Viberation - After Installing Model B Distributor

Mike A Model

Mike A Model

Member
My objective was to replace my existing Model A distributor with a Model B distributor on my 1928 Roadster. I found a Model B distributor, sent it out for a complete rebuild and after a long search, found a good Model B timing gear cover. I replaced the Model A timing gear cover, which bolts directly to the front cross member, with the Model B timing gear cover and used the Model A thrust plunger and spring. As expected, when I removed the Model A timing cover it damaged the oil pan gasket. This however gave me the opportunity to clean and inspect the oil pan. Well, while I had the oil pan removed, I figured this would be a good time to rebuild the oil pump with new gears, screen and bushings. Which I did. Too make a long story short, after completing the work it was time to start the motor, which started and sounds good at idle. I decided it was time to goose the motor a little, when I did the vibration shook the headlights, fenders and any other loose stuff. Kind of troubling, in that before I made the changes the motor had some vibration, as with all A motors, but not like this. The only rotational change I made was to the oil pump. Any advice would greatly be appreciated.
Thank you,
Mike
 
I don't know the answer to this, but is the timing gear for the Model B engine different than the Model A? You mentioned a Model B timing cover which I seem to remember reading that the timing pin hole is in a different location than the Model A. I guess to be sure, rather than setting TDC using the timing pin, look down the hole of #1.
 
If you replaced the timing cover with the motor in the car you might have damaged the rear motor mounts. I would start with trouble shooting by checking motor mounts first.
 
I want to thank everyone for their comments:

1. It is a two-piece distributor shaft, I used the existing Model A shaft. What should I be looking for?

2. When I raised the motor to replace the timing gear cover, I removed the rear motor bolts so it would pivot when I raised the motor.

3. Question: When I replaced the bushings in the oil pump, I could turn the shaft by hand, and it did not feel like it was binding. However, could the bushing be enough out of alignment to cause a vibration at a higher RPM?

Mike
 
It sounds like the timing is too far advanced.

Try backing it off a few degrees.

Also, since the timing is automatically advanced with the speed of the motor, it will not sound/react the same as before.
 
If I understand things correctly, with the B cover you are firing 19 degrees BEFORE top dead center to start with, and the centrifugal advance only gives something like 7 degrees more when running. I don't think bushings that were replaced in the oil pump have anything to do with this. The reason for the two piece shaft is to take care of any miss alignment. If you have not taken time to read the links I posted I would take the time to read them. I think this sounds like a timing issue.


Are you sure it is a B cover? If it was a B cover drilled for Model A, a replacement, then you would only be getting approx 7 degrees advance.
 
Redmodelt, thank you for your suggestions and the attachments. I compared the Model B cover to the A cover and could see the different in the pin locations. I feel sure it is a Model B timing cover. This afternoon, I am going to retime the motor following the procedures from your attachments and will report back.

Mike
 
redmodelt said:
If I understand things correctly, with the B cover you are firing 19 degrees BEFORE top dead center to start with, and the centrifugal advance only gives something like 7 degrees more when running. I don't think bushings that were replaced in the oil pump have anything to do with this. The reason for the two piece shaft is to take care of any miss alignment. If you have not taken time to read the links I posted I would take the time to read them. I think this sounds like a timing issue.


Are you sure it is a B cover? If it was a B cover drilled for Model A, a replacement, then you would only be getting approx 7 degrees advance.
Click to expand...

The B distributor has not 7 but 12-13 degrees of advance from the initial 19 degrees. A rusty and worn B distributor will tend to give less advance.
 
ursus, Thanks for the correction. I knew the first part was correct and was hopping someone would correct the 3ed.
 
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