58 Cad - No compression

[Dr.Feelgood]

The heads were not touched. The only thing new in the motor are rings and lifters.

[Dickey]

Ok I stand corrected. Once a year I get to screw up I just didn't want to do it this early in the year.

I've never felt the need to limit myself to once a year to be honest.



Dr, if you've only changed out the rings and lifters then almost certainly the lifters are wrong and are holding the pushrods up too high. You can adjust this by shimming the entire rocker assembly up from the head to get by, but that will also decrease the amount of lift you can get out of the valves and should not be considered a solution.

If the lifters are holding the valves open because of static spring tension in the lifter, there is still a chance that the valve springs are just flat worn out and cannot override that last few thousandths. They were never stout to begin with and on my 390 I could push them down a bit by hand. I find this scenario unlikely given the mechanical leverages involved, but it can be tested by shimming the valve springs from the head to see if they then can override the aforementioned static tension on the lifters.


Most likely, what is happening is that the lifters are bottoming out because they are not the right part. The only way to legitimately solve this problem is to replace them with the correct parts. What prompted the decision to replace the lifters and and rings in the first place? Usually if the lifters are replaced a new cam shaft is installed so that the lobes aren't wrecked in short order.

[Dr.Feelgood]

The lifters had slight wear on the bottoms So I figured I'd spring a few extra bux and get new ones since the motor is already open.

When taking the pistons out of the cylinder, the rings of a few of them were jammed into the piston head with carbon build up. Trying to break them free resulted in breaking the rings into several pieces. So new rings were in order.

I am flipping through receipts to find the part # of the lifters I bought from Autozone. Them maybe run a check to see if anyone else has had a problem.

[Dr.Feelgood]

Thank you all for all the help so far!

[travlinman]

You have to watch what You buy and where You buy it. Back to the lifters. I found some places that sell a cheap lifter for a 472. It also says it fits BB chevys. The lifters from Caddy parts houses were more and were caddy specific. With the difference in plunger travel, I think it was .050, it would work with adjustable valves and MAYBE with a caddy with new valves. The deal is as the valve and seat wear, the valve stem moves farther up in the head, making the valve stem longer. A valve job also does this, so the top of the valves have to be trimmed. I still think Your lifters are bottomed out. It's easy to check. With the valve in closed position, You should be able to spin the pushrod with Your fingers. Also, push hard on the pushrod end of the rocker arm, there should be a little movement downward.