VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 Smokey '36

My Chevy has always seemed too smokey out the exhaust pipe. I have a set of the little after market metal caps that go on the top of the valves and wondered if I should install them. If this is normal to give off smoke I won't worry at all about changing things. The engine was a factory new block and I have only a few thousand miles on it over years. any pointers out there?

If you did not disassemble the engine and insttalll new rings I would suspect it to be a ring problem.

Hello JFranklin,

So to get it clarified is your smoke blue, black, white, or gray like from Lucas wiring? Each one of those has its own cause and possible solution. Next question would be when does it smoke? On start up, on deceleration, acceleration, all the time? Again each one of those has its own cause and solution. Last question would be how much does it smoke? Probably somewhere between a huge mosquito killing cloud, and minor that only you and someone saving the planet in a Prius would notice.

Art

It appears to be oil burning. The engine was dissasembled for inspection and re-gasketing by a mechanic friend but the factory rings were left installed. I think it smokes more than it should. I see it at idle but no clouds being while driving. (10/40 oil) but this is the only overhead valve vintage Chevy I own. The engine is a GM factory crate replacement engine. It has always smoked.

Could it be possible that the rings have not set yet since it is a new block? I did have a Corvette 327 replacement block that seemed to take forever for the rings to seat.

Dave

Back in the 1950's for some reason we had problems with new factory short blocks using oil. They used the same non-expander piston rings that were installed in new cars. The only cure was to replace the rings.

Abig cloud of blue smoke at start-up is usually oil running down the valve stems.

This engine was dated as built in 1939 for replacement service. Would it have the rings you mentioned?

YES

Are the proper rings still available? even if I don't replace them now it would be good to obtain a set.

I would run some of that light oil in the gas to see it the rings will set first. There are several brands on the shelf at auto stores. It will smoke but after you refill the tank it should clear up for good.

"Breaking in" or seating a new set of rings to the bore is actually a process of "controlled wear".
If your rings aren't seating, you don't want to do reduce your rate of ring wear, you want to INCREASE it for short period of time.

You might try taking the car out and "standing on it".
Find a little used road, get the car into high gear with the engine at a low RPM, then put the accelerator to the floor.
Hold it there as long as is safe.
Slow down to a low RPM again and repeat the process.
Repeat, repeat, repeat, etc.

Driving the h&ll out of a car to seat the rings is something that used to be done quite often, and you'll even find reference to it in the book "Cast Iron Wonder: Chevrolet's Fabulous Six" by Doug Bell.

But... PLEASE BE CAREFULL !! :-)

I would think that I have put enough varied (city, mountain,& freeway) driving that the rings should have seated. That is why I wondered if it was maybe somewhat normal or too much oil up top. If I find a set of proper standard bore rings I will buy them and if I need to do any work on the internals will replace what came in it.

When I did the engine in my 1934 years ago I used some old stock piston rings and it smoked.It was freshley bored out to "040" over. After a couple of years I replaced the rings with another brand of old stock rings. Still smoke.
Next I looked up what more modern car had the same ring demension It turned out to be a 1950 Studebaker Commander. I ordered a set of rings from JCWhitney for about $12, things were cheaper then. The rings were made by Muskegon Piston Ring Company, the same as GM replacement rings. I used just the (chrome Plated) oil rings and reused the compression rings. No more smoke or oil c
onsumption
Usually broke in the rings on a highway higher speed trip to a meet..

Thanks for the information, I'll keep my eyes open for rings.

If you are at the point of being ready to tear down the engine a last ditch effort might be to try "dusting" the cylinders with an abrasive powder. I had a 60 chev 6 cyl that the rings would not seat in after rebuilding. . At the time I was attending a trade school for automotive tech and the instructor had me pull all the spark plugs and he dusted the cylinders with Bon Ami or a like product and within five miles the smoke cleared. Did an immediate oil change and another at 100 miles and had no further problems.

The Bon Ami in cylinders was used by many older mechanics in the 40s to 60s. I never used it but have listened to several that swore by it.

I have considered it. I won't open the engine until something breaks, it smokes but not that bad!

Ha Ha! :-)
I wasn't going to suggest that one!
Up here it was used more as a last resort to re-seat worn rings in well worn engines, and get a few more miles out of them.

My father used this trick to seat rings on naturally aspirated diesel engines. He would remove the intake manifold and let each cylinder suck in about a teaspoon of Bon Ami through the intake port.

He worked for a farm equipment manufacturer. They would have customers who would buy a new tractor late in the year after harvest and fall field work. Over the winter the tractor would be run in only light duty cycles so the rings would never get seated. When the farmer started spring field work they would complain about high oil consumption. The tractor would still be under warranty so they would use this as a step before taking the engine apart.

There are two possible things that may have caused the smoke. Either the rings lost their tension due to old age or not seated (worn in)' If tension is the problem replacement is the only cure. The production ring was a one piece cast iron ring with no expander behind it.
The expander type ring that Chevrolet sold for replaceent was part number 609961. Perhaps some ome has a set....try Bruce Bugay.

Well I purchased a set of McQuay-Norris rings and will decide a plan to use or store for a while. The Bon-Ami trick I have heard of, and may give it a try before an oil change. If that isn't helpful I have new rings to put in.

A problem with prepurchasing rings is that most times you dont know what size you need before lifting the head and measuring the bore. it is no use putting standard rings into a .010" oversize bore though with a little effort you can successfully put .010" oversize rings into a standard bore.
Tony

In his first post he said it was a new factory short block. They only came in standad sizes.