crab distributor on a 38 24 stud
 

is there an adaptor from 2 hole to 3 hole ditributor? I want to use the crab style on a 38ish 24 stud. I really dont want to pull the crank pulley and front cover unless that is the only way. what do you know? thanks for any ideas

Re: crab distributor on a 38 24 stud
 

Here's an adaptor from Speedway.

https://www.speedwaymotors.com/Flath...olt,25076.html

Re: crab distributor on a 38 24 stud
 

I feel the need to ask: "Why do you want to go the crab style?"

Re: crab distributor on a 38 24 stud
 

I changed to the 2 bolt cover this morning. but alas the snot on the camshaft is too long and the crab distributor won mount. looks like i would need something like a 7/16"spacer for it to work.

Re: crab distributor on a 38 24 stud
 

Gary, post #2, gave you the link for the adapter plate required.
I'd still like to know why you feel the desire to swap the original dizzy for the crab type.

Re: crab distributor on a 38 24 stud
 

If you've already swapped on a 2 bolt cover you need this spacer instead.

https://www.speedwaymotors.com/Flath...cer,25074.html

Mart.

Re: crab distributor on a 38 24 stud
 

Im with Kube. The three bolt 11a helmet distributor has the exact same advance curve as the 21a crab and performs the exact same and in my opinion given the distance between the bushings and the fact the rotor is in the middle of the shaft rather than attached to the end, I much prefer the helmet distributor as the bushings last longer in them over the crab.

But I can understand plug wire changes are much easier on a crab type as well as the cap and rotor.

Re: crab distributor on a 38 24 stud
 

You have offered a much more insightful reason why there is little advantage to swapping to the crab type dizzy.
Yep, easier to change the cap and wires for certain. Still, just how often are they necessary to change?
Of course, having no response from the OP doesn't help us better understand what he (or she) is envisioning with this proposed swap.

Re: crab distributor on a 38 24 stud
 

if its going in an Av8, the crab is shorter. no room to spare in those contraptions.

Re: crab distributor on a 38 24 stud
 

I found the crab, with external coil, easier to diagnose. The old saying, if it doesn't fire, it's usually spark or fuel. It is easy to take off the air filter to see if fuel is coming out using the accelerator pump. If there is no blue spark at the plugs, see if there is blue spark at the output of the coil. If so the problem is in the distributor mechanical rotor system; if not it is in the electrical system and it is a lot easier to change out the coil to see if the spark improves. Also, (and I say this in partial jest) since Henry went to this system, it must have been better to someone other than a restorer.

Re: crab distributor on a 38 24 stud
 

Juergen,

Just because the design was changