 4.56 yields about 10:1 overall in first, so you probably will have to do a fairly low rev launch, but that will save the drivetrain.

What are Firestone 6.70-15 pizza cutters?

Tires are critical, and you can probably find out what all the hot shoes run on old Chevy 15-inch wheel door slammers from the era by walking around the paddock. The good news is that tire traction limitations will help keep the drivetrain from getting torn up.

The Eagle SIR 5700 rods will be fine and meet the rules. You might also consider floating pins since the engine will need to be torn down for inspection once in a while. Assuming you don't have to run "stock" pistons check with the usual suspects on a semi-custom forged piston that have smaller skirts. Install low tension cast iron rings - 1/16", if allowable rather than the OE 5/32". It will use some oil, but since about 80 percent of internal engine friction is rings/pistons there is some power to be gained here. Main clearance in the range of .0015-.0020" and rods at .0020-0025" should give miniumum friction at the modest rev level you are turning, and use the OE oil pump with the OE 40-45 psi spring.

If it's legal run the 18-pound L-88 flywheel.

You should look at the rear suspension and possibly replace the spring hanger and radius rod bushings with harder rubber or urethane, which will help mitigate axle hop/tramp due to axle windup that can really kill your launch even with modest traction tires. Anyone with a '55-'57 Chevy has probably figured this out. Never feel guilty about copying anything that the fastest guys have done. There's no point in reinventing the wheel!

...sounds like a fun project - a lot cheaper than road racing - and if you build the engine properly and get a decent tire suspension setup it should be pretty reliable and provide years of running a few events per year without tearing it up all the time.

Duke

**Tim S.** · September 9, 2013, 03:18 PM

Re: Question about cylinder heads to the engine guru's

What are Firestone 6.70-15 pizza cutters?

Just my lingo for REALLY skinny tires. I have the Coker 6.70-15 repop tires

**Stuart F.** · September 9, 2013, 03:32 PM

Re: Question about cylinder heads to the engine guru's

Boy! this kind of talk gets me excited! I could get out my old notes, but by the time I find them you'll be well on your way. I'd say off hand that your estimate of low 13's is conservative. My 57 Bel Air post 292 C.I. ran low 13's with ease at around 106 mph. Of course, back in my day, we could run 2 sizes over on rear tires. We were some of the first to play around with weight transfer and got to the point where we came close to lifting the front wheels off. We went through a learning curve though which included loosing a drive shaft at over 100 mph due to U joint bind with our rear end lowering method. I tried F.I., but found dual WCFB's with three stage progressive linkage easier to manage the torque (wheel spin) off the line. Jetting them up more than made them equal with the F.I. at top end. When we ran a special top speed competition, I would sneak on a set of Caddy Eldo Quads w/ adapters, but I had to be careful with the 2 stage progressive off the line. The extra torque could bring on wheel hop and a sure bet to break a rotor (ignition, that is - don't ask me why - may have been something to do with the 4 point engine mounts). BTW, go with the softest clutch you can use - no BW coil springs. I used an 11" truck diaphragm pressure plate with driven discs with a lots of metallic in them (great for power shifting - and you will need to do that if you want to win - better have a scatter shield if you want to keep your feet. C1's are bad that way).

Good luck and have fun. I sure did until Uncle came calling (1961)

Stu Fox

**Tim S.** · September 9, 2013, 04:07 PM

Re: Question about cylinder heads to the engine guru's

If it's legal run the 18-pound L-88 flywheel.

That was my thought. It would knock down the inertia and it would allow me to try to "walk" the car out of the hole and not shock the suspension and tires as much. You bring up a good point on the CR as opposed to the WR trans. Coincidentally enough, I do have a 4.56 3rd member at my disposal.

I have a used Mcleod dual disc clutch that has a moderate friction material. With that, I should be able to manage some slippage for traction. With any sort of ceramic clutch material,I feel it would be just like a light switch. I do have an old C1 scattershield from Ansen. The damn thing weighs 60lbs.

A while back, I did see a company that was making a mono leaf rear spring for the C1 cars. I have become particularly fond of the mono leafs in my 67 Nova with 500 rwhp. Even with a 235-60 drag radial, the suspension hooks really well. If I can subdue the tire slippage, I can manage the axle tramp. I will be in the market for aftermarket axles as a precaution.

