Cam swap help needed
07-03-2010, 01:33 AM
#1
Cam swap help needed Me and a buddy started swapping TSP's 233/239 .595 .605 on a 112 in to my 04 GTO with stock heads. We are using 7.4 pushrods also. Every thing was going fine until we bolted the rockers back on and tried to turn the engine over again. Now when rotating the crank pulley it feels as if we are hitting a stop either way we turn. We lined up the dots on the cam and crank gears. I was told that this cam should fit no problem on a stock headed ls1. Does any one have any ideas? I was really excited about getting this finished this evening but that does not look to be the case. All help is appreciated.
07-03-2010, 09:34 AM
#5
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Its a good thing you stopped when you thought something was potentially wrong. I say try it again bc yes its gonna be hard to turn the engine over while building compression. If you want to verify that nothing is hitting, simply do this: pull the spark plugs out of the engine, and then it will be super easy to roll over by hand. If something is hitting, you will feel it for sure.
07-03-2010, 10:56 AM
#7
I am a retard. It was late and I had a beer or two and totally forgot to put the rocker pedestial under the rockers before bolting them down. Thank yall for your input. We should be starteding it here in less than an hour. I will keep yall updated!
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07-03-2010, 11:57 AM
#9
It's possible. I once installed a 232/236 XE-R off the shelf plain ole Comp cam, and the damn thing took a 7.325 pushrod. I have no idea why, but with a 7.4 it was bottoming out the lifter before I got to 1/2 TQ.
NEVER assume anything when building an engine. Frankly, this whole "7.4 length should be fine" BS needs to go away period. Almost every cam I've installed in the past 3 years on a stock head required a slightly longer pushrod due to the smaller base circle on the cam.
Pushrods should be the very last thing ordered when building an engine. They should not be ordered with the cam.
NEVER assume anything when building an engine. Frankly, this whole "7.4 length should be fine" BS needs to go away period. Almost every cam I've installed in the past 3 years on a stock head required a slightly longer pushrod due to the smaller base circle on the cam.
Pushrods should be the very last thing ordered when building an engine. They should not be ordered with the cam.
07-03-2010, 12:50 PM
#10
Well we just started it up and I am completely confused. Besides the completely obnoxious valve train noise, I cant even tell there is a differant cam in there. It idles at 800rpms by it self and doesnt have anymore lope to it then my stock cam did. I did look at the end of the cam when I got it and there were the correct specs ground into it. I let the car idle up to operating temp and shut it down. I will go back out and start it again in a minute. How long does it take to quite down the drive train? I went with prc .650's btw.
07-03-2010, 01:59 PM
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Depending on the idle speed, cam lope can completely go away. The lower it idles, the more lope. Just to make sure are they new lifters or reused lifters? Im assuming they are untouched but want to verify. Also, what did the oil pressure gauge read in the car?
07-03-2010, 05:41 PM
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It sounds like your pushrods are to short and your preload is to little.
If not sure, you need to measure for correct pushrod length.
With stock non-milled heads... 9 out of 10 aftermarket cams use 7.425 pushrods to obtain correct preload.
.
It sounds like your pushrods are to short and your preload is to little.
If not sure, you need to measure for correct pushrod length.
With stock non-milled heads... 9 out of 10 aftermarket cams use 7.425 pushrods to obtain correct preload.
.