New "B" Distributor Cam

Ron in Quincy

Ron in Quincy

Well-known member
Last weekend Les Andrews and I spent 2 hours checking out a timing problem.

As it ended up, "WE Couldn't See the Forest for the Trees". Felt I should share the problem we found with you.

For additional information, the Distributor was completly rebuilt, no back lash, less than .001 variation on the point openings and points set at .018.

We started out inserting the timing pin to establish "Top Dead Center", even pulled #1 plug to verify the piston was at top dead center. With spark retarted made sure the points were just starting to open; set so one click on spark rod the points opened.

When we installed the rotor it was pointing 1/16" beyond #1 contact in the distributor body. We changed rotor, went thru the timing process again, NOTE: The front timing case cover had been previously removed to determine that the marks on the timing gear and crankshaft gear were correct.

We finally concluded the problem must be the "CAM". I had another rebuilt distributor that had a original A cam. We removed the A cam and reinstalled it in the distributor on the engine.

Guess what !!!! the rotor was now pointing to #1 contact .

The problem was the new "B" ground cam; the slot the rotor engages was cut in the wrong position on the cam locating it in a advanced condition.

Ron
 
Interesting! Any idea of the source for the cam or is there only one manuf who supplies all the vendors. I recently installed one. Thanks in advance.
Paul in CT
 
Had the same problem here, Rebuilt a disy for friend & no way could he get the engine to run, did fit mod points , after checking found top NEW shaft had 5 thou out of round so gap on points fine on three lobes but way out on one, still no go, closer inpection found cam notch out, so rotor was of line, exchange for another new one which was ok, Parts house correcting & replacing the out of round top shafts, Some quality control is needed, shaft was USA made ??but who machined it ??
 
1931 flamingo said:
Interesting! Any idea of the source for the cam or is there only one manuf who supplies all the vendors. I recently installed one. Thanks in advance.
Paul in CT
Click to expand...

I am pretty sure there is still two suppliers for the 'B' cam, ...but only one good supplier. The one you want is the one manufactured by Bill Stipe (29redrocket).

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I had a similar problem and it ended up being that the distributor body cutout for the spark rod was in the wrong position. With the spark rod fully retarded, I went through the timing procedure and still couldn't get the engine to run right. I compared an original body and the opening was off by about a quarter inch. With the original body, the engine timed out great. Just another example of poor reproduction quality.
 
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