What is the best way to check for bent pushrods? I think I found my low horsepower output on my XE230/236 - Ported LT1 heads car. It seems, by the look of the eye, some of my pushrods are bent, but I want to make sure. There are also scuff marks on the piston tops, I need to look at the under better light but there is a half moon scuff mark on the exhaust side of some pistons. I can tell because the rest of the piston is covered with carbon except there. I think my valves smacked a little.

Also, i think I found my problem with non firing piston #2, there seems to carbon stains around the cooling pockets around the chamber.

 

The best way without any special tools is to roll it accross a flat surface, it will be evident if it is bent.

Small scuffs from the valves shouldnt hurt the piston, before reassembly if you cant find any cracks, just feather the scuff with some fine sand paper.

If they are still in the motor tape off the surrounding area and cover the rest of the engine and then smooth out the scuff. The only concern I have with small valve taps is a place for carbon to gather.

 

You might want to check the piston to valve clearance & your spring seat pressures. ...Im having the same problem except that Im running the 236/242 on a 110lsa and on all of my exhuast valves smacked the pistons.
Im thinking the springs I used weren't enough and caused valve float.

I bent like 6 pushrods also...if you roll them across a flat surface...look at both ends of the push rod...if the ends lift at all then they are bent. Keep us updated.

-B

 

What valve springs are you guys using?

 

I originally purchased 987-17 Comp Camp Spring, but it was replaced with another taller Comp Cam double spring by my engine builder. I do not know which. He said he could not get the alingnment right, probably because he pushed the intake valves deeper because of its 2.02 size on a LT1 head. I know he used the same rods I bought, CC Chromoly with the same 7.20 stock length. If I remember correct he had around 340lbs of pressure as tested.

 

I'm using the K-motion, K-800s with the GM 847,(234/242 w 112 lobe sep) the exhaust has .595 lift and I am not hitting the piston (cam installed straight up).

 

I was running the combination motorsports EX-612s. However I believe that I did not set up the springs correctly.

-B

 

Also how do we remedy the scuff marks on the piston tops? Do I just leave them alone?

-B