limited swing on spark advance

K

klrh20frank

Member
1929 coupe
I only have about 1/3 swing in the distributor window when moving the spark rod from full retard to full advance. The 1-3 movement is near the center of the window. is there a way to adjust this on the 28-29's. thanks for your assistance.
Frank
 
the only time this happened to me was with an aftermarket spark advance rod.(the little rod that connects from the distributer to the column).
i was going to shorten it but i used an original one instead.

if you unhook that rod and move the advance on the distributer by hand does it move through the whole travel of that window.
same with the lever on the column check that it has free movement.
 
If your '29 Coupe has the two-tooth steering box, loosen the clamp bolt just above the steering box and the two gas tank clamp bolts. Then rotate the steering jacket to set the spark rod travel inside the distributor body window so that the upper plate arm touches each extreme of that window. Test and then re-tighten the bolts. Being a '29, your Model A has a 50-50 chance that the steering box is the two-tooth version.
However, if your steering box is the seven-tooth design, you can't make this adjustment. You could file the window in the plastic distributor body to expand the range of movement. As recommended, try different length spark rods.
Marshall
 
One other thought - Try bending the little spark rod arm on the steering column. It may be bent or have been incorrectly installed during a past restoration.
Is the spark lever on the quadrant making its full travel from click to click? Sometimes that rod gets gummed up in the upper bushing and will not make the full travel.
Marshall
 
The "slot" in the distributor cap determines the "range" of spark adjustment. There is considerably more adjustment available in the linkage, apparently to accommodate the "assembly tolerance" as described by Marshall.

Vince Falter (Fordgarage) https://www.fordgarage.com/pages/bdistributoradvance.htm

Compare this to a Model A distributor which has an initial timing point at 0 crankshaft degrees TDC plus an actual manual maximum advance of 40 crankshaft degrees (via the advance lever on the steering column). The notch in the bakelite distributor body for the arm of the point breaker plate limits the travel of the plate, and thus the manual timing advance.
Click to expand...
I bought what I thought was a nice RED distributor cap on ebay for small money thinking that might look nice on the early AA truck. I should have examined my purchase before popping the wallet - the cap has been cut to give the FULL span of the distributor - making it difficult at best to get to Vince's "initial sweet spot."

It still looks nice but I have to time the engine with an uncut cap, define the "arc" of proper hand adjustment in my mind, and then swap the cap back. I'm thinking of gluing in a segment of black cap and using it the "normal way."

Joe K
 
Sorry i have been so slow in looking at the comments. I had a heart valve replaced but doing a lot better.

1. will check the throw of the advance with the spark rod disconnected at the steering column

2. how wide should the cutout be ?

3 i have some other distributor bodies. I check the width cut out on several.

Thanks for the comments.
frank
 
Back in from the shop.
i, found that the spark rod is about 1/4 inch from the top when full retarded.
2. the throw of the advance in the distributor is about 21 degrees.
 
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