Fuelie stroker engine cam selection

[Keith R.]

Here's my situation: I'm having an engine built for my 1960 Fuelie. The engine will be correct in appearance but it will have a 327 Stroker kit installed with roller tip rockers and solid lifters. Jack Podell, who sold me the fuel injection unit emphasizes that it is critical to have the correct cam in the engine. He advocates a 097 Duntov cam however I don't think that he knows that it will be a Stroker engine. The engine builder originally wanted to put a .30 - .30 cam in the engine but I was told that it would have too much of a loping idle and it may not pull enough manifold vacuum. He now suggests a E900P cam for this particular engine configuration although I'm told that this is just a 30-30 cam.

I've searched the archives and found comments from Duke Williams and John DeGregory who both had good advice (See 63 327 fulie motor; September 25, 2006) Duke suggested a LT-1 cam and John the Speed Pro CS 113R but I thought I'd ask the group if they have any other thoughts or recommendations. Thanks.

[Duke W.]

Re: Fuelie stroker engine cam selection

Assuming you are using the original heads, the LT-1 cam will produce the best combination of bottom end torque and top end power, but the key is head flow. The 30-30 cam will kill the low end torque with no significant increase at the top end.

Assuming you are using the OE heads, you need to massage the hell out of them, including increasing inlet valve size to 1.84", to even get OE 461 flow numbers, but this is the only way to get top end power - not some "magic camshaft". You should also open up the inlet manifold runners if you are looking for maximum top end power. Search the archives for "327 LT-1" to find out more information about this configuration including lab and chassis dyno tests.

When all the naysayers chime in, ask them for their system engineering analyses AND dyno results.

The LT-1 cam produces about the same manifold vacuum as the Duntov, so this is not an issue. The increase in displacement may be an issue, since, like a carburetor, the FI's idle fuel flow is based on manifold vacuum and engine displacement, but based on some experience I have system engineering "FI strokers" most FI systems can be "tuned" to the new displacement with the idle speed and mixture adjustement.

I can't think of a bigger waste of money than "roller tip rockers". They are the absolute worst junk ever perpetrated by the hot rod parts industry. Use all OE drivetrain components including ...068 or equivalent valve springs and you have an engine that can safely rev to 7000, but may not have enough head/manifold flow to make useable power that high. Don't spare the budget on head massaging and a modern set of connecting rods.

Unless you massage the heads, there is little point in running a mechanical lifter cam, because with the 3.25" stroke and small port heads the engine won't make useable power beyond about 5500 revs regardless of the cam. What you will basically have is a '63-'64 327/250 with an FI system, and attempts over the years to put "big cams" into 327/250s usually result in little top end power improvement while killing the bottom end torque. It's all about head flow!

Duke

P. S. One of my "327 LT-1" prototype owners has reported a valve train problem. Against my strong advise, he installed roller tip rockers - he got them for "free". Now they are coming back to haunt. The jury is still out, but an initial inspection of the worn pushrod points to a problem with the rocker arm. All the pushrods are original to the engine and had about 60K miles before the rebuild. All pushrods and rockers showed no signs of wear, and I recommended he reuse them as matched sets, but his decision to install the aftermarket rockers results in mismatched parts, and, unfortunately, he just threw the OE rockers in a bag, and there is no record of their matching pushrod. I can lead the horses to water, but it's up to them to take a drink!

It's all in the details. Details! Details! Details!

[Tom P.]

Re: Fuelie stroker engine cam selection

Well, I won't trade blows with Duke, BUUUUUUUUUUUUUUUUUT, here's what I'm running in the 56.
It is a .030 over SB400 (406ci)
Heads are 66 2.02 (462 castings) with mild port and bowl clean up.
Cam is hyd lifter, about .500 lift/235deg duration @ .050 lift (it's been ~10-12yrs since I built the engine and I forget the exact cam specs). Vacuum is a NON-issue for the FI unit. It has been my experience for many years that if the engine will produce ABOVE 11in vacuum at idle, the FI units will work fine.
Comp Cams roller tip rockers.
Flat top pistons (for pump gas compatability).
Rochester FI unit initially modified by Bill Thomas many years ago (plenum cut in half and hogged out) and various other later modifications by yours truly.
Screams like a scalded dog. ZERO problems.

http://www.youtube.com/watch?v=V1I9q3QAMac

Heads have additional bosses welded/drilled/tapped to accomodate early, staggered bolt pattern valve covers.

[Duke W.]

Re: Fuelie stroker engine cam selection

Nice engine compartment. How about getting some Dynojet pulls, so we can see what it really does.

Start the pulls at no more than 1500.

Did you buy an expensive "thin wall socket" for the rocker stud nuts since you can't get a regular socket on those POS Comp Cam roller tip rockers or grind down a standard wall thickness socket.

Duke

[Tom P.]

Re: Fuelie stroker engine cam selection

Nice engine compartment. How about getting some Dynojet pulls, so we can see what it really does.

Start the pulls at no more than 1500.

Did you buy an expensive "thin wall socket" for the rocker stud nuts since you can't get a regular socket on those POS Comp Cam roller tip rockers or grind down a standard wall thickness socket.

Duke

I have a cheapie, thin wall, deep socket that I came up with sometime back in the Civil War days (I have no clue where I got it).

[Stephen B.]

Re: Fuelie stroker engine cam selection

Tom
Thats one bad C-1 you've got. I too have used and will continue to use Comp Cam roller tip rockers in every Corvette and Street Rod I have.I also endorse anything that Comp Cam makes.Their tech line is great.I read a few years ago that 98% of the NASCAR teams used comp Cam products and 100% of the pro Stock.Perhaps Duke bought some cheap Chinese roller tips.Comp Cam products are made in America .I have never heard of a failure.
Stephen Barrett (21558)

[Joe C.]

Re: Fuelie stroker engine cam selection

These work:

[Dick W.]

Re: Fuelie stroker engine cam selection

Tom
Thats one bad C-1 you've got. I too have used and will continue to use Comp Cam roller tip rockers in every Corvette and Street Rod I have.I also endorse anything that Comp Cam makes.Their tech line is great.I read a few years ago that 98% of the NASCAR teams used comp Cam products and 100% of the pro Stock.Perhaps Duke bought some cheap Chinese roller tips.Comp Cam products are made in America .I have never heard of a failure.
Stephen Barrett (21558)

Years ago, failures with the rockers were common. Have you ever seen what a needle bearing will do to an oil pump? Hard to believe that they can work their way thru the oil pump screen. With that said, I have not heard of a failure of Crane or Competition roller rockers in quite a few years.

Being the old fossil I am, I had a set of Sharp roller rockers that I ran for many years on several different engines. Never a failure.

The rollers diminish the side loading on the valve stem when the valves operate, plus are a consistant ratio unlike conventional arms that will vary within sets. I always ran 1.6-1 rockers and could tell a small difference in performance. Like the 6.050 rods, made a difference also.

[Gene M.]

Re: Fuelie stroker engine cam selection

Frank Scriabica would always say not to deviate too much from the as delivered 327 and FI cam shaft. The cylinder head, compression and valve timing along with the engine displacement were a match as they were produced. The flow of everything is a good match. Any deviation and you are on your own...........

No dyno results here nor track times, just what the "Fuel Injection Master" said.

We do miss Frank.

[Keith R.]

Re: Fuelie stroker engine cam selection

Assuming you are using the original heads, the LT-1 cam will produce the best combination of bottom end torque and top end power, but the key is head flow. The 30-30 cam will kill the low end torque with no significant increase at the top end.

Assuming you are using the OE heads, you need to massage the hell out of them, including increasing inlet valve size to 1.84", to even get OE 461 flow numbers, but this is the only way to get top end power - not some "magic camshaft". You should also open up the inlet manifold runners if you are looking for maximum top end power. Search the archives for "327 LT-1" to find out more information about this configuration including lab and chassis dyno tests.

When all the naysayers chime in, ask them for their system engineering analyses AND dyno results.

The LT-1 cam produces about the same manifold vacuum as the Duntov, so this is not an issue. The increase in displacement may be an issue, since, like a carburetor, the FI's idle fuel flow is based on manifold vacuum and engine displacement, but based on some experience I have system engineering "FI strokers" most FI systems can be "tuned" to the new displacement with the idle speed and mixture adjustement.

I can't think of a bigger waste of money than "roller tip rockers". They are the absolute worst junk ever perpetrated by the hot rod parts industry. Use all OE drivetrain components including ...068 or equivalent valve springs and you have an engine that can safely rev to 7000, but may not have enough head/manifold flow to make useable power that high. Don't spare the budget on head massaging and a modern set of connecting rods.

Unless you massage the heads, there is little point in running a mechanical lifter cam, because with the 3.25" stroke and small port heads the engine won't make useable power beyond about 5500 revs regardless of the cam. What you will basically have is a '63-'64 327/250 with an FI system, and attempts over the years to put "big cams" into 327/250s usually result in little top end power improvement while killing the bottom end torque. It's all about head flow!

Duke

P. S. One of my "327 LT-1" prototype owners has reported a valve train problem. Against my strong advise, he installed roller tip rockers - he got them for "free". Now they are coming back to haunt. The jury is still out, but an initial inspection of the worn pushrod points to a problem with the rocker arm. All the pushrods are original to the engine and had about 60K miles before the rebuild. All pushrods and rockers showed no signs of wear, and I recommended he reuse them as matched sets, but his decision to install the aftermarket rockers results in mismatched parts, and, unfortunately, he just threw the OE rockers in a bag, and there is no record of their matching pushrod. I can lead the horses to water, but it's up to them to take a drink!

It's all in the details. Details! Details! Details!

Thanks Duke. As I said at the beginning of the thread, the engine builder advocates an Elgin 900-P which according to the manufacturer specs looks pretty much like an 097. Duration 228/230. lift .395/.401. lobe line 108/112. lash .012/.018. I also understand that the Speed Pro Federal Mogul C-113R cam that John DeGregory uses is a duplicate of the 097. Can you give me your perspective on the performance differences between these for use in a FI 327 Stroker? I appreciate your thoughts.

[Duke W.]

Re: Fuelie stroker engine cam selection

The Elgin specs match the Duntov, and the CS113R for sure is a Duntov, but for 327s I recommend the LT-1 cam (Speed Pro CS1145R available from NAPA).

I have the lobe lift data for all GM OE cams, and from this data I have done a dynamic analyses of all the OE cams to determine their velocity, acceleration, and jerk profiles.

The Duntov lobe is an old design that has symmetrical lobes, and though the accleration is mild, peak jerk occurs just above the tops of the clearance ramps, which is not good, especially if the the clearance is too loose. Jerk, which is the rate of change of acceleration, is related to shock loading. Think of hitting something with a hammer.

Beginning in the early sixties, several years after the Duntov was designed, Chevrolet began serious analysis of valve train dynamics with the Optron, which displayed valve motion on an oscilloscope. The first observed anamoly was the valve bouncing off the seat at high revs at closing. This led to the development of asymmetrical lobe where the closing is more gentle than the opening, and this will significantly mitigate or eliminate valve bounce for either mechanical or hydraullic lifter cams.

Later designs also reduced peak jerk and moved it farther above the tops of the clearance ramps. The result of all this is less loading on the valve train and valve seats. These are all very low level engineering details that you will never hear about from cam grinders or read about in hot rod magazines, but they are critical to valve train and valve longevity, which is why I only recommend OE cams, and the cams I designed all incorporate OE lobes designed not earlier than about 1963.

The Duntov and LT-1 cams have about the same effecive overlap, measured in sq-in-degs, eventhough the LT-1 cam has a much wider LSA. Effective overlap increases as duration is increased at the same LSA, so in order to maintain the same effective overlap with longer duration, the LSA must be increased. Both the Duntov and LT-1 cams pull about the same manifold vacuum at idle - about 12" at 900 on a 327.

The LT-1 cam has a bit too much duration for a 283, so I think the Duntov is an okay choice for a 283, but I have recommended that owners have Crane grind a custom version (They have Duntov lobe masters.) with POMLs of 110/118, which yields a LSA of 114 to cut down effective overlap, or alternatively, install a L-79 cam which is essentially a hydraulic lifter verison of these specs. Though the .050" durations of the Duntov are 228/231, part of this is clearance ramp, and the actual effective .050" durations - what you would use to compare to a hydraulic lifter cam are 220/220 versus the L-79 cam's 222/222 - essentially the same effective durations but the L-79 lobe has both higher lift and less harsh dynamics. This is what nearly a decade of serious engineering research on valve train dynamics yields!

Regarding "strokers" C. F. Taylor who ran the MIT/Sloan Automotive labs for many years and wrote a two-volume 1300 page textbook on IC engines that I consider "The Bible" developed a concept of "similar engines" as follows:

Two engines of different stroke that are otherwise identical will develop approximately the same peak power at the same mean piston speed. So merely stroking a 283 to 327 will not materially increase peak power, and this is born out in simulations and dyno tests.

Stroking will increase average torque and average power across the range, so there will be an improvement in overall performance. The engine will feel "torquier", but not want to rev as high.

In order to gain more peak power from stroking, inlet and induction flow must be improved, and the biggest bang for the buck is massaging the heads. More head flow will increase maximum potential power without much if any effect on peak or low end torque, so the combination of stroking and improved head flow improves torque/power across the rev range all the way to the maximum revs of the standard stroke engine.

