Timing issues

Ken B

Ken B

Senior Member
I am stumped with a timing issue and hope that more veteran Model A'ers on this forum can help. When I use the Les Andrews method to set the timing, I can get the trouble light to come on within two to three clicks down on the spark rod from fully retarded. The engine still runs a bit sluggish and doesn't sound right. The rotor is already past the pin on the distributor body for cylinder number one, almost a good 1/4". I went as far as pulling the timing gear cover to make sure the dimples line up on the timing gear and the cam gear. This engine was totally rebuilt. In the past, the rotor would be pointing right at the front of the pin for cylinder number one using the trouble light method on my other Model As and run very smooth with lots of power. I have tried a new distributor cam, points, capacitor, and even upgraded to a modern upper plate. I have made sure that the steering column is adjusted to have the spark rod push the distributor arm all the way to the stop when it is in the fully retarded position. The coil polarity has been checked and is correct. The plugs are new and gapped correctly. What else am I missing here? What else can I check/adjust? Thanks in advance for any advice. Ken B.
 
" I have tried a new distributor cam, points, capacitor, and even upgraded to a modern upper plate. "

I never considered changing to a later style upper plate an "upgrade". I've only thought of it as an unneccessary change.

It sounds like your timing is late. As you very slowly crank the engine over the timing pin will drop into the timing dimple and as it does, the points should just start to open for #1 cylinder with the timing lever all the way UP.
 
I think I recall reading that some of the "modern" upper plates have the points in the wrong place. I would think that the rotor tip should be close to centered on the distributor body pin, preferably about around half advance. Certainly the rotor tip should not be actually past the pin. Did you also have the problem with an original plate and points?

Sounds like you have covered everything else I can think of.

Joe
 
When I first bought my Model A, I also seemed to think that maybe it would be better to go to the "modern upper plate". I fiddled with it, still not quite right, then took it over to a Saturday work session with other Model A club members, and asked them for help. They soon yanked that plate and put the original one back in. Seems most Model A guys prefer the original...I know it is much easier to adjust the points when necessary. I would recommend you go back to the original type.
 
Maybe the backlash is what is causing trouble. Make sure the cam is so near opening the points that if you breath on it it will open them. And remember, the rotor turns counterclockwise. I saw a doodlebug timed as if the cam ran clockwise and it was very sluggish. After you finish the adjustment, turn the engine with the crank a full 2 revs and be sure the cam is exactly where you want it without you actually touching the dist shaft in any way.
 
Richard in NC said:
Maybe the backlash is what is causing trouble. Make sure the cam is so near opening the points that if you breath on it it will open them. And remember, the rotor turns counterclockwise. I saw a doodlebug timed as if the cam ran clockwise and it was very sluggish. After you finish the adjustment, turn the engine with the crank a full 2 revs and be sure the cam is exactly where you want it without you actually touching the dist shaft in any way.
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Richard has a good point about backlash. Attached is a picture of my distributor drive gear which was the culprit on Dad's old coupe. These are not at all hard to change but I did have trouble getting good repo parts.
 

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  • Oil pump - Distributor Gear.jpg
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Also, check to be sure that a B motor timing gear cover was not put on by mistake. I was working on a car recently and we coudl not get the timing exactly right. Turned out the timing gear cover was a B.
 
The distributor drive gear is also new with very little backlash. I have had the same issue with the original upper plate as well. I have had no luck with the reproduction points and wanted to try the modern upper plate as a try to get the points to last longer. Even with cam lube, the points wouldn't last more than 100 miles before the wear bar was shot. I've also tried two different new distributor cams. The saga continues. I must be missing something simple---I hope. Ken
 
Brian,
I am pretty sure that the engine rebuilder used my old timing gear cover. But, How would I check this? Is there a special marking on it? At this point, I need to check and verify all possibilities. I did pull the #1 spark plug and verified that the piston is at the top of it's travel when the timing pin is in. How far off of top dead center would a B cover be with the timing pin set? Thanks, Ken
 
as mentioned by Richard, are you sure you are setting timing with the points on the leading side of the cam, which turns counter clockwise? With the original top plate or correctly indexed reproduction, the relationship of the points, cam and contact should always be such that the lead edge of the cam at the point block should coincide with the trailing edge of the rotor pointing at the contact when the arm is fully against the retard side of the window in the distributor body. The only way to change it is to move the points by moving the plate. This relationship stays even with the distributor out of the car. If the cam is correctly positioned at the points and the rotor is not pointing the following edge at the contact, then either the cap , the plate or the cam is made wrong. However, with the following edge of the cam just leaving the points, the rotor will be a small distance away from the contact as you describe.
 
pat in Santa Cruz said:
The distributor body contact should point at the trailing edge of the rotor with the lever at the top of the register. I suspect the "Modern improvement" upper plate is performing in a similar fashion to most improvements to the original design. Follow this link to the best tutorial on timing:

http://www.abarnyard.com/workshop/timing.htm
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Ken,

The picture in the above internet link is excellent at showing the rotor position at TDC. Check it out and see if you have the same rotor position. From your words, I think that you have it wrong.

Marc
 
I have used this tutorial and the rotor still is past ( a good 1/4 inch ) the #1 contact on the body. This is the first time I have run into this in over 25 years of working on Model As. I always remember the rotor tab a lot closer to the #1 pin when timed correctly. I am wondering if the reproduction body isn't cut correctly for the upper plate arm that attaches to the rod. This would give a false setting on the fully retarded position. I'll keep you all posted.
 
Just a stretch on my part, but is it possible your distributor is 180* out? I think, although keyed offset, it is possible to have the offset shaft in 180* out.
 
i use a timing plate & lite . ez & correct . to do it the old way will get you close , but timing it with a lite gets it correct ................ steve
 
steve norcal said:
i use a timing plate & lite . ez & correct . to do it the old way will get you close , but timing it with a lite gets it correct ................ steve
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I friend of mine insisted the same thing so I timed his "A" the same as I always do. He hooked up the timing light and it was within one degree. Of course I don't set it retarded like the folks have described from their favorite books.
 
One question still needs to be answered. It was mentioned that new points and cam were installed and cam lube was used but the rubbing block wore out within 100 miles. What would cause this?
 
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