Duke and Stu, I think you guys are spot on with your points about suspension. I am going to have to do a little research in order to see what I can do with the front in order to get it to rise with relative ease. The rules detail the car must sit at stock ride height and no trick parts with the sway bar connected. If I took a spray bomb to some 90/10 shocks I can hide all of those. It is my understanding too that some of the experienced guys in this class run tire pressures around 10-12 lbs. In theory, I should be able to get the car to work reasonably well.

I elected to go the L84 route (beyond it just being cool) was due to the abilty for ram air / fresh air induction. I do not have a lot of faith in the L76 air cleaner in a C1. IMO, those may work well on a Corvair, not a Corvette. It would be much cheaper to go the L76 route.

Deep down, I would have to agree with you Stu about ET's. I just hate to over predict and under deliver.

**Tim S.** · September 9, 2013, 04:15 PM

Re: Question about cylinder heads to the engine guru's

Considering the fact some of you have taken an interest in what I am doing, you may have a few "suggestions" after reading the rules. I will post both rule packages both sanctioning bodies. Certainly, this is all for fun and to meet some more quality people.

This is from Pure Stock Muscle Car Drags.

Rules

The rules for 2010 will be posted once they are available.

The most important rule: Your musclecar must be stock, except for the modifications outlined below. If a modification is not mentioned, keep it original! Remember, the goal is to have fun drag racing your musclecar. See old friends, make new ones, and enjoy all the cool cars on the track!
For 1955 to 1974 musclecars built in United States and Canadian assembly plants with a minimum warranty of 12 months and 12,000 miles. Factory lightweight cars built for sanctioned drag racing and dealership-built/modified cars are not eligible to participate. Cars must be factory equipped with a minimum of four-barrel carburetion, dual exhaust, and other factory-installed equipment that promotes a high-performance intent and image. Cars are paired up based on time trial e.t.s and compete in a best-of-three heads-up shootout.
Body

The original appearance must be maintained. No aftermarket panels of any kind are allowed. No "custom" paint colors, designs, or lettering are allowed. The car must maintain the stock ride-height. Raising or lowering either the front or back of the car is NOT allowed. The car must have a presentable appearance. No primered areas, mismatched paint, or large rust-holes allowed.
Bumpers must retain all original bracing and reinforcements. Inner fender panels, front and rear, must be retained. Factory hood scoops, ram air, and fresh air induction must be correct for the year, make, and horsepower claimed. No aftermarket or homemade induction units of any kind are allowed.
Interior seating, trim, and materials must be correct for the year and model claimed, as well as being completely functional. Aftermarket tachs and gauges are allowed if mounted on the steering column or under the dash, except for some factory tachs mounted on top of the dashboard. All accessories must be functional (radio, wipers, heater, blower motor, turn signals, etc.). OEM glass only. All windows must be functional and closed during all runs.
The trunk must appear stock at all times.
Drivetrain

Automatic Transmissions: The transmission must be correct for the year, make, model, and horsepower claimed. Shift improver kits are allowed. Aftermarket shifters are not allowed. No manual valve bodies. Lightweight purpose-built, drag racing transmissions NOT allowed (for example Pro Trans, Kilgore, etc.). Just switching to aluminum drums is illegal. Anyone caught will be banned from the event until corrected! Torque converters must be within 1 inch of the stock outside diameter. Maximum stall limited to 2200 rpm. Higher stall speeds will require factory documentation.
Manual Transmissions: The transmission must be correct for year, make, model and engine of the car. 3-speed manuals may be upgraded to the correct 4-speed if originally available. Aftermarket H-pattern shifters are allowed if no modifications to the floorpan are necessary. Line locks are not allowed. Scattershields are okay. No conversions from column-shift to floor shift allowed unless available as a factory option. Aluminum flywheels are NOT allowed.
Rear Axles: The rear axle must be of the same manufacturer as the car. Any gear ratio is allowed. Lightweight driveshafts NOT allowed. Driveshaft safety loops are mandatory on all cars 13.99 and faster! Spools of any kind are NOT allowed.
Engine

