RednGold86Z

iTrader: (1)

I've purchased a set of used edelbrock centerbolt heads and a 2032 cam for my 5.7L GTA. I'm thinking of buying some Comp Pro-Magnum roller rockers (1.52 ratio) and need to install it all in one weekend without the option of using a pushrod length checking tool. What length pushrods are needed? I emailed edelbrock and they said that with stock stamped steel rockers, pushrods that are .1" longer are needed, but if roller rockers are used, then stock length is OK. How can this be? Do rollers have that much "offset" built in, or are they usually more geometrically tollerable of pushrod length?

Any suggestions on what brand, and part number to buy? I'm looking for reliability here too, since the car doubles as a test car for the company I work for, as well as daily driving.

Thanks in advance

OMINOUS_87

Are the heads milled, block decked, what head gasket?

All plays a part.

RB83L69

It really doesn't matter what the rationale for wanting to do this is, the answer is always going to be the same. The parts do not feel your personal sense of urgency and decide accordingly to adjust their dimensions to the optimum value to co-operate with you (unfortunately).

There's no way to be certain that you'll get the right length without measuring them. Every engine is different; even the same group of parts won't always work out to needing the same length push rod.

At a guess, I'd say that they'll probably need to be longer than stock; .050" would be a good beginning guess. That's a safe guess with any reasonable aftermarket cam. But, they might not need to be the stock length, or .050" might not be enough. It's just a guess, nothing more. Based on a certain amount of experience, but still just a guess.

What you might want to do is to order 3 sets; like stock, .050" long, and .100" long, and a push rod checking tool; and return the sets you don't use.

RednGold86Z

iTrader: (1)

Everything is stock - block. Used (200 miles) but unmilled Edelbrock heads. I'll be using the recommended head gasket I suppose. I was just hoping to find someone else who has a similar combination.

The Edelbrock tech guy said that with stamped stock rockers .1 longer is required, but with rollers, somehow stock is OK, what's up with that?

I've also heard some horror stories about actually trying to measure required pushrod length and getting it wrong (ala trickflow g1 and 2 threads on here a while ago), and was just hoping to find some better advice on where to start. Is .05 off going to be the end of the engine if it's wrong, or is it just going to likely wear the guides a tad faster, or really fast?

How exactly do pushrod length checkers work? Do you aim for a contact path in the middle, or do you have to center it at some lift point.

OMINOUS_87

Well, for starters you are adding .025 in height by running a Felpro 1003, which is the hipo gasket the Edelbrock recomends.

1003=.041
stock shim=.015

No one here will recomend to you any specific length pushrod, all they will do is recomend to you the proper way to check height at your motor to determine what you should actually buy.

You are barking up the wrong tree if you think you are gonna get a hard answer, almost every application is different.

ede

there's no way to know what you need without checking

RB83L69

http://www.compcams.com/catalog/278.html
http://www.compcams.com/catalog/279.html

RednGold86Z

iTrader: (1)

Thanks for the links.

Another question is the distributor drive gear. I checked the website and cave crane a call and they say these cams do need to use a bronze or whatever gear (no surprise, just wanted verification), so I looked in Summit and see these new polymer gears from Comp. Are they any good? Anyone using them? Summit doesn't list one for .427 shaft, which crane says is the right size for the external coil hei. I'll give em a call, just wondering though if anyone has used them or heard anything about them.

Later

RB83L69

You don't need a special gear for that cam. It is cast iron. Your regular stock one will be just fine.

Real rollers need the softer gears; typical street rollers are made of the same material as typical street flat-tappet cams, and therefore don't need to be treated the same way as steel billet cam cores.

RednGold86Z

iTrader: (1)

I thought that might be the case, but when I called crane they even checked the part number, and he said that it needed it, but then I looked at the cam, and it looks like it has a gear pressed on and located with a pin, and I wondered why would they go through the trouble to press on a gear that wasn't right for most distributors, when they could put the right gear on, and save everyone the trouble. It did surprise me actually, because I've never heard anyone mention that with these cams and our distributors, but I just wanted to sound like I expected it. It's all over the tech section on cranecams.com which is another reason I called, and that guy didn't clarify things very well, but that's the answer I got. Maybe I'll just call again and grill the guy about it.

Thanks,