1956 Cadillac 365 Rebuild Problem

[flahivek]

So while assembling my 365, I got the passenger head on and rocker assembly, torqued everything down, and then rolled the engine over to make sure it was all good. Everything was fine. Now onto the driver side head I get everything on and torqued down and i bent two push rods. I figured maybe I wasn't careful enough to get them seated in the lifter? Then I take the rocker assembly off, replace the push rods, roll engine over, and reinstall. Everything toques down fine no issues. When I go to roll to engine over, it does about 1/4 turn and stops. As if there is valve interference or something hitting it. I just had machine work done on the block and heads rebuilt. Any ideas? Do I need to take the head off and check it?

[fishnjim]

Barring a typo, it should be a 429, not 365?

[Bryan J Moran]

And should be in the Technical section.

[flahivek]

1956* 365

[dn010]

I would start by making sure your cam and crank sprockets are aligned in the proper position.

[flahivek]

I checked to make sure and the dots lined up fine. What's weird is that the passenger side head and rockers there's no problems and the engine turns over fine but as soon as I tighten down the driver side rockers there's an interference.

[dn010]

At this point, it should be pretty easy to look in the spark plug hole on the cylinder of the offending valves to see if the piston is up with the valves coming down as you're fastening the rockers.

If it is not the camshaft being out of time with the crank, other possibilities could be that you have a few bad lifters that won't collapse, wrong length push rods (probably not it-you would have noticed) or your deck/heads were milled beyond spec which would be pretty hard for a good shop to do so that is highly unlikely as well.

If you replaced the timing chain set, I'd compare it to the old sprockets and see if there are any differences with alignment. Unfortunately, the quality and accuracy of replacement parts these days are very questionable.

[Bronze]

It "should" not interfere even if the timing was out of alignment. There engines are not "interference" engines. IE even if the timing chain broke there should be no interference. However there was a change in lifters/pushrods 1957. shorter rods, higher lifters. -57 lifters work fine on 56 if the 57 rods are used. A mismatch could be disastrous. Are all the rods same length? Are all lifters same height?
I also remember someone finding out he had some aftermarket rockers with wrong dimensions. Do all rockers look the same? Did you turn the engine over without the head on? Do all pistons stop at deck level?