I recently performed a compression test on my 94z an got 170-180 psi on all cylinders. I have read on other web sites that the LT1 has a low cranking pressure because of the LSA on the camshaft(145-150psi). Does anybody have any thoughts on why the psi is so high? Could a worn timming chain cause this?

 

I only checked cyl. 3 at school for an assignment and I got 200 psi.

 

I don't think there is anything unusual about seeing 170psi on a stock LT1. Mine ran 185-190psi.

But the actual numbers aren't all that reliable. Its the DIFFERENCE between the cylinders that counts. You can get higher numbers by letting it crank a few times extra, if the engine is hot, if there is any liquid (fuel - if you didn't disable the injectors) in the cylinder, if all the plugs are out, giving a higher cranking speed, etc. You will get lower numbers with fewer cranks, more clearance from a colder engine, failing to block the throttle blades open, etc. That makes the number.... 145, 175 or 195 almost meaningless. Its the variation across the cylinders that you have to focus on.

 

Thanks for the info

 

thanks for the info

 

I did compression on all 8 of mine 2 days ago, and the were all between 155-167. That was with only 2 cranks. One one cylinder, I let it crank 3 times and it rose to 180.

Z