Engine: Must be factory correct for the year, model, and horsepower claimed. Dealer-installed engines and dealer-performed engine modifications are not allowed. Casting numbers must be correct for the year and horsepower claimed including intake manifold, heads, and exhaust manifolds. Head modifications are prohibited, including, but not limited to, porting, bowl cutting, gasket matching, oversized valves, etc. Heads can be cut to help achieve the allowed compression over advertised. Blocks do not have to be "numbers matching," but they must be the correct displacement. Overbores up to .070" are allowed. Stock cranks only. NO strokers! Random P&G checks are possible. Lightweight cranks and connecting rods are NOT allowed. If found, you will be banned from the event until corrected! Aluminum rods are NOT allowed. Smaller-than-stock rod journals are NOT allowed. Aftermarket pistons are allowed, but piston rings can be no thinner than 1/16", 1/16", and 3/16" for top, second, and oil rings, respectively. Gas porting of pistons NOT allowed. Metric and pressure-back-type rings (dykes, head land, etc.) are NOT allowed. Torque straps allowed.
Compression Ratio Limits:

Engines with factory dished pistons will be allowed to run either a smaller dish, a flat-top piston, or a small domed piston to achieve the maximum allowed compression.
Engines with factory flat-top pistons will be allowed to run a domed piston to achieve the maximum allowed compression.
Engines with factory domed pistons must run a dome of equal or greater dome volume than stock to achieve the maximum allowed compression ratio.
Heads can be milled and blocks decked within reasonable limits in combination with a), b), or c) above to help achieve the maximum allowed compression ratio.

Electrical System: The battery must be retained in the original location and securely fastened down with the original style hold down. The charging system must be fully operational at all times. The removal of the alternator belt is not allowed. Lightweight batteries are NOT allowed.
Fuel System and Carburetor: The carburetor must be correct for the year, make, and horsepower claimed. Jetting and metering changes are permitted. THE CHOKE ASSEMBLY MUST BE IN PLACE AND FUNCTIONAL! Mechanical secondary carbs cannot be substituted if vacuum operated units were original to the car. Mechanical fuel pumps must be retained. Electric fuel pumps are NOT allowed. No fuel pressure gauges are allowed anywhere along the fuel system. Factory fuel lines are required and must be correct size. No rubber lines allowed unless originally equipped as such. No fuel cells are allowed.
Pulleys: All pulleys must be factory issue and be correct diameters for the year and horsepower claimed for the engine. Belts running the water pump, alternator, and power steering must be retained at all times. Air conditioning belts may be removed if they do not affect other components.
Valve Train: The valve train must be factory stock for the year, make, and horsepower claimed. Rocker arm ratio must be correct for the year and horsepower claimed. No aftermarket rocker arms of any kind allowed. Stock stamped steel or stock cast iron factory rocker arms only.Maximum valve spring SEAT pressure allowed is 130 pounds. Higher seat pressure will require factory documentation. Factory spring configuration must be retained; that is, if your car came with single valve springs, you must run single springs. If it came with dual valve springs, you must run duals. Beehive valve springs are NOT allowed. No aluminum or titanium valve spring retainers allowed.
Camshaft: The camshaft must be correct for the year, model, and horsepower claimed for the type of lifter (hydraulic or solid). Roller cams NOT allowed. Duration at .050" lobe lift must be within 1% of factory specs. Lift at the valve must be within 2% of factory specs. Engines must be able to produce at least 16.0 inches of vacuum at 1200 rpm. However, some factory-produced engines were not able to generate 16.0 inches in showroom condition, so those cars will be given a variance to the rule. Solid-lifter cams lift checked at zero lash.
Exhaust: Cast-iron exhaust manifolds are mandatory and must be correct for the year, model, and horsepower claimed. Internal modifications to the exhaust manifolds are NOT allowed. Under no circumstances will headers be allowed, including those cars that came with headers delivered in the trunk. The exhaust system may be upgraded to a maximum of 2.5-inch head and tail pipes. Pipes must be routed as they were originally for the year, make, model, and engine combination. Mufflers must be stock looking in design, that is, oval in shape. No glasspacks or straight pipes allowed unless installed as original equipment. Maximum muffler inlet and outlet size is 2.5 inches. X & H pipes allowed.
Ignition System: The ignition system must be stock, including the distributor, cap, coil, and wires. Points may be replaced with any electronic conversion that fits under the stock distributor cap. Replacement coils are allowed as long as they are the correct shape, color, and size. Coils must be mounted in the correct location with correct brackets for the make, year, and engine combination. We will no longer allow the use of aftermarket ignition boxes like MSD, Crane, Jacobs, etc. We made this decision based on participants using these ignition boxes for traction and total timing manipulation while making runs. You will be allowed to use a rev limiter, but the unit must be only a rev limiter and nothing else. Spark plug wires must be of correct appearance in size and color for the vehicle.
Cooling System: The radiator must be correct for the year, make, model, and horsepower claimed. No lightweight, aluminum radiators allowed. Overflow catch cans of at least 16 ounces are required. Radiator shrouds must be correct for the application. The fan must be factory original and correct for the year, model, and horsepower claimed. Aftermarket "lightweight" flex-fans are NOT allowed.
Suspension

Front Suspension: Stock springs and shocks must be retained. Drag race style springs, shocks, and bushings that allow excessive lift during launches are NOT allowed. The front sway bar must be retained, and it must be functional at all times. Raising or lowering of the front end is not allowed.
Rear Suspension: Stock springs and shocks must be retained. Traction devices are limited to hop-stop bars for the upper control arms on coil-spring cars. Pinion snubbers and clamping of springs are allowed on leaf-spring cars. No slapper bars or ladder bars of any kind allowed unless originally equipped from the factory. Factory documentation will be required to prove authenticity for any car equipped with bolt-on traction devices. No dealer-installed traction devices allowed. Aftermarket upper and lower control arms for coil-spring cars are not allowed. Raising or lowering of the rear end is not allowed.
Tires and Wheels: Reproduction tires or radial tires only. No soft compound tires of any kind allowed. Retread tires are not allowed. Use of traction compounds or rubber-softening chemicals on tires is strictly prohibited. Suspicious tires will be durometered. You are allowed to run tires one size over stock, with G70s being the largest size allowed for cars with 70-series tires, and G60s the largest allowed for cars that came with 60-series tires. All four tires must be the same size. No 60-series tires will be allowed unless they were originally available for the car's year and model. 60-series tires must be run on 15-inch rims as they were originally. Cars built before the introduction of 70-series Polyglas or Wide Ovals are allowed to upgrade to 70-series of appropriate size. Factory wheels only. Wheels must be correct in size, offset, and style for the car's make, model, and year. All four wheels must be the same size and offset.
Excessively worn or bald tires are strictly prohibited! TIRES CANNOT BE WORN DOWN TO THE TREAD WEAR BAR INDICATORS.

Suspected Violations, Required Tear Downs, and Banning from Race

Safety

Drivers must wear long pants. Cars 13.99 and quicker must have an approved Snell 2005 helmet! (This is an NHRA rule, and the track will enforce it. Update your helmet or the track will ban you from racing.) Batteries must be secured down. All cars must have seatbelts for the driver. All wheelstuds must be present and lugnuts tight. Radiators must have an overflow catch can of at least 16 ounces. All accessory belts MUST be in place and tight to operate the water pump, alternator, and power steering (A/C belt may be removed). Cars 13.99 and quicker must have a driveshaft safety loop! We highly recommend carrying a fire extinguisher in your car at all times. No passengers allowed in participating vehicles.
Attention: Please Read

No passengers allowed in participating vehicles.
Wristbands for drivers mandatory.
Guest driver wristbands mandatory.
If you run faster than 3/10 during shoot-outs, you forfeit the shoot-out.

Any questions or concerns, e-mail us.

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**Tim S.** · September 9, 2013, 04:20 PM

62 Pure Stock Drag Racing Build Thread

And here is the Super Car Races rule set (Very similar) Official SuperCar Races Stock Rules SuperCars Philosophy:S- Showcase All that participate in the SuperCar ShootOut U- Unite and make friendships that last a lifetime P- Persevere to be the best E- Empower others to act with integrity R- Reward all accomplishments big and small C- Celebrate Victories A- Actively participate in giving back to the community R- Respect and treat everyone like they're one of us

