No compression -cam timing?

[Trashdog67]

My freshly rebuilt '67 318 has no compression in 5 of the cylinders! Only cylinders 2, 4 and 6 show compression and it isn't but 60 psi.
This engine had about 33,000 miles on it when placed in storage about 15 years ago. Recently I had the block bored first over, crank was good as is, and the heads were treated to hardened seats, new valves and springs. When I assembled it I was careful to install the cam drive properly. At least, that's how I remember it. Human factors studies say this may be wishful thinking. With the damper timing mark on 0 degrees both pushrods of #1 cylinder can be rotated with finger pressure.
Can I get some opinions as to wether the cam timing could cause the problem or maybe pushrod length is too long.
I have had the engine running by the way. It has a definate shudder at low rpm.
Can anyone help?!

 

[Meep-Meep]

When you line up the cam dots the #1 cylinder will be on the overlap stoke not compression, so chances are you won't be able to rotate the push rods. If the cam is way out of time in relation to the crank you will have zero compression in some cylinders and while cranking it will sound funny, kind of like a miss. Go back where you were last and recheck everything. If you want to check for bent valves just remove the rockers so both valves are closed and pressure up each cylinder with air.

 

[Pistol Pete]

I'd loosen up (or remove) the rocker shafts and unload the valve train, then do your compression test. If the compression stays low, add some oil to the cylinders (one at a time) and see if it comes up then. If so, your rings may not have seated properly upon initial start up.

If the compression doesn't improve with the oil, run compressed air into an offending cylinder(s) and listen for air escaping through the carb or exhaust, which would indicate your valves are not fully seated.

 

[Hemi Rebel]

I'd loosen up (or remove) the rocker shafts and unload the valve train, then do your compression test. If the compression stays low, add some oil to the cylinders (one at a time) and see if it comes up then. If so, your rings may not have seated properly upon initial start up.

If the compression doesn't improve with the oil, run compressed air into an offending cylinder(s) and listen for air escaping through the carb or exhaust, which would indicate your valves are not fully seated.

That isn't going to work. In order to get good compression test readings, you have to have something to compress. If the intake valve does not open and allow air in, then there is nothing to pressurize.
Once you know what cylinders are low, then loosen the rocker arms and do a leakdown test on those cylinders. If there is no leakage, i would suspect cam timing. If there is a lot of leaking, it either going to be from intake valve, exhaust valve, rings or headgasket.

 

[dryheat]

A "running" engine with 5 cylinders at 0 and 3 at 60 psi? Yikes!

What cam / cam gear did you install?

 

[Trashdog67]

Meep,
I'm using the dampener and ign timing marks. I haven't cracked open the timing cover yet.
5wndwcpe,
I backed off the rocker arm mount enough to loosen the valve pressure but not enough to let the pushrods come out of socket. I now can detect >140# of compression in the dead cylinders. (Valves are opening a little) Wow, what a difference.
I thought that there was only 1 length of pushrod available for the small block.
Things replaced at o/h: Cam (verified correct p/n stock cam), lifters, valves, springs, retainers and valve seats. NOT replaced: pushrods and rocker assemblies.
Thanks for the input from everyone.

 

[Trashdog67]

I've installed shorter pushrods and the engine runs like a clock now. Excellent compression in all cylinders.
Thanks for the help everyone. :hello2:

 

[67 coronet]

I've installed shorter pushrods and the engine runs like a clock now. Excellent compression in all cylinders.
Thanks for the help everyone. :hello2:

love to hear when a big problem gets solved by people here.