jtaylor16

iTrader: (3)

Had my car tuned at rpm last week and it wouldnt make power past 5500 rpm when my set up should make power up into the 6200-6300 range. the motor is an ls1 shorts block, manifold, and heads, with everything else being ls6. talked to a family friend that builds race motors and he said that for what ever reason the pushrods may be too long not allowing the lifters to pump all the way up when getting into high rpms. he suggested going back and checking all the clearances and lash and if off getting shorter rods or shimming the rockers, this theory sound right to most people? Believe me, I deffinetly trust his advice i just wanna see if anyone else has any other ideas if thats not it

badazz81z28

iTrader: (6)

Did you measure for pushrods the first time around??
Honestly, I don't think thats it.

Did you do a cam and NOT upgrade the springs? (That would be my guess)

thunderstruck507

iTrader: (18)

More likely the ls1 intake is a big part of it. It was for my car.

Could also be the valve springs if they were not set up correctly (if they are stock don't even start the car again...).

The cam could also be off if it was not degreed when you put it in.

Pushrods could also be too long or too short. What length are they? What brand cam and its specs? You may need to measure and buy the correct length pushrods.

mark21742

I'd look at valve spring and if the cam is in right like said above

jtaylor16

iTrader: (3)

the cam and springs are both 02 ls6. springs were pressure tested after being put into the heads, and the cam was timed correctly when put in. unfortunately i was not the one to put the motor together and pr length was not checked....

thunderstruck507

iTrader: (18)

If you put a ls6 cam in a ls1 engine, I think it requires ~.025 longer pushrods. That could be the problem. If I remember correctly the ls6 heads with sodium valves had different length valve stems.

It also changes things if the heads were milled or shaved any and if the headgasket is not stock type.

jtaylor16

iTrader: (3)

ill have to look into what thickness head gasket was used and if anything was ever taken off the heads, like I said I didnt build this one. but is this atleast sounding more like a pushrod issue?

thunderstruck507

iTrader: (18)

Yes, if the pushrods are stock then that is almost certainly the problem. Is the top end also really noisy?

Pull a pushrod and see what it has. If they are aftermarket they will be labeled both brand, wall thickness, and length. You are likely looking for 7.425"

If they are stock they for sure need replacing both to get the correct length and also because stock pushrods are weak and prone to bending. I have never pulled a complete set of pushrods from a ls1 (even one which was running correctly) that did not have at least 1 slightly bent pushrod.

Cosmos

iTrader: (15)

My ls1 intake made power until 6.2 or so. Then died really hard

jtaylor16

iTrader: (3)

yea the push rods are stock ls6 rods, but what if ur saying is right they are still too short

thunderstruck507

iTrader: (18)

https://ls1tech.com/forums/dynamomet...1-ls6-cam.html

These are quotes from the thread:

"copied from TR's website:

LS6 Camshaft - 204/218 .551/.541 117.5 LSA Please note that this cam has approximately a 0.050" smaller base circle than a stock LS1 camshaft. This smaller base circle will require longer pushrods for applications with stock length valves and no milling for the head surface."

"with you current 7.4 pushrods you're not achieving the full .551/541 lift ... This will give you full lift of your cam at the valve & will likely correct the missing power."

jtaylor16

iTrader: (3)

thanks for the link thunder