I could sure use some direction on diagnosing the rocker noise on my 392 in my 57 coronet. A little history on this engine. It was rebuilt and installed in 2018 and used for about 23,000 miles with no problems. Wife and I were driving it last year and it lost a freeze plug in the block overheated and blew a head gasket. I wasn't sure if any other damage was done so I pulled the engine to bare block and checked for cracks. Everything checked good. Reassembled with new rings and new hydraulic lifters because my grandson rolled the engine upside down on the engine stand and the lifters fell out. Engine ran fine but had noisy rockers from the first day. Drove it like that for a while and pulled the covers to check the lifter preload and was surprised to not find any that any had changed.. I readjusted all of them anyway the same amount I did when I first rebuilt the engine and it made no difference. I put about 4000 miles on it after that and got tired of the noise pulled the covers yesterday and tried different preloads on the lifters and ran the engine with the covers off but nothing changes. I pulled the manifold and valley cover and rockers enough to remove some lifters and everything looks fine. Rockers look great. Can it be the lifters? that is the only thing different from when it was first rebuilt. I purchased these lifters from Hot Heads as well as the first set. Have not run into a problem like this before but anymore I question the lack of quality on parts these days. Don't know what to do other than replace the lifters again and hope for the best. Thanks. Ed
If you ran it with covers off how was the Oil delivery to the top? Did you compare the new Lifters to the Old when you changed them? Specifically, the oil groove location on the lifter housing.
Wonder if you received the correct lifters. Compare one of the new lifters with one of previous lifters to see if the oil holes are drilled the same.
The oil delivery looks good. wish I had the old lifters to compare but I dont. Both times I purchased the lifters from Hot Heads Racing because old hemi engines are their specialty. You would think they are the same but anything can happen.
I have learned that Blind Faith will lead you down the wrong path. Do your own homework when changing parts. Just because they may fit in the space don't mean they will do the job correctly. My current lesson is Hemi directly, a machine shop that just does machine work and a home builder that trusted both him and Hot Heads parts to be correct. When everything bolts back together, you're Good, Right? "Mega Wrong!" Lucky for me the builder didn't try to fire it and a persistent Oil Leak. What I found inside while after the oil leak led to further inspection and knowing what I do, well let's just say my Wallet isn't going to be as healthy after My Machinist gets done making things Right. I made a Good Faith purchase and didn't get what I paid for, now I'm paying for it.
That's a good question. It sure sounds like a rocker or rockers and is much more noticeable when the engine is cold and when it is under load. Doesn't sound like an exhaust leak. I was surprised when I had the engine running with the valve covers off and pushed down on the rockers with a wooden hammer handle, it didn't seem to make any difference. The sound sure seems to be in the rocker area. I don't know what else it could be. It has been like this for several thousand miles and hasn't changed. Hate to put it back together with new lifters and have the same problem. I did check this morning that the oil slot in the lifter lines up with the oil supply hole in the lifter bore. That appears to be ok.
Depending on where you went with your adjustments I'd do another half to 3/4 turns in on all and see what happens to the sound.
Lifter noise should not change under load. Pushing on the pushrod end of the rockers with a hammer handle is a good test and should have increased the noise if that were the problem since it creates lash at the valve end of the rocker. I'd sure want to keep looking at exhaust if it were mine. Have you tried pulling one plug wire at a time while idling to see if the noise changes? That may isolate the cylinder involved.
Somewhere I have the Hyd adjustment info written down. I can't put my hands on it now. Must be in the Shop. Seems like it was 12 flats or 3 full rotations of the rod from Zero lash. I found a handwritten note with some cam spec's that says 1 full turn but I'm not sure what motor it's related to.
When i first built the engine, I preloaded the liters at 2 turns which comes out to about . .060 and all was well. repeated the same preload this time and no luck. also tried a bit more preload with no change. I might have to start looking for problems somewhere else because I just don't see anything wrong with the lifters or rockers. I have quite a few miles on the engine since it was rebuilt again and don't see any evidence of an exhaust leak. My headers have 1/2" thick flanges but anything is possible.
Here's what I do to find Exhaust leaks. I use a piece of rubber hose. It can be anything from fuel line to heater hose. I like about 3 feet of it. In fact I have a piece of 1/2 in hose dedicated to this job. Start the motor and hold one end very close to my working ear. I then start moving the open end all around the manifold or header and pointing it right at things where they mount or connect. The hose acts as a stethoscope and transmits the noise to your ear. To test it and see how it works go to the open end of your exhaust pipe and stick the open end right at it. Now go hunting. Exhaust leaks don't always leave a carbon mark that you can visibly see but you'll be able to hear one with the hose.
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