Super A timing

[CNKS]

Got the oil pressure plug in my Super A and reinstalled the front end and governor. Almost forgot the governor had to be timed to the cam gear. Decided I had probably disturbed the ignition timing, so decided to retime. I put #1 piston to the top of the compression stroke with my hand crank while watching the piston thru the plug hole. Decided to check the timing marks under the tractor. The mark on the flywheel was several degrees BEFORE the mark on the cover. When I aligned the marks, the piston was about a quarter inch down on the power stroke. Not sure which is correct. At running rpm, at least at idle if set by TDC it probably fires about TDC or earlier and advances with RPM. If set by the timing marks it will fire earlier yet. So which is correct -- or have I messed something else up. I always thought the marks were at TDC. When the engine was started when I was looking for the oil pressure it started easily and ran smoothly, more or less, but I do not remember which method I used when I first set the timing after the rebuild. Also this tractor has timing marks on the pulley as well as a pointer on the front cover off of a Super C (external_link.) It has double, single and a 4th mark (last) several degrees from the third. With the timing marks aligned underneath, the pointer matches the LAST mark on the pulley. Someone please clarify all this for me. I have always believed that TDC meant the timing marks were aligned in static timing. Perhaps not??

 

[Sam Eubanks]

Very interesting question. I would go with the tdc method over the timing marks. It may be that some parts were replaced. Just my thoughts. I am interested to hear the feedback from the experts as well.

 

[CNKS]

In the absence of any other replies, after thinking about it I'm going to answer my own question -- Not saying you are wrong Sam, I'm sure someone will let me know if I am wrong. I'm going to time it by the timing marks. Because, they do not have to be at TDC. The marks are there as a reference point, so that the engine will start, and then have the proper advance when running. I will put the engine on the compressin stroke, get the piston at maximum stroke, then continue to turn until the marks line up. The SA manual sort of says that, the H/M manuals say to continue turning until the marks line up. If I ignore the marks and time to absolute TDC, the advance at running will be too many degrees. I think. In any event, although several have disagreed previously it can always be adjusted by ear if it will start. Someone correct me. I may be reversing advance and retard in the above.

 

[ScottyHOMeY]

Hmmmm.... I've always found the flywheel mark to be true to TDC as in true position of the piton at TDC. There's only one way to mount that flyheel on the end of the crank, so there's nothing to misalign there. And I suppose if your rod bearings or wrist pins/bushings were worn enough you get could get some visible slop. You might could check for that by taking your flywheel mark PAST TDC then rolling the engine slightly backward to the mark and see if that leaves your piston near where it ought to be. Memory fails what you've ben doing with the motor, but a decent recent rebuild, what I'm thinking here won't be your answer.

Only other thing that comes to mind is whether the mark on the chassis might be off. On my BN, I've got the cast cover that has the nub cast in it for the flywheel mark to line up with. That cover lines up quite nicely withte bolts finger tight -- not much wiggle room.

My SuperC has the stamped steel cover there you line up with the vertical rib stamped into the cover. That cover has a lot more slop and movement in it when I put the bolts in finger tight when I go to put it back on. What I'm thinkin' here is that maybe that few degrees is not between the flywheel and the piston top, but simply a matter of the second mark, on the flywheel cover, being offset from the center because it cover is set off to the the side enough to make the few degrees difference you are seeing. I don't suppose one could rule out the stamping of that vertical rib being off-center either. If that mark is the issue, though, I'd sooner suspect the "float" of that cover on its mounting bolts over the stamping being off.

No solution, I'm afraid, just my thoughts for what they're worth.

 

[Achodges1]

I say use the marks. Thats what I did on my Super-C and it started right up, ran great, and still is.

 

[Tom Fleming]

CNKS, are you sure that the crank, cam, and govenor gears are correctly timed? I had an issue with my A where the govenor was out of time to the cam gear.

If these are not correct, you have a bigger issue. The govenor gear is easy to correct, you only have to take the govenor cover off and the distributor/magneto. if the cam gear is not timed correctly to the crank, you are back to removing the front cover..........

 

[CNKS]

Cam, crank, and governor marks line up. I did momentarily forget about the mark on the governor gear. If I hadn't remembered it would never start.

 

[CNKS]

I have the stamped cover, but the flywheel mark is WAY off, not enough slop in the cover for that to happen. As I mentioned above, I really believe those marks are nothing more than reference marks, to assure that the engine is in time for starting/running. With the mark on the flywheel lined up, the piston is about 1/4" down on the power stroke. When the engine starts, the advance likely puts the spark near the top of the compression stroke -- I assume --. As far as loose parts, the entire engine was rebuilt, with the except of the cam and valve train, machinest said cam was ok.

 

[teddy52food]

Something doesn't seem right. The factory mark on the flywheel is very hard to find. It is a faint line with a tc 1&4 by it. Maybe some one painted an advance mark next to it & you are confusing advance & retard and going by that mark.

 

[CNKS]

No, the flywheel is clean and the line is marked with white paint. It is correct.

 

[Ferd]

Don"t know about a Super A, but I just timed my 230 with a timing light. There"s marks on the front pulley and a pointer. Timing is about 30° BTDC according to the book and it runs great!

 

[LMack]

My manual said to align the marks on the flywheel then align the distributer over #1. The engine should then crank and allow for more refined timing of the distributor. On one occasion I was off one tooth on the distributor and the 200 still cranked but ran rough until I rotated the distributor. When corrected it ran fine. If you are able to crank the engine and it times out with the distributor cover clips horizontal, you have it timed correctly.