Peak Cylinder Pressure

[cudabob496]

Really surprised, that I got these numbers on a 17 yr old engine!

Cylinders 1,3,5,4  190,195,190,195 Psi

[Cuda Cody]

How many miles are on the engine?  Those are great compression numbers!   

How's the rest of the cylinders (2,6,7,8)?

[cudabob496]

about 60,000 miles of weekend warrior-ing.
Only had time to get to the most accessible cylinders.
Might need another gauge setup to get the other 4.
Ya, I'm shocked. Expected 120-130, especially with
the cam duration( if that affects it). And the JE Pistons have
the thinner rings.

[RUNCHARGER]

What gas are you burning in it?

[cudabob496]

92 octane, with a little octane boost thrown it.
It was built to have a CR of 10.5:1

[RUNCHARGER]

Working in a garage in the early 70's I seen a stock 429 interceptor at around 220. I seen a 428 Thunderbird up there as well. Short duration camshafts I guess.

[Racer57]

Cam duration/overlap has a lot to do with compression numbers.

[cudabob496]

Working in a garage in the early 70's I seen a stock 429 interceptor at around 220. I seen a 428 Thunderbird up there as well. Short duration camshafts I guess.

but that's the weird thing, as my cam is 254/258 at .050.

Checked one of the cylinders this morning, when engine cold,
and it was down only from 195 when hot to 187 psi when cold.
Would have thought it would be much lower?

[chargerdon]

Actually, in my experiences,...

Cold pressure readings usually 10% higher than warm.    I think the block cast iron expands more than the aluminum pistons do from the temps...    Is your engine iron or aluminum block ?

[cudabob496]

Actually, in my experiences,...

Cold pressure readings usually 10% higher than warm.    I think the block cast iron expands more than the aluminum pistons do from the temps...    Is your engine iron or aluminum block ?

iron block, Stage VI alum heads, but forged pistons, which need to warm up to
seal better.