VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 smoke on start up

This not really a question as to why it smokes but the repair.
The smoke comes from the pistons being plugged behind the oil ring,I've read where on repair articles mention installing aluminum pistons rather than leaving the old cast iron pistons .
I really only want to do this once ,.So use the old pistons or order new ? What type of rings work best?

The most common cause for start-up smoke is oil running down the valve guides.Prior to 1941 tere was nothing to prevent the oil from running down the guide. In 1941 they placed a metal hat over the top of the valve spring retainer and tip of the valve. This helped a little. From 1942-1947 they came with the hat over all the vaalvs. Often they were removed becasue as they got older the made the valve train more noisy.
In 1948 they went to the two grove valve, one grove for the keeper snd one for a rubber "O" ring. This was also used on the 8 Cyl. engines for many years.
My 1939 smoked like this after I overhauled the engine years ago. I installed the plastic shedders that were used in the Ford 3302 engine. Necessary to remove the keepers and cap and slide the shedder over the valve stem. It prevents the oil from reaching the guide - which really dosen't need oil any way. This will also reduce oil consumption.
The rings usually do not cause the smoke as the oil on the side of the piston drains down when engine is stopped and does not drain up into the combustion chamber.

Gene,
did you install them only on the intakes?

I put them on all the valves. I did te same thing on my '34.

My 1939 smoked like this after I overhauled the engine years ago. I installed the plastic shedders that were used in the Ford 3302 engine. Necessary to remove the keepers and cap and slide the shedder over the valve stem. It prevents the oil from reaching the guide - which really dosen't need oil any way.

Chey Nut....I don't understand your statement "the valve guide doesn't need oil anyway"

When I got my 38 It run like crap....4 push rods were bent and their valves were stuck. After I looked it over real good I found that someone along the line installed 2 Set's of valve seals...First they put in "O" rings and then rubber caps over the top of the valve guides....I removed all of the valve seals.
The 38 shop manual states 3 times, in the engine section, the importance of the VALVE GUIDES & STEMS getting oil to keep the valves from sticking. After removing the seals the engine runs great and I have had no other problem with the sticking valves.
I always add a quart of MMO when I change oil and the engine burns very little oil...nothing to be concerned about.
I much rather burn a little oil then have the valves sticking all the time....ED

I agree with ED1938. The valves and guides need some lubrication.

From 1941 (on intakes) 1942 up to the present daythe guides recieved no lubrication,....with not increase wear on guides or stems. Modern cars can go 300,000 miles with "dry" guides.
The oil running down the guides can cause carbon to form on the valve stems resulting in sticking valves which was always a problem on older Chevrolet engines. Check the valve adjusting instructions in the older shop manuals regading sticky valves.
I have had no stuck valves in my cars running dry valves. The ones that do have problems is on engines where the rebuilders left too little clearence on the stem to guide spec. When the engines got good snd hot the valves would hang up.