I have a 440 with 2355 pistons .030 down, 906 heads with 2.14 intake valves, xe274 cam. MP shim head gaskets. Cranking compression is only 125 psi. I advanced the cam 4 degrees and gained 20 psi cranking compression but my intake valves Clearance is almost nothing now (.020). Car is 68 b body wagon with 4.10s and 2500 stall. Should I swap cams to bring cranking compression up? Suggestions? Thanks!

How thick is your current head gasket?If its a .020 steel shim already a switch to closed chambered heads will help

I would for sure put it back to where it was for now (& how much clearance did you have then?). Yes I would call several cam mfrs to see what they say. "Dwayne" -68plymouth (sp) on here is the best. I'm in the same boat ex I am in the mockup stage & I might cut notches in the pistons/keeping track of the gram reduction & sub in heavier pins if it comes down to it.

How are you doing you measurement? The cam is 230 at .050 and .480 lift?

That combo and 125psi don't really add up in my mind.

First thing I'd do is borrow another compression tester and redo the test.
All plugs removed, battery charger on, carb wide open.
Test all cyls at 4 pumps and 8 pumps.

If you haven't, degree the cam so you know where it really is.
I'd shoot for 106-108.

With the info you posted, at .030 over...... Even if the heads were 90cc, it would still be almost 9.4:1.

Plugging the numbers into the Wallace calculator shows about 150psi, which is plenty for that cam....... And no quench.

If the heads were 84cc instead, the CR would be 9.85, which would add about 10psi to the gauge.

I thought I might have to cut the piston reliefs when installing the CC .650/.650 solid cam in my stock rebuilt/balanced 1968 6-pak bottom end, quite surprised when we found we had adequate VTP clearance w/039 fel pro's with the 2.14/1.81 906 heads, 1 thing that sticks in the mind from all those years ago.....only .020 with that cam, what was it straight up?

Thanks guys for all the help. Think I found my problem.... Is seat height different on a solid vs hydraulic lifter to compensate for preload? I've been using a hydraulic lifter full of washers to make it solid...

solid "cup seat height" is way lower (shorter) than a hyd lifter, not sure why tho, more than preload I would think.

why?

What I'm getting at is I took I hydraulic lifter and made it "solid". However this is pushing the valve open much more than a true solid lifter would open if the seat height is so different. I'm reading the seat height is ~.030 shorter in the actual solid? Does my logic make sense? Thanks!

the push rod seat height difference between solid and hydraulic is about .120". if your using stock rockers then the stock push rods are too long. if this is the case then I don't see how you could even get 125psi cylinder pressure but would definitely have piston to valve issues. if you want solid lifter performance then why not just use a solid cam?

I am using hydraulic lifters, stock rockers, stock pushrods. What I did was made a checking lifter out of a old hydraulic lifter. But if the pushrod seat height is that much different than my checking lifter that I made is terribly inaccurate. Sounds like I need to get an actual solid lifter to get an accurate PV clearance.

Use an actual solid lifter and an adjustable length checking pushrod, along with checking springs on the head.
Adjust to just zero lash with the cam on the base circle....... Then do your checks.

With that cam at the correct c/l......... There should be plenty of clearance, unless the heads have been milled a bunch.