Where to buy cam, lifters, springs?

[Joe R.]

I'm in the process of rebuilding a L-72 (427 / 425) solid lifter engine. The short block is done and the heads are done (ported and valve train installed). After reading the archives a bit, I have decided to remove the Comp Cams camshaft due to the Parkerizing issue. I will go with Federal-Mogul or Crane. I believe the lifters should come from the same company as the cam. Is that true for the springs as well? The springs are also Comp Cams at this time. The only mod is that the valves are 0.100 " longer than stock to gain me some extra lift. Should I replace the springs and valves? If so, why? Also, I saw on the board that the GM lifters part number 5232695 are obsolete. Does that mean I should get everything from Crane? On the rocker arms, I see some difference of opinion between Joe L. and Duke. Last I saw, Joe recommended roller rocker arms while Duke suggests OE. I'm mainly interested in low to mid RPM power, not so much in max HP at max RPM. But I would like to get as much power out of the engine as possible while maintaining a stock appearance to the maximum extent. So I am leaning toward the full roller rocker arms.

Joe

[Jim L.]

Re: Where to buy cam, lifters, springs?

The only mod is that the valves are 0.100 " longer than stock to gain me some extra lift.

The length of the valve stems has nothing to do with the lift at the valve. However, the extra valve stem length will affect the lengths of the push rods you need to employ for the sake of maintaining proper valve train geometry.

Jim

[Joe R.]

Re: Where to buy cam, lifters, springs?

Jim,

Thanks for your reply. I am planning to use a pushrod length checker to determine the proper pushrod length.

Joe

[Duke W.]

Re: Where to buy cam, lifters, springs?

You can buy either the Crane clone or F-M (CS-165R) cam, which you can buy through NAPA or any auto parts outlet that carries F-M brands. Buy the lifters with the cam, and they are likely from the same source. If the current new lifters are mechanical and the engine was never fired you can use them with the new cam.

Longer valve stems have no effect on lift. They only affect rocker arm geometry, which may have a very slight effect on lift, however, they may cause problems.

Buy the second design ('70-up) dual spring/retainer/damper assembly. AFAIK the only source is GM, and the part number has been posted many times.

For your application the OE rocker arms are perfectly adequate. Inspect all part wear surfaces for galling or obvious wear. If none is noted they should be okay to reuse, and it's best if the pushrod/rocker pairs are the same as how they were removed.

If the heads have been properly massaged, then there's nothing else needed to maximize top end power. Target a true CR of 10.25:1. Assuming you used OE replacement pistons and deck height is near nominal, this can be achieved with head gasket selection. Of course, you should measure deck clearance, head chamber volume, and follow previously recommended procedures to bring the CR into the target range and minimize variation.

Bottom line as I always recommend is to only use OE equivalent replacement parts, and virtually all name brand replacement parts from Federal Mogul and Dana Corp. are available from any convenient auto parts source, and both the mfgs. and outlets have online catalogs. Don't use hot rod parts for anything! The only real Improvement you need for an L-72 is the later design valve spring and head massaging is optional if you want maximum power available from this configuration.

Duke

[Joe R.]

Re: Where to buy cam, lifters, springs?

If the heads have been properly massaged, then there's nothing else needed to maximize top end power. Target a true CR of 10.25:1. Assuming you used OE replacement pistons and deck height is near nominal, this can be achieved with head gasket selection. Of course, you should measure deck clearance, head chamber volume, and follow previously recommended procedures to bring the CR into the target range and minimize variation.

The only real Improvement you need for an L-72 is the later design valve spring and head massaging is optional if you want maximum power available from this configuration.

Duke

Duke,

It sounds like I should go back to the original valves. Does anyone have the part numbers handy?

The heads that were on the engine when I first got the car are from a 67 (391 heads). They have the valvetrain installed on them. I was planning to sell them that way, but I suppose I could sell them bare and reuse the rocker arms. What is the GM part number for the rocker arms?

I can't really reuse the pushrods. Or at least not all of them. One of them shattered. How about the pushrod part numbers? I don't know where each pushrod / rocker arm came from. How critical is that?

How do I know if the heads have been properly massaged?

