I just had my 55 nailhead 322 rebuilt. the problem is in the valve train. I had hardened valve seats with stainless steel valves. the shop used the original steel type guides. (I think there is the problem) The car will run for about 20 miles then the valves will start to hang up resulting in broken rocker arms or bent push rods. Any suggestions wil be appreciated thanks Bob
I hope you get it figured out. Have you tried a golf club on your mechanics noggin :laugh: Good luck. Mark
either wrong sized guides or valves . when the valves & guides each expanded , when they got hot , everything seized . my guess is the wrong guides .
I have seen this before. Many times you can have the guides honed so the valves won't hang up. This is much easier than having new guides put in and if done by a competent shop will not give any future problems. The engins shop that does my work has had to do this a few times on some pretty big $ engines. It is frustrating but not the end of the world. I recommend that you also make sure the rocker shafts are on in the right direction-they have oil passages on one end to feed the rockers and if the rockers don't get oil... This would be fairly obvious as the rockers usually gaul on the shaft or discolor. I would just hate to see you chase something else for no reason.
did you try taking the valve covers off then starting the motor to see if anything looks wierd while its running?
Couple of possibilities on the valves/guides hanging up. If you had the stock valves reground, it's possible that some of the chrome on the stem has worn off. (that's only assuming that they did things the same way back then) Iron guides aren't very 'forgiving'....if you have stems that are worn, or a tight condition from something - they may very well tighten up, gaul the stem/guide, and hang the valve open. :eek2: New iron guides work much better with new valves. Another possibility, is that when the guides were pounded in, the end that they pounded on quite likely has tightened up a bit. Alot of guides get pounded in from the bottom side - that way, you can spot face them and get rid of that problem. Sometimes, a chamfer tool will clean up where the end of the guide tightened up. At the very least, a reamer and then a small ball hone should be used.