The Participants, Sponsors and Fans of Supercar Races don't want to be known only as Musclecar enthusiasts, but want to be known as a group that gives back to the hobby and the community. We have championed many issues and are solidifying the SuperCar Series as the concrete foundation to the style of racing we enjoy most. We are excited to officially welcome Pure Stock into the SuperCar Family. We want to give our current and future Racers a venue to Showcase their Pure Stock MuscleCars. SuperCar Races prides itself on being the leader in American MuscleCar Racing. In 2011, We will be featuring a venue for all Legal Pure Stockers to take part in. Our Rules will be posted over the next couple of months. We are moving forward at a rapid but cautious pace. In the next couple of months, we will appoint a Rules Committee that will represent the majority of the Pure Stockers. Our Goal is to give the Pure Stock community a series of events to take part through out the season. This new series will enforce all rules with NO exceptions. Welcome Pure Stockers! SuperCar ShootOut 2011 & 2012 "Stock" Class Rules1.00 Body: 1.01 Original appearance must be maintained. No after-market panels of any kind are allowed. No "custom" paint colors, designs, or lettering are allowed. 1.02 Musclecar must maintain the stock ride-height. Raising or lowering either the front or the back of the car is not allowed. 1.03 Musclecar must have a presentable appearance. No primered areas, mismatched paint, or large rust-holes allowed. 1.04 Bumpers must retain all original bracing and reinforcements. Inner fender panels, front and rear, must be retained. 1.05 Factory hood scoops, ram air, and fresh air induction must be correct for the year, make, and horsepower claimed. No after-market or homemade induction units of any kind are allowed. 1.06 Factory air cleaner assembly and original size air filter must be retained and in place during all runs. No after-market air cleaners allowed. 1.07 Interior seating, trim, and materials must be correct for the year and model claimed and functional. After-market tachometers and gauges are allowed if mounted on the steering column or under the dash, except for some factory tachs mounted on top of the dashboard. OEM glass only. 1.08 All windows must be functional, made of original material. and closed during all runs. 1.09 All accessories must be functional: Radio, heater, blower motor, wipers, turn signals, lights, ETC. 1.10 The trunk area must appear stock at all times. 2.00 Engine: 2.01 Engine must be factory correct for the year, model, and horsepower claimed. 2.02 Dealer installed engines and dealer performed engine modifications are not allowed. 2.03 Casting numbers must be correct for the year and horsepower claimed, including: intake manifold, heads, and exhaust manifolds. No Modifications are allowed. 2.04 Blocks do not have to be "numbers-matching," but they must be the correct displacement. 2.05 Over bores up to .070" are allowed. 2.06 Stock cranks only. NO strokers! 2.07 No lightweight cranks, aftermarket cranks, or connecting rods allowed. Oil pan drain plug will be scoped on record runs 2.08 Pistons must be of the original design for the year and horsepower claimed. Replacement forged pistons are allowed. 2.09 Compression ratios limited to one and a half points (1.5) over factory advertised rating. Note a max compression limit of 13.0 to 1 is allowed. Musclecars delivered with higher compression may run factory advertised rating. Clarification- Compression is maxed out at 13.00 to 1, meaning with the 1.5 max you can only go to 13.00 to 1 as an overall max. If your car was delivered with 13.5 to 1 you can run 13.5 to 1, No higher. 2.10 Torque straps are allowed for safety reasons. 2.11 No after-market blocks allowed. Note, Carburetor, valve cover removal and P&G checks are mandatory once 12.49 E/T is achieved along with a complete mandatory certification. 3.00 Fuel System and Carburetor: 3.01 Carburetor must be correct for the year, make and horsepower claimed. Jetting and metering changes are permitted. Choke assembly must be functional. 3.02 Mechanical secondary carburetors cannot be substituted if vacuum operated units were original to the car. 3.03 Mechanical fuel pumps must be retained. 3.04 Electric fuel pumps are NOT allowed. 3.05 No fuel pressure gauges are allowed at anytime. 3.06 Factory fuel lines must be present and correct size are required. 3.07 Once 12.49 E/T is achieved, Spec fuel will/may be dispensed at the event with a max octane rating for compression allowed for said combination. Propylene Oxide, Nitro-methane, alcohol and nitro-propane are NOT allowed. 