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1956 Cadillac engine rebuild update

Started by carguyblack, March 10, 2018, 05:11:01 PM

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carguyblack

It has been awhile since posting about this ongoing event but here's the latest. I have been experiencing poor engine running since the complete engine rebuild this fall. I had poor vacuum and lousy idle with no effect in trying to adjust the carb or anything else. I don't know how I could have gotten in front of this and maybe some of you experts out there could weigh in but the problem seems to be in the length of the push rods and the fact the apparently the valves weren't being allowed to fully close. What had occurred was when the block and heads were milled, the machine shop had to go quite far down on one side to satisfy him to get a good surface match. To give you an idea, he took it down so far that the engine serial numbers were taken off the block as a result of that. Point being, this explains why the push rods were then too long causing all the other symptoms. We ended up shimming the rocker train on the bank that had the uneven compression .015 with copper shims. I reassembled it all this morning and it certainly runs better. Adjustments to the timing and carb still need to be done to dial it in properly after all my messing with everything trying to get it to run smoothly. By the way, everything is new parts in the entire engine.
How, as the engine was being put together, would someone know that this was going to be a problem and that shimming would need to be done or shortened push rods or whatever? Should my builder have known this and tested it somehow as he was putting it all back together anticipating the issue before all this frustration?
I hope I am now on my way to a smooth engine and a good summer of driving. I wasn't able to take the car out even once last summer between the machine shop and the assembler. I missed the old gal.
Chuck Dykstra

1956 Sedan DeVille
1956 Coupe DeVille (2 sold)
1957 Oldsmobile 98 (sold)
1989 Bonneville SSE

Roger Zimmermann

When I had multiple issues, the guy helping me found a warped intake manifold. After it was corrected, a bad ignition coil was replaced. At the end, he found, when the engine was hot, that some valves were not closing. Instead of shortening the push rods, he let fabricate stainless shims in 0.5 mm and 1 mm thickness.
As the metal fabricator charged the same amount for 4 tan for 20, he did so many that I still have a bunch of them. If, during our email exchange, you would have told me about that, I would have sent some...
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

walt chomosh #23510

Chuck
  LOVE that beautiful black coupe of yours! Some shops who do a lot of motor overhauls will be far ahead of others who "claim to be experts". I built so many small block Fords at one time in my life that I figured that my 331 would be a piece of cake. Well, not so. I fought lifter clatter for quite a number of miles (and rings not breaking in!) then oil pressure problems. (not to mention my vacuum pump...low vacuum)  Your comment "everything is new parts in the entire engine" certainly involves imported parts which are ALWAYS suspect. (I like Terrell Machine parts for the good stuff) My block and heads were also trued and I even machined some off of my rocker shaft pedestals before all was good. The hydraulic lifters have an operating range and getting near the edge can lead to valves not closing completely (hot/cold motor situation) and the other edge can lead to lifter clatter.
  In my case I fought one headache after another. But now,all is well....it is good....walt...tulsa,ok


INTMD8

After milling lifter preload should be checked.

This would be done by getting a lifter on the cam base circle, tighten rocker shaft to just take up any free play in the valvetrain (zero lash but no lifter compression) setting up a dial indicator on the pushrod side of the rocker arm then torquing the rocker/rocker shaft. The amount of lifter depression is preload.

I aim for .080-.090.

Fwiw you should do this and then order the correct length pushrod.

Shimming the rockers is not technically correct as it alters the valvetrain geometry.  To remain correct you should be shortening the pushrod, not raising the pivot point of the rocker in relation to the valve tip. This brings the wear pattern from center of rocker tip and center of valve to the outside of the valve and outer portion of rocker tip.

May not ever cause you a problem with a minor amount of shims but if it was mine I would be checking preload and ordering pushrods.

Roger Zimmermann

Jim, your observation about moving the pivot point is absolutely correct. However, what are you doing when you are in the middle of nowhere and there is just one given length of pushrod?
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

Eldovert

High performance engine builders have to have custom length pushrods made ...fairly common in that world. With our old Cadillac's having the block deck cut and the heads shaved can put us in the same situation. The fix is to order a adjustable pushrod. Once the proper length is determined one can order the correct pushrods.
Cheers,Pat MacPhail

carguyblack

Thanks Walt. Yes, that Coupe was the best. And I sold it. And I got into another headache instead because life was too easy. And I wish I kept the Coupe. And I wish I hired a better mechanic. And I wish it worked right the first time. And I wish the Wizard of Oz was real.
I did buy all my parts from Terrill's. Great folks there. No problem with the parts but rather with an experienced know-it-all who wouldn't be told any of the forewarnings about the 365 engine builds that I gleaned off this forum over time. Told me not to worry so much. Now I'm left holding a big old bag of something. Trying to turn it into lemonade, I hope. Soon. I think I'm on the right track now. I'm passing on the suggestion of not changing the geometry to my new mechanic who determined the "fix" to see what he thinks about it. He's a good engine guy but only about 40. The other guy who put the engine together was raised with these cars and is about 65. Thought I could trust the old timer. Oh well. Could of should of would of!
Chuck
Chuck Dykstra

1956 Sedan DeVille
1956 Coupe DeVille (2 sold)
1957 Oldsmobile 98 (sold)
1989 Bonneville SSE

CadillacRob

I just got my 56 365 back from the machine shop.  Very nice old guys that did the work but not everything was perfect.  Mainly they forgot to give me all the parts when I picked it up.  Realized I was missing a few items which are rare and pricey to source.

