to bore the crank

bgarrett

bgarrett

Senior Member
How much of a big deal is it to bore the Model A crank for full pressure?
Is this something I can do at home with ordinary tools?

I have been working on old cars for more than 40 years and can fix just about anything except automatic transmissions and I have a lot of tools


edit: funny, I have been on this forum since before Shelley took over but I see this is my "first" post
 
Shelley"s long gone, new owners, BUT same great people reside here. Can't help you with your question though.
Paul in CT
 
bgarrett said:
How much of a big deal is it to bore the Model A crank for full pressure?
Is this something I can do at home with ordinary tools?

I have been working on old cars for more than 40 years and can fix just about anything except automatic transmissions and I have a lot of tools


edit: funny, I have been on this forum since before Shelley took over but I see this is my "first" post
Click to expand...

It is not a complicated job but does require an expensive machine to do it.
It is about a $150 dollar job at a machine shop.
 
Thank you for the reply, Pete.
What machine is required?
People have been doing this for 80 years, can it really be that difficult?
 
A cranks are harder to do than B cranks because you are more apt to drill out into air. I've never done one but know guys that have, a couple even did it with no guides. The difficult part is to get the hole to come out where you want it. Holes should line up so you have one hole at the center main, and centered in the rod. Pressure is not necessary unless you plan on turning high RPM, over 4,000 and/or put out lots of power. Most use 3/16" drill but 1/8" is adequate.
 
bgarrett said:
Thank you for the reply, Pete.
What machine is required?
People have been doing this for 80 years, can it really be that difficult?
Click to expand...

A vertical mill such as a Bridgeport is probably the most commonly used machine.
Some people use guide fixtures but that is not necessary with a Bridgeport type mill if you have the degree coordinates for the setup angles.
A carbide end mill is used to break through the hard outer skin and then drilling is quite easy with a 4 flute aircraft drill. The 4 flute drill will not "walk" off center like a standard 2 flute does sometimes.
 
I had my B crank done at Schwamms in Pa. Looks real good. When I got it back, the front gear was missing. I called them and a new one was sent with no hastle. Iceman
 
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