4.00 Exhaust: 4.01 Cast iron exhaust manifolds are mandatory and must be correct for the year, model and horsepower claimed. 4.02 NO internal modifications to the exhaust manifolds are allowed. 4.03 Under no circumstances will headers be allowed, including those cars that came with headers delivered in the trunk. 4.04 Exhaust system may be upgraded to a maximum of 2.5-inch head and tail pipes. Pipes must be routed as they were originally for the year, make, model, and engine combination. 4.05 Mufflers must be stock-looking in design, that is, oval in shape. No glasspacks or straight-through pipes allowed unless installed as original equipment. 4.06 Maximum muffler inlet and outlet size is 2.5 inches. 4.07 X Pipes and H Pipes allowed. 4.08 Exhaust must be to factory specs with a pipe diameter no larger than 2.5 inches unless delivered from the factory with a larger diameter 5.00 Camshaft: 5.01 Camshaft must be correct for the year, model, and horsepower claimed for duration, lift and type of lifter (hydraulic or solid). 5.02 No roller cams allowed. 5.03 Engines must be able to produce at least 16.0 inches of vacuum at 1200 rpm. If camshaft is still questioned, Engine idle noise level may be checked using Radio Shack Meter 33-2055 Set on Filter C, Slow response. Engine Idle will be measured @ 1000 RPM's in neutral or park, standing 3 Ft. away from the back bumper at waist height, the car in question must not exceed 100 Dba on the said meter. Note, Carburetor, valve cover removal, distributor removal and P&G checks are mandatory once 12.49 E/T is achieved along with a complete mandatory certification. 6.00 Valve Train: 6.01 Valve train must be factory stock for the year, make, and horsepower claimed. 6.02 Rocker arm ratio must be correct for the year and horsepower claimed. 6.03 Roller tip rockers are NOT allowed. 6.04 OEM-style replacement lifters only. 6.05 Poly-lock type adjustable nuts, jam (crimp) nuts, and adjustable pushrods are allowed. 6.06 Valve covers must be correct for the year, make, and horsepower claimed. 6.07 Maximum valve spring seat pressure allowed will be 130 psi. Note, Carburetor, valve cover removal and P&G checks are mandatory once 12.49 E/T is achieved along with a complete mandatory certification. 7.00 Pulleys: 7.01 Pulleys must be factory issue, and they must have the correct diameters for the year and horsepower claimed for the engine. Deep groove pulleys allowed ONLY if of the same diameter as original 7.02 Belts running the water pump, alternator, A/C and power steering must be retained at all times. No exceptions 8.00 Ignition System: 8.01 Ignition system must be stock, including the distributor, cap, coil, and wires. 8.02 Points may be replaced with any electronic conversion that fits under the stock distributor cap. 8.03 Replacement coils are allowed as long as they are the correct shape, color, and size. Coils must be mounted in the correct location with correct brackets for the make, year, and engine combination. 8.04 Spark plug wires must be of correct appearance in size and color for the vehicle. 8.05 Ignition boxes allowed for ignition and rev. limiter purposes only up to 12.49 E/T. 8.06 Ignition boxes must be hidden to maintain stock appearance under hood. 8.07 Once you run 12.49 or quicker you must go back to a factory original ignition system 8.08 Musclecars may change to an under the distributor cap rev limiter like Crane, Accel, or approved stand-alones like MSD 8728, Pertronics 600, Davis Unifires Ignitions 380777, Autometer 5301. Note After market ignition boxes and aftermarket coils are allowed up to a 12.49 E/T and are limited to factory sealed MSD 6 and 6AL. Data recording devices are not allowed. 9.00 Cooling System: 9.01 Radiator must be correct for the year, make, model, and horsepower claimed. 9.02 No lightweight, aluminum radiators allowed. 9.03 Overflow catch cans of at least 16 ounces are required. 9.04 Radiator shrouds must be correct for the application. 9.05 Fan must be factory original and correct for the year, model, and horsepower claimed. No after-market "lightweight" flex-fans allowed. 10.00 Electrical System: 10.01 Battery must be retained in the original location and securely fastened down with the original style hold down. 10.02 Charging system must be fully operational at all times. The removal of the alternator belt is not allowed. 10.03 Lightweight batteries are not allowed. 11.00 Drivetrain: 11.02 Shift improver kits are allowed. Aftermarket shifters are not allowed, with the exception of an after-market H-pattern shifters, if no modifications to the floorpan are necessary. 