Worked Performer RPM heads and intake overkill for stock cam/block?

[jaymac]

Hey guys; haven't posted in awhile, but back w/ a question:
A friend of mine is selling Edelbrock Performer RPM heads w/ a "Stage 3" Cobra intake, both ported and polished. I don't yet have enough info for cfm specs or the degree of work done, but would bolting these on my stock cammed, stock block be overkill, and would I lose alot of bottom end compared to my current combo (slightly worked GT-40P's and explorer intake)?
They came off a 347 supercharged 93 cobra, FWIW....
thanks for any opinions~
J

 

[JBeezy53]

You are going to lose low end but gain a lot more top end. A cam would be a good addition and I'm sure everyone is going to tell you to get a custom, if you want to get the most out of your Heads and intake. In the end it all comes down to what your car is going to be used for mostly.

 

[seven12seven]

Thats too much cylinder head to run with a stock cam. Most of those have 2.02's in em I think. Im not sure you can just "bolt them up" they may require different rockers and pushrods etc. If you really want to do it right you should probably at the least throw a cam, rockers, pushrods, and llifters, those heads are made for 6500+ RPM

 

[X302LX90X]

Those heads could either be 1.90 or 2.02. Off of the car they were on they were probably a 2.02. For a stock bottom the 1.90 are nice because it allows piston to valve clearance for a decent cam and rockers. You might end up stuck like me. I got GT-40X with 2.02 put in them (not from me) and I can barely run a MP B cam with stock rockers. Either way your car should run much faster with those heads.

 

[87'GTstang]

You should lose some low-end torque. This is mainly going to happen because you will have much larger than stock port work on the cylinder heads and the valves not opening in a "matched" manner to what the valves are capable/trying to flow into the combustion chamber. This should create a "lazy" airflow situation. Top-end should work well though.

Bottom line: try to get a cam that matches flow characteristics of what heads are being used, it just doesn't make sense to go overkill on such a mild-mannered cam.

 

[jaymac]

I believe the heads have 1.90 valves. They guy is calling the engine builer who did the work to find out the specs. He is pretty sure they are 1.90 though.
Edelbrock does reccomend new pushrods, and the only reason i didn't do rockers witht the GT40P's is because they were shaved 0.030" and I didn't want p-to-v issues.
I also didn't cam it because it's SD, although I've seen a few AFM cams and others that will comply w/ SD.

Lastly, what do you guys think a fair price would be for these used heads, assuming there was some work done to them?
He's gonna make me an offer tomorrow - what would guys consider fair?
Thanks again!

 

[87'GTstang]

Those heads can be had for around $1050 new. With just that, and usage of say less than 20k miles, I wouldn't take it for anything higher than $800. It also depends on what kind of work he has done to them, if it is legitament work I would pay accordingly as to how wild the work is.

If they are 1.90" valves, then you aren't going to be going crazy with them, the current heads you have now are like 1.84" I think.
If you have gt40p heads "worked" a little, it depends on what you are trying to do with the car. With the current heads you have now though I wouldn't look for too much of a gain if very much at all, you still have that cam trying to flow the same amount in the combustion chamber as with the stock heads.

If it were me. i'de keep my worked gt40p's and the intake, especially if I were not straying from the stock SD-friendly cam. Although, it all depends how sweet the deal is for the edelbrocks, then i'de either shelve them for a future plan, or sell whichever set would be less valuable to me.

 

[jaymac]

Good answer;
I think some of the benefits would be the wieght savings by going to aluminum, a small increase in valve size, and the ability to go to a bigger cam now, as these heads I don't believe are milled, and the P's are. Also, the ability to change plugs w/o removing the header would be icing on the cake.
there are a few cams I know of that are SD friendly, and really, i should make the MAF swap sooner or later anyway. I guess like you said, it will depend on how sweet of a deal he offers...

 

[jaymac]

any other quotes on what a good used price would be?
(More of a "talk" question...sorry)

 

[bcd]

from what i have seen you wont gain much with the new heads and a stock cam because they dont really outflow p heads until the higher lift numbers. so to cash in on the heads your really gonna need to change the cam. just my opion though.

 

[jaymac]

the big reason I haven't changed the cam is that I had the P's milled 0.030", and am worried about p-to-v clearance maving milled the heads. If I swapped heads again, i would feel more comfortable camming it...
Wouldn't the slightly larger valves and any porting work done to them, combined w/ the weight savings, present a step up?