All that being said, God I hope she runs happy.

As for the OP, I guess the milling of the deck or heads caused the pushrod length issue, but, since I don't think it was mentioned, 1956 Cadillac 365's were a transitional year depending on serial number.  Everything prior used a certain spec pushrod length and lifter.  After the change they used a different pushrod/lifter combo.    Mixing of the old and "new" styles would be obviously problematic.  Hopefully you've got it figured out.  Good luck !
1950 series 61 sedan
1956 coupe de ville

INTMD8

Quote from: Roger Zimmermann on March 11, 2018, 11:52:56 AM
Jim, your observation about moving the pivot point is absolutely correct. However, what are you doing when you are in the middle of nowhere and there is just one given length of pushrod?

Well I would shim it if I needed it to run in the meantime but there are a bunch of good companies that can get you any length pushrod you need. Just might take a while to get to the middle of nowhere  ;D

Roger Zimmermann

I could check that in a year or two when my scale model is finished...
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

INTMD8

If you ever end up needing something I have had good luck with this company-

https://www.pushrods.net/custom-pushrods

Roger Zimmermann

1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

John Washburn CLC 1067 Sadly deceased.

Folks,

I am sure this has been discussed but just in case.

The support shafts that the rods go thru for the rocker assemblies only go in one way. If you install them upside down the clearance will be wrong and you will suffer the problem you have described. Feltz at Terrill is well aware of this problem.

Just a thought.

John Washburn
John Washburn
CLC #1067
1937 LaSalle Coupe
1938 6519F Series Imperial Sedan
1949 62 Series 4 Door
1949 60 Special Fleetwood
1953 Coupe DeVille
1956 Coupe DeVille
1992 Eldorado Touring Coupe America Cup Series

J. Gomez

Chuck,

Johnny is 110% correct as always, believe you me I made the same mistake mechanic slight slip when I mount the rockers.

The left side both inner ones were flipped and the right side on was also flipped. When I test my compression on those cylinders they were “0”. I have an optical scope and notice the valves never closed.

After a few colorful words,  :D I had to remove the rocker arm shafts and rotate them 180 and back to normal
J. Gomez
CLC #23082

fishnjim

Precisely why I chose a reliable noted builder and made him dyno and break in the motor before I accepted it.   He had to do some shimming, etc. and ran it to 5000 rpm.   Worth the extra few hundred.   

John Washburn CLC 1067 Sadly deceased.

J. Bozin,

Not trying to start a argument, but I believe you missed the point. There is no need for shims on a 56 Cad if the rocker arm supports are installed correctly.

I have rebuilt a few of these and deck the block always. No problem with push rods either.

The Johnny

Now installing one wrong lifter is another issue.
John Washburn
CLC #1067
1937 LaSalle Coupe
1938 6519F Series Imperial Sedan
1949 62 Series 4 Door
1949 60 Special Fleetwood
1953 Coupe DeVille
1956 Coupe DeVille
1992 Eldorado Touring Coupe America Cup Series

carguyblack

I finally got the engine to run as it should. As with many issues on these old cars, it wasn't just one thing. I had a defective restored carb where the accelerator pump failed. The timing and carb adjustment (when another carb was installed) were way off, too. And, against what has been posted here, we used .040 shims under the rocker shafts. The compression was better and more uniform as we experimented on just one side first so we decided to go that route all over. My very qualified engine machinist said that this is not uncommon for him and that some engines just require that after machining. I realize the hydraulic lifters should balance this phenomenon out, but they didn't and a couple valves were not closing all the way. The block was decked enough that the engine serial numbers were milled away when this was done. I was forwarned that would happen but the machinist needed that depth for corrosion and leveling. Anyway, in the end the engine is running strong so I'm hopeful that this can be a summer of driving the thing and not just looking at a lame car in the garage with the hood up all summer again. Thanks so much to the forum for the advice and encouragement along the way. On our own, these types of experiences can be very disheartening, so I thank you all!
Chuck
Chuck Dykstra

1956 Sedan DeVille
1956 Coupe DeVille (2 sold)
1957 Oldsmobile 98 (sold)
1989 Bonneville SSE

Roger Zimmermann

Chuck, I'm glad your engine is running as it should. One question, however: if the block was decked (in my school English, I would write "milled"), are the piston not protruding the block? Or is that slight difference compensated by the head gasket?
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

carguyblack

#18
Hi Roger,
That would be a logical thought about the pistons. I don't profess to understand all the geometry of the engine but that certainly makes sense. Apparently, there is enough space there to not obstruct and the rocker shaft shimming aided the upper end situation with the push rods. I sound like I know what I'm talking about but I really don't! I just rest on my mechanic's and machinist's advice and it seems to have done the trick. Great hearing from you.
Chuck
Chuck Dykstra

1956 Sedan DeVille
1956 Coupe DeVille (2 sold)
1957 Oldsmobile 98 (sold)
1989 Bonneville SSE

Jeff Rosansky CLC #28373

Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille