Author Topic: Back to my smoking issue >:(  (Read 770 times)

Offline JAG56Cad

Back to my smoking issue >:(
« on: July 22, 2018, 10:44:09 AM »
Well had a chance to take the left back pistons out yesterday and today and I believe I may have found my issue with the foul plugs and smoke out from the tail pipes. http://midcenturycadillacs.com/index.php?topic=3938.msg23296#msg23296

I had a feeling my problem lie with the piston(s) somehow, my last compression test reading was about 150 on all except for #6 having about 130.   ???

I removed #5 yesterday and was not happy with what I saw, both compression rings 1 and 2 were clocked about 30 degrees and the top and bottom oil ring were also about the same about 90 degrees from the compression one. The attach picture is #3 which I removed today #1 and #7 had similar ring layout.   :o

Second I removed both compression rings and found the ring gap was above the normal range of 0.013” - 0.023” both were on the range of 0.027”-0.028”.    >:(  The cylinders and pistons are bore 0.020 over (that is what is stamped on the pistons) so I have a new set coming by end of the week.

Now I’m not an expert but I would take a while guess the rings would need to be properly clock on the pistons and from my research the top and bottom compression should be at least 180 degrees from each other. The oil ring would also need to properly place and gap set at least with all gap away from the piston pin. 

Oh well as Johnny says “this is just a hobby..!”, but not a fun one when temps around here are in the 100 plus.   :'(
Jose Gomez
CLC Member #23082

Offline novetti

Re: Back to my smoking issue >:(
« Reply #1 on: July 22, 2018, 07:35:03 PM »
Piston skirt looks pretty good from here. Are these new pistons?

How is your valve guides / Valve stem clearance? Smoking could be from excess oil coming from there.

Offline Roger Zimmermann

Re: Back to my smoking issue >:(
« Reply #2 on: July 23, 2018, 02:09:41 AM »
On my '56 de Ville, I had heavy smoke from time to time after I overhauled the engine. I also removed all pistons to see if something was broken, nothing bad, and still smoke after reassembly. Finally, it was the valve for the vacuum line at the vacuum pump inside the engine which was not good. Did you check yours?

Offline JAG56Cad

Re: Back to my smoking issue >:(
« Reply #3 on: July 23, 2018, 08:41:03 AM »
@novetti

The pistons are relative new they may have about 100 hrs of run time on them since I got the engine rebuilt back in 2008. Had not got the car on the road as I was doing other restoration inside, paint, etc. after the engine was done.

The current heads are the spare ones I got way back since my original ones were both cracked, standard for early ’56. These ones were just clean and the bottom milled at the shop but the shop closed down so I grinded by hand before reassembly with same valves and springs.

I do intent to take them to a shop and have them go over and verify everything beforehand.   ;)

The issue of smoking was also present when I had the 390 (’60 if I remember) fully rebuilt and installed. I did not have the correct rocker shaft for the 390 (used the same ’56 rockers set) when I first tested the engine, so took them off and replace them with the spare 365 set. I do have a 390 rocker sets now that I could place with the 390 heads as well as the lifters and push rods as an alternative.

@Roger

Thanks, that was my first thought although the valve is/was fine I did blocked the line going up to the firewall vacuum manifold, just in case.


I still need to get the right side head off to get the pistons out on that side. Maybe taking one bolt at a time with our expected weather again in the high 100.  :(
Jose Gomez
CLC Member #23082

Online PHIL WHYTE CLC 14192

Re: Back to my smoking issue >:(
« Reply #4 on: July 23, 2018, 03:55:00 PM »
I was going to say the same - the pistons look great! Valve stem seals, the vacuum valve etc are the usual culprits. Measure the bores just to check before putting it all back together. I had a friend who rebuilt the engine in his Triumph motorcycle, but only did the rings because the pistons looked great only to find that the pistons were standard and it had been bored out +20!. Phil

Offline JAG56Cad

Re: Back to my smoking issue >:(
« Reply #5 on: July 23, 2018, 06:05:03 PM »
I was going to say the same - the pistons look great! Valve stem seals, the vacuum valve etc are the usual culprits. Measure the bores just to check before putting it all back together. I had a friend who rebuilt the engine in his Triumph motorcycle, but only did the rings because the pistons looked great only to find that the pistons were standard and it had been bored out +20!. Phil

I have the rubber cups seals that mount in the valve guide instead of the “O” rings that came with the gasket kit, did not want to take a chance.  ;)

Thanks for the 411..!
Jose Gomez
CLC Member #23082

Offline walt c

Re: Back to my smoking issue >:(
« Reply #6 on: July 27, 2018, 03:26:07 PM »
jose,
  After I rebuilt my 1955 331 it took forever to "breakin". I "used" quite a bit of oil for many miles. I also had smoke out of my downdraft tube and EVEN noisy rockers! (clicking constantly,sounded like solid lifters) A friend suggested I add some Lucas oil additive. I did and my oil consumption went from a quart every 500 miles to less then a quart after 1200 miles! Then my rocker became quiet and all is well. (50K miles since overhaul) A point of mention is that my oil pump pickup tube to oil pump did not have a gasket. (felt) Thanks to Roger Zimmerman I installed one and life is good.....feel like drinking a glass of wine like Johnny does. (by the way, sure was fun out last night in it feeling the factory air and my wife at my side)....walt...tulsa,ok

Offline JAG56Cad

Re: Back to my smoking issue >:(
« Reply #7 on: July 27, 2018, 05:05:03 PM »
@Walt,

Thanks for the 411..!

I just got back from the garage had to take a quick shower as I was totally drench, TX weather.   :(

I removed the right side head over the week and tackle the pistons today, same scenario as the left side they all had the compression rings facing down and both gaps about 20-30 degrees apart and were really gunky.  :o

I got a new set of rings yesterday and after a quick check by overlay them (old and new) it was obvious the machine shop cut (gapped) them way above the max tolerance.

I know they would need to be grind to the correct size, so that would be a project for tomorrow. Not sure how many will I be able to get done, but I’ll take my sweet time for sure. Now as for the Johnny special relaxation elixir (aka wine) that would be after the task at hand, just need for Johnny to share his secret brand.  ;D

More updates forthcoming as I progress.   ;)
Jose Gomez
CLC Member #23082

Online PHIL WHYTE CLC 14192

Re: Back to my smoking issue >:(
« Reply #8 on: July 28, 2018, 02:22:54 AM »
@walt c sounds like that was a great night out my friend. My car is non a.c. and we have had the hottest summer here for 42 years! Phil

Offline walt c

Re: Back to my smoking issue >:(
« Reply #9 on: July 28, 2018, 02:51:43 PM »
jose,
  Your comment "I got a new set of rings yesterday and after a quick check by overlay them (old and new) it was obvious the machine shop cut (gapped) them way above the max tolerance.

I know they would need to be grind to the correct size, so that would be a project for tomorrow"......well, I used to spent 8hrs on a ring set for perfect fit! Racing motors, but I fit my Cadillac 331 rings perfectly also....walt...tulsa,ok