Simulations and dyno tests of two "327 LT-1" engines proved that the LT-1 cam makes the broadest torque bandwidth of any OE cam - 80 percent of peak torque at 2000, which I consider a minimum for acceptable road engine performance and useable power to 7200.

Search the term and you will find all the results.

If you configure your engine to these specs, you will achieve the low enb and peak torque characteristics, but probably won't make quite as much top end power due to the flow limits of your OE heads. Even with good massaging, they will not equal the flow numbers of a set of well massaged big port heads, but the FI system will offset this to some degree because the manifold architecture of the FI system will make more top end power, all other things equal, that a single four-barrel SHP manifold.

The 2x4 system on 283s actually will make more top end power that FI due to the very short runners and huge carb flow, but it won't make as much peak or low end torque.

Duke

[Duke W.]

Re: Fuelie stroker engine cam selection

Tom
Thats one bad C-1 you've got. I too have used and will continue to use Comp Cam roller tip rockers in every Corvette and Street Rod I have.I also endorse anything that Comp Cam makes.Their tech line is great.I read a few years ago that 98% of the NASCAR teams used comp Cam products and 100% of the pro Stock.Perhaps Duke bought some cheap Chinese roller tips.Comp Cam products are made in America .I have never heard of a failure.
Stephen Barrett (21558)

I didn't buy them. As I said in my previous post, my "customer" used them against my strong advise since he got them for "free", and they are the Comp Cams product. I don't know where they're made.

They are junk. Totally useless - other that reducing valve train limiting speed several hundred revs because they're so heavy. But it shows you the power of advertising. I've known guys who will spend $150 on this sh...t, but not spend $250 on a bulletproof set of connecting rods. Go figure!

As for the rest of Comp Cams products, they are one manufacturer that I definitely don't recommend unless there are no other available sources, which is rarely the case. Check the Web for failures of their XE series. They don't Parkerized their cams. Given the overaggresive dynamics that require gorilla springs and non-Parkerized lobes, no wonder they have such a high infant mortality rate.

As far as their "tech line" is concerned... never mind, but I'm sure most can guess my opinion.

Note that roller tip rockers are a completely different animal than roller trunnion rockers.

Modern Corvette engines use roller trunnion rockers, but the tips are plain, not roller. Get the message?

Duke

[John D.]

Re: Fuelie stroker engine cam selection

Keith, Duke is really into the cams and I am just a novice at them.
To repeat some of what he said about the E900P cam here is what I know.
Elgin Industries, Elgin Pro-Stock E900 P is a match for the original Duntov 3736097 cam. Elgin is a very old cam company and reportedly makes a lot of the blanks for other cam companies.
It's readily available and is rather inexpensive. But this is a new cam for me to recommend as for 25-30 years we pushed the TRW-TP113 which become Sealed Power/Speed Pro CS113R which became Federal Mogul/Speed Pro CS113R which became history/discontinued or so I thought. Unconfimed (and I don't believe this)-unconfirmed rumor has it that the "new" Crane Cam company makes the Speed Pro CS113 R cam now.
Now just recently a customer used Dukes cam and was pleased with the performance. But he used it in his 65 FI.
Frank Sciabica was my pal & my mentor in the old days.
God forbid you did anything out of the norm to your FI engine. If you did you need not bother calling Frank any more if your FI unit had issues.


Keith, The old FI's sure do like vacuum. Take away the proper vacuum and you would be better off running a carb. Meanwhile if your FI restorer sold you a unit that was supposed to be for an 097 cam and you run another cam you can expect problems.

Nice engine Tom Parsons. I love looking at your FI unit. Talk about a mixture of Fi parts. Shows you know what you are doing as you have parts on that thing from 57 to 65. Nice job. Good nite, JD

[Keith R.]

Re: Fuelie stroker engine cam selection

Guess I should readdress the stroker/cam configuration with the FI restorer once again. Otherwise, per Duke it sounds like the LT-1 cam is the best match for this setup. Great thread by the way everyone. Getting quite an education on cam theory.

[Duke W.]

Re: Fuelie stroker engine cam selection

Like I said, the Duntov and LT-1 cam both pull about the same manifold vacuum at idle, so idle vacuum is not going to be a problem if your FI unit was originally equipped on an engine with the Duntov cam, and from what I have seen with a 283/250FI stroker with a different than OE cam, but with the same effective overlap and idle vacuum, there was no problem "tuning" the idle speed/mixture to work fine with the larger displacement.

Duke