1957 push rods

[Jack McClow CLC #15840]

I had my 1957 engine rebuilt about two years ago, and a light tapping noise (sometimes louder) has been persistent, on and off, ever since.  We were always hopeful it would eventually fade away, but no luck.  I now have the car back to the re-builder for another look at the cause of the noise and he called this afternoon asking if I can find out for him the correct, exact length for the push rods.  The service manual does not seem to have the answer.  I remember from the initial rebuild two years ago a question came up as to whether it was an early or late production engine.  We determined it had been put together sometime in the last month or two of 1956 as the engine number is 5762024016.  (This is not the original engine to the car, so the build date for the car did not help us determine the engine production date.)  As I remember, one of the changes mid-year had to do with the valve train components.  Any thoughts or suggestions to help with finding the answer to this question will be very much appreciated.
Thanks,
Jack.

[Glen]

Well I don’t know how much this will help, but this is what the parts book has to say: 

[Roger Zimmermann]

Jack, the VIN stamped on the engine will not help. You have to look at the rear of the engine to find that number: it is stamped above the cast rib on the rear portion of the crankcase, behind the LH block, according to  the "Catalog of American car ID numbers"
The change is explained in the Cadillac serviceman supplement from March 1957; see the attachment.
Years ago, someone did a mish-mash with lifters and push rods in a '56 engine. It was very noisy, like a cold diesel ...

[Jack McClow CLC #15840]

Glen and Roger,
Thanks so much.  I will pass this information along.  I really appreciate the information you have found and posted for me.
Jack.

[Roger Zimmermann]

You are welcome Jack!
Merry Christmas!

[Coupe]

What I have been told is you can use either the new or old style lifters and push rods as long as they as each component is new or old style. In other words the new style lifters have to paired with the shorter push rods and so on. You cannot mix new style lifters with old style push rods.

Be sure to check that the cups on the rockers are not wearing out. I bought after market rockers when I rebuilt my 57's engine and the cups wore prematurely causing noise and eventual failure of the push rods. The rockers were not hardened like the originals.

[Jack McClow CLC #15840]

Paul,
About how miles before the cups on the rockers began to wear?  I have only put about 1,500 miles on my engine since the rebuild, and the tapping noise has been there, to some degree, from the start.
Jack.

[Coupe]

I noticed a little tappet noise at about 2000 miles that I thought was a lifter not loading. Then it got very loud and I pulled the valve cover on the noisy side and found a broken push rod. The end at the rocker had snapped off. I thought is was just a faulty push rod and replaced it. Then another push rod broke so I started looking at the whole system, rockers, rocker shaft etc. When I compared the cups on the after market rockers to the originals that I had saved I found the cups were a lot deeper. 0ne was almost worn down to the oil galley coming from the rocker shaft. I cut the cup in half on that one easily with a hacksaw. I tried cutting an old one with a hacksaw and could barely scratch it. I did not have a full set of old rockers so I bought a new set from Terrill Machine and they seem to be standing up. I now have about 9000 miles on the rebuild.

[Jack McClow CLC #15840]

Thanks again, Paul, for your continuing assistance.  Where is the Terrill outfit located?  Good to know there is a source for high quality parts if they are needed.
I just talked to the re-builder earlier today.  He told me everything he checked out in the valve line assembly looked to be in great shape, so that was good news.  Since all the new parts seem to be holding up okay, his plan to solve the problem is to change out the push rods with ones that are just ever so slightly longer than the ones he used the first time.  Seems like a good idea to me.  I will let everyone know how this plan works out for us once the engine is back together and running again.
Jack.

[Coupe]

Jack

Terrill Machine is in DeLeon, TX 254-893-2610. Good to hear all the parts are OK. Good luck with the push rods.

[Jack McClow CLC #15840]

After nearly three weeks in the shop, the car is now back in my garage.  I had mentioned I would let everyone who helped out with my problem know how things worked out.  From what I can tell so far, the tapping noise is now nothing but a bad memory.  The trip home from the repair shop (about 20 miles) was whisper quiet.  The report from the mechanic was that a thorough inspection of all the internal valve line parts showed no wearing of any kind; everything is in great shape.  The only problem he found was that three or four of the push rods were slightly shorter than what was ideal, so he replaced all of them with new rods one incremental length longer and the tapping noise disappeared immediately.  So, with that repair, along with new resonators to quiet down the exhaust to Cadillac-quiet standards, I am all set now to go for the next step in the restoration process.  Thanks to everybody who offered their assistance and suggestions.
Jack.

[Roger Zimmermann]

Jack, I'm glad that your engine's problem is gone. I just find strange that some push rods were too short and that the mechanic was able to order push rods a little bit longer...

[Jack McClow CLC #15840]

Roger,
I thought the same thing.  But, according to my mechanic, push rods can be ordered in whatever length (within reason I suppose) as desired.
That custom order was apparently why the car was in his shop for as long as it was:  he had to determine the length of the rods needed, wait for them to be made, get them installed, and then have some time to test the engine at different operating temperatures over a span of several days to be sure the problem was solved once and for all.
Jack.