I plan to follow your recommendations to manage the CR. I will use the later design valve springs. I have that part number.

Joe

[Duke W.]

Re: Where to buy cam, lifters, springs?

I don't have the GM numbers handy, but likely the very same Federal Mogul parts are on the NAPA online catalog or are available from virtually any auto parts source. You don't need to buy parts from GM. They sell what everyone else sells.

If Joe or someone else has the OE or current replacement part numbers, you can cross reference them on the NAPA web site.

One exception might be the second design valve springs. So far neither I nor anyone else has been able to come up with a different source than GMPD, but I bet there is.

I don't know why longer valve stems are installed, or whether they may have any issues.

With the exception of using the later valve springs in place of the failure prone early design, there is absolutely no need to use anything but OE equivalent parts in the vavletrain.

If it works dont' "fix" it! Why these "engine builders" want to use non-OE parts is a mystery to me, but I don't think most of them actually know what they are doing or have any engineering understanding of engine internals.

Head massaging should always be checked via flow testing. In fact, since the database of early closed chamber big block head flow data is limited, I would like to see some OE BB heads flow tested prior to massaging and then again after the work is done, to verify improvements.

Right now I have a pretty good database of SB head flow numbers and know what to expect with proper massaging.

Duke

[Joe L.]

Re: Where to buy cam, lifters, springs?

Duke,

It sounds like I should go back to the original valves. Does anyone have the part numbers handy?

The heads that were on the engine when I first got the car are from a 67 (391 heads). They have the valvetrain installed on them. I was planning to sell them that way, but I suppose I could sell them bare and reuse the rocker arms. What is the GM part number for the rocker arms?

I can't really reuse the pushrods. Or at least not all of them. One of them shattered. How about the pushrod part numbers? I don't know where each pushrod / rocker arm came from. How critical is that?

How do I know if the heads have been properly massaged?

I plan to follow your recommendations to manage the CR. I will use the later design valve springs. I have that part number.

Joe

Joe-----


Valve springs---GM #3970627 or a SET of these under GM #12371061

Rocker arms---GM #3959182 or a SET of these under GM #12368082. You can also use GM #10112680 which are a direct replacement for your originals. However, these are a lot more expensive, are not as good as the 3959182, and are not available as a set.

Pushrods----originals and replacements discontinued. You can use these, though:

intake----GM #10134307

exhaust----GM #10134308

Valves----

intake----GM #3864808---discontinued; use number for cross-reference

exhaust---GM #3860002---discontinued; use number for cross-reference

[Joe R.]

Re: Where to buy cam, lifters, springs?

Duke and Joe,

Thanks for your help! I had the heads ported by Stiegemeier Engine Air Flow. I don't know if he did flow testing before and after, but I will find out. If not, I will probably get it done. Any ballpark guess at what that might cost?

Joe

[Mark F.]

Re: Where to buy cam, lifters, springs?

Hi Joe,

This is probably common knowledge, but when you have your cam installed, make certain that the lift and duration are checked before the motor is buttoned up and put back into the car.

I had a master mechanic rebuild my 327 fi motor. We ordered a 30/30 Speed Pro cam from Summit Racing. The cam arrived in the correctly marked box, had the correct cam card in the box and the end of the cam was hard-stamped with the correct part number. When my mechanic checked the cam, it had lift and duration for a hydraulic cam. Sent it back and ordered a second...same deal. Third time was a charm.

I wonder how many motors get new cam shafts installed without checking the cam specs. Granted this is probably a rare situation, but if you don't check and you happen to be unlucky with the cam, you will struggle to figure out why your motor just won't run right.

Cheers,

[Joe R.]

Re: Where to buy cam, lifters, springs?

I read a post from Joe Lucia a while back where he said that the Corvette drivetrain could withstand 500 HP and 500 ft-lb maximum. My goal is to get as close to that as possible while maintaining a stock appearance. The L-72 was good for 450 HP and 460 ft-lb from the factory. Can head massaging alone get me to my goal? I'm considering roller rockers and MSD ignition but am wondering if I can save my money.

Joe

[Jim L.]

Re: Where to buy cam, lifters, springs?

