VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 1939 timing mark

Lately, I've been attending to the ignition health of my 1939 Master Deluxe 2 door. I had forgotten that the timing mark is on the flywheel and according to my 1942 Motors Manual, it is supposed to be a steel ball in the flywheel. I had a 1954 Chevy and I seem to remember that ball. My 1939 had a stamped triangle on the flywheel. I checked it and it very near TDC. I was wondering if this maybe a replacement flywheel. Has anyone else seen a timing mark like this. The car runs just fine using this mark. Any thoughts, Thanks Mike

My '39 had a steel ball and a triangle. I used the steel ball and fine tuned it using the octane selector to advance more to fine tune it. when too far advanced it will kick back or bind when starting.

My '37 was the same as Gene's '39. It had both the steel ball and the triangle. I cannot remember the significance of the triangle.

I set initial timing to the steel ball which is 5 degrees BTDC. I then added another 8 degrees with the octane selector. Gene is correct as always. If I went to 10 degrees on the octane selector it would kick back when starting, especially if the engine was hot from running.

Keeping in mind the timing specs were set for low octane gas I don't use the timing mark. I adjust to the fastest/smoothest idle with the octane selector on 0 and lock it down then adjust the idle back down if necessary. If necessary I fine tune using the octane selector. I haven't use a timing light for years.

Is the steel ball and the triangle in the same place? Is one TDC and the other the actual timing mark? I have peered through the timing hole quite a bit and have not seen the ball or any sign of one. Mike

On my ‘37 they were 2 separate items and not near each other.

The ball might be covered in lot of dirt and gunk. At a minimum there should be a hole if it fell out.

Once you find it you might clean it off and put a dab of white paint on it to make it easier to spot in the future.

This page may help you out: http://devestechnet.com/Home/StoveboltTiming

I cleaned the triangle and applied a little white paint. AND the triangle seems to be the timing mark, at least the engine runs fine when set to the triangle. I'll try looking for the steel ball again. I'll turn the engine over slow and watch. What is the purpose of two marks? Especially if they are not near each other? Thanks Mike

That is what I cannot remember. The triangle was there for alignment during assembly or something like that.

I found the ball on mine so l could clean it only after I removed the bottom flywheel cover. That is a really small window on the right rear of the block.

Now for another "I cannot remember." i do not know of the flywheel is indexed to the crank flange. If not and the flywheel was ever removed from the engine it might have been installed in a different position.

Well, I know for sure that the flywheel was removed. I did it maybe 50 years ago. Maybe tomorrow I can take the inspection cover off and look again for the steel ball. Thanks, Mike

One simple step is to remove the #1 plug and put a screwdriver down the hole. You should be able to see it rise and dwell at the top of the piston travel as you turn the crankshaft. Whatever mark is visible in the hole with the pointer on the right rear side of the engine is very close to top dead center.

For clarification that would be after the intake valve closes on the compression stroke the timing mark should be visible close to TDC. We might think of course that's obvious but what's obvious to one or even many isn't always obvious to all.

Tiny is correct with respect to ignition timing. I was only thinking about crank to flywheel position. #1 and #6 pistons should both be at TDC when the timing mark is at the pointer.

Well..... I finally got around to taking the inspection cover off and I found the timing marks. There is a steel ball. In fact there is a U|C then a short space then the steel ball and then maybe 10-15 degrees and then the triangle. My timing was set at the triangle and I had a low speed miss and what I thought was poor performance. After setting the timing correctly, the idle smoothed out quite a bit and the performance improved. I have to wonder what the U|C and the triangle are? And when the timing is set at the steel ball, what is the timing there? I doubt that the steel ball is TDC, I suspect it is some advance, but what. I suppose the next time the head is off I can try and measure it. Any ideas on the U|C and the triangle? The U|C is more advanced than the steel ball and the triangle is quite retarded. Thanks for the help, Mike

U|C is top dead center (Upper Center). The BB is a few degrees before U|C.

Thanks. I wonder why they didn't use TDC. And it is not expl;ained in the Service manuals I have for 1939, 41 or 42. Oh well, Mike

As I noted in my earlier post, the ball is 5 degrees before top dead center. That is defined in the Engineering specs.

Pardon me if I'm wrong here, but wouldn't the steel ball be 5 degrees 'after' TDC? The crank rotates Clockwise, so the steel ball will come to the pointer first then the U|C. To advance the timing, you have to rotate against the clockwise turning crank. At least this is how I see it. Mike

If you didn't take the link I posted above it makes some informative reading. http://devestechnet.com/Home/StoveboltTiming

Very interesting! Thanks a million. Mike