11.03 No manual valve bodies. 11.04 No lightweight purpose-built drag racing transmissions allowed. 11.05 Manual Transmissions: The transmission must be correct for the year, make, and horsepower claimed. 11.06 Line locks are allowed. All wires and unit must be hidden, no exceptions. 11.07 Scattershields are allowed. 11.08 No conversions from column-shift to floor shift allowed unless available as a factory option. 12.00 Rear Axles: 12.01 Rear axle must be of the same manufacturer as the car and originally available with the transmission and engine combo. Note, no gun drilled light weight axles, no lightened ring gears, no spools, no aluminum driveshafts. 12.02 Any gear ratio is allowed. 12.03 Driveshaft safety loops are mandatory on all cars 13.99 and faster. 13.00 Suspension: 13.01 Front stock springs and shocks must be retained. Drag springs and shocks are NOT allowed. 13.02 Front sway bar must be retained, and it must be functional at all times. 13.03 Rear suspension traction devices are limited to hop-stop bars for the upper control arms on coil-spring cars. Rear shocks, stock replacement type only. 13.04 Factory pinion snubbers and clamping of springs are allowed on leaf-spring cars. 13.05 No slapper bars or ladder bars of any kind are allowed unless originally equipped at the factory. Factory documentation will be required to prove authenticity for any car equipped with bolt-on traction devices. 13.06 No dealer-installed traction devices allowed. 13.07 After-market upper and lower control arms for coil spring cars are not allowed. 13.08 Stock ride height must be retained at all times. 13.09 Leaf springs must be same amount as stock, using correct materials. 14.00 Tires, Wheels & Brakes: 14.01 Reproduction tires or radial tires only. 14.02 No soft compound tires of any kind allowed. 14.03 Retread tires are not allowed. 14.05 Tire size must approximate what was originally installed on the car. All four tires must be the same size. 14.07 Musclecars built before the introduction of 70-series are allowed to upgrade to 70-series tires of appropriate size for the car. Please Call, PM or E-mail for clarification. 14.08 Factory wheels only. Wheels must be correct in size, offset, and style for the car's make, model, and year. 14.09 All four wheels must be the same size, offset and must be of correct material. 14.10 Tire Tech: All the repop tire treads are similar in design, 4-6 deep circular tread grooves with smaller grooves and sipes within those rows. There must be evidence of the original main tread grooves over the whole tire to be legal. Any bald sections or patches where the original main groove disappears and the tire must be replaced. Most important if your tires are questionable, make sure you bring an extra set with you to qualify and compete. Tires will be inspected before during and after the event is completed and must have all of the main treads showing. Tread/rubber softener treatment not allowed. A durometer test will be done to compare tire softness to manufactured specs. 14.11 Factory OEM Brakes ONLY. 15.00 TRACK TECH: 15.01 All track safety rules apply and you must pass track tech. When required by track safety rules, roll bars and aftermarket seat belts will not be cause for disqualification. 16.00 Certification: 16.01 Certification may include but is not limited to inspection or removal of the following- Carburetor, Cylinder Head Removal, Check CC Heads, Piston Inspection, scope through the oil drain plug, Valve cover removal, coil inspection, Distributor removal, torque converter inspection. P&G checks are mandatory once 12.49 E/T is achieved along with a complete mandatory certification. Once 11.99 E/T is achieved, exhaust must be to factory specs with a pipe diameter no larger than 2.5 inches unless delivered from the factory with a larger diameter. Musclecars may ask for Certification at any E/T. Certification may be done ahead of time, Contact Ralph Barbagallo to schedule an appointment. 17.00 BANNED FOR LIFE: 17.01 Nitrous, traction control, Data recording devices are not allowed. If caught with any of the above mentioned, you will be banned for life. 18.00 BEST 2 OUT OF 3 SHOOTOUT: 18.01 Entire field runs Heads-up 2 out of 3 Match Race. .500 pro tree, First round lane choice is awarded to the car with the quicker qualifying ET. Racers must alternate lanes in all subsequent rounds. .400* break out rule. *Break out rule of .400 in affect in all 2 out of 3 Match Races. If competitor runs .400 quicker in competition than the qualified E/T, The competitor will forfeit all rounds of competition. Official SuperCar Races "Stock" Class Rules Committee

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**Duke W.** · September 9, 2013, 08:56 PM

Re: 62 Pure Stock Drag Racing Build Thread

My thoughts:

1. Definitely talk to the piston manufacturers like JE, Aries, etc. about short skirt, low friction forged pistons, and 1/16" rings are legal. Shoot for .010 deck clearance with the .022 Victor Reinz gasket that will give you .032" quench clearance. That's a little less than Chevrolet's .035" minimum, but many drag racers have run a lot less than that. Get enough piston dome to achieve about 12:1, true. Above that the dome volume can screw up combustion chamber geometry, so you get into diminishing, if not negative returns. It also appears that the .015" gasket may be legal, which will add a couple of tenths and bring quench clearance down to .025", which I think you can get away with without damage. You need to get very accurate measurements of your block deck height. Only remove enough material to be sure they are flat and equal side to side. Piston compression height can be specified to achieve target deck clearance.

2. You can definitely run 2.5" glass packs since this design was optional from the factory. Make sure they are the same length as the OE off-road mufflers, and you should be able to win any arguments.

3. It appears that you can run 70 series radials. Tires are such a wild card you need to check out what the hot shoes are running this week.

4. The ...142 single valve spring w/damper has less than 130 lbs. seat force, so it is legal. Use them, and I'm sure there is a Sealed Power/Speed Pro equivalent. This will give you more valve float margin in case you miss a shift.

5. Since it's legal to replace the points with an electronic switch, I recommend this. It will eliminate the frequent dwell/timing checks that are necessary on a race engine with points.

6. I don't have a lot of drag racing experience, but from what I've done the best way to launch with street tires is to drop the clutch and floor the throttle simlutaneously at about 2000 or whatever it takes to just "haze" the tires. Too hard a launch and they just light up and you go nowhere. With a close ratio trans and 4.56 you might even get away with 1500, and a properly set up FI system will be much less likely to "bog" than any carb setup. I don't think you need anything other than an OE equivalent clutch. The tires will have plenty of slip. With a set of light springs that gets all the advance in by 2500 the Duntov cam should have plenty of low end torque. For now I'd suggest installing it at the OE indexing, but get an adjustable timing set so you can retard it later on. It's best to start conservative and go from there. Any race car is needs some development runs to get it fully dialed in. There are opportunities to rephase the Duntov lobes for broader torque bandwidth though it's probably not strictly legal. We can discuss this privately.

7. Go ahead and install a driveshaft loop as you will no doubt be running less than 13.99 once you get the car and your driving technique dialed in.

8. The rules don't say much about rear suspension bushings, so make them as rigid as you can get away with, and your OE radius rods are definitely legal. Since OE replacement shocks are the "rule" they will probably be okay as long as you can minimize compliance in the rear suspension that allows axle windup that leads to hop/tramp.

9. A '62 FI Corvette is an excellent platform for this restrictive rule "pure stock" type drag racing - not too front heavy, decent Hotchkiss rear suspension with OE radius rods, and a GREAT ENGINE!!!

Duke

**Duke W.** · September 9, 2013, 11:14 PM

Re: Question about cylinder heads to the engine guru's

I have a late friend who drag raced a black '59 with an early 327 and "small plenun" FI system at the old Lyons drag strip - back in the early/mid sixties, before I knew him. I don't remember all the details, but it probably had head work. I think it had a stock short block with a Duntov cam. I know he ran in the 12s, and he claimed he shifted as high as 8000.

Alas, one of those early, weak 327 rods let go. It actually broke at idle and holed the block while he was driving home from the bar scene on a Saturday night. He sold the car.

It's too bad Jerry is no longer with us. He'd have a real interest in your project and could probably give some excellent advice based on real experience.

Duke

**Tim S.** · September 10, 2013, 07:12 AM

Re: Question about cylinder heads to the engine guru's

That is some great information Duke. It was just the type of feedback I was looking for. While the entire build may take a while, I will post some details here soon. I have plans of installing the F.I. unit on the car as it stands right now. Currently, the car has a 327-340hp with an LT1 cam and 9:1 compression. It also has a WR Muncie in it with 3.55 gears. It's a great road car to bang around in. The engine build, suspension mods, and detail work will come in some time.

I am really excited about this project but, need to finish up a couple of others I currently have burning.

Tim

**Jerry G.** · September 10, 2013, 10:47 AM

Re: Question about cylinder heads to the engine guru's

First, I applaud you using your Vette and having fun racing it.
Are you allowed to block off the heat riser passage in the head. I use furnace cement to close off this area and improve problems with the 3-5 heat buildup. I do road racing so this may not be a problem for drag racing.
Second and this ones for Duke i think, the question of using wide ratio vs CR transmission is one shaped by the peak torque point isn't it? If your shift point is 7000 RPM then you would want a gear split that brought you back to the peak torque point whether that a WR or CR box. This is a real question for me since I striped the teeth off my third gear at Monterey last month and I have to figure out what split is best for my engine.
Third there is a web site that has all the chevy heads numbers and what the maximum flow is out of them. It may not be representative since you aren't allowed to port your heads.
Are you allowed to relieve them? This is a BIG deal on stock heads. Jerry

Question about cylinder heads to the engine guru's

Question about cylinder heads to the engine guru's

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