......the Corvette drivetrain could withstand 500 HP and 500 ft-lb maximum. My goal is to get as close to that as possible while maintaining a stock appearance.

Hmmmmmm.......

Sort of like, "How much horsepower can I have and still get into Heaven?"



Jim

[Duke W.]

Re: Where to buy cam, lifters, springs?

I read a post from Joe Lucia a while back where he said that the Corvette drivetrain could withstand 500 HP and 500 ft-lb maximum. My goal is to get as close to that as possible while maintaining a stock appearance. The L-72 was good for 450 HP and 460 ft-lb from the factory. Can head massaging alone get me to my goal? I'm considering roller rockers and MSD ignition but am wondering if I can save my money.

Joe

Those are gross not net as installed torque and power. The 2.5" exhaust system is "low restriction" - about 3 psi on a massaged SHP SB, but the additional flow of a 427 increases backpressure to 5-6 psi, which is a significant power loser. Backpressure increases with the SQUARE of exhaust volume flow. A 427 really needs 3" pipes. Look at the Z07/LS7.

What counts is net installed power - actually RWHP.

Forget those numbers. They're BS!

Peak torque is basically a function of displacement and CR, but where it occurs is a function of head flow and valve timing. Peak power is all about head flow!

Do your homework. Hire competent people who FOLLOW YOUR INSTRUCTIONS, and when complete get the car tested on a chassis dyno with at least two pulls within 2 percent from 1500 RPM to 6500.

If it makes 80 percent peak torque at 2000 and is pushiing toward 350 SAE corrected RWHP at the top end the job was done right, and this is possible with all OE parts and well massaged heads. Non-OE hot rod parts are a waste of money. Spend it on head massaging/flow testing.

Duke

[Gene M.]

Re: Where to buy cam, lifters, springs?

........... and this is possible with all OE parts and well massaged heads. Non-OE hot rod parts are a waste of money. Spend it on head massaging/flow testing.

Duke[/QUOTE]

I'm sure to complement head flow massage a set of one piece Manley ss swirl polished and undercut intake & exhaust valves would out perform that old technology GM stuff. Valve train stability would be better with larger diameter Crane hardened push rods and corresponding guide plates. While a double roller timing chain reduces slack and chain slop. All of these are so called hot rod parts........ In most cases these "hot rod" after market parts are cheaper than GM replacements and function better.

[Duke W.]

Re: Where to buy cam, lifters, springs?

I've never seen any comparison data between OE replacement and aftermarket "trick" valves, but based on my knowledge of fluid mechanics, I don't think they would make much difference on a road engine - all out racing engines are another matter.

I have also never seen any evidence that a "roller chain" is any more durable or accurate than the OE link-type chain.

I don't recommend buying OE replacement parts from GM. They sell the same Federal-Mogul and Dana Corporation manufactured parts as NAPA and other auto parts outlets, but GM prices, even with a trade discount are probably higher.

GM doesn't make any of these parts. They are all purchased from outside suppliers, but conform to the original GM drawings/specs, and these same outside suppliers market the same parts through aftermarket marketing channels under their own brand names like Sealed Power.

Of course, big block parts always seem to be a lot more expensive than SB parts, whatever the source.

Duke

[Michael H.]

Re: Where to buy cam, lifters, springs?

I've never seen any comparison data between OE replacement and aftermarket "trick" valves, but based on my knowledge of fluid mechanics, I don't think they would make much difference on a road engine - all out racing engines are another matter.

I have also never seen any evidence that a "roller chain" is any more durable or accurate than the OE link-type chain.

I don't recommend buying OE replacement parts from GM. They sell the same Federal-Mogul and Dana Corporation manufactured parts as NAPA and other auto parts outlets, but GM prices, even with a trade discount are probably higher.

GM doesn't make any of these parts. They are all purchased from outside suppliers, but conform to the original GM drawings/specs, and these same outside suppliers market the same parts through aftermarket marketing channels under their own brand names like Sealed Power.

Of course, big block parts always seem to be a lot more expensive than SB parts, whatever the source.

Duke

I agree with all of the above. GM valves for mechanical lifter engines are machined in two directions at the same time (swirl polished) just like the aftermarket racing valves. That machining has almost nothing at all to do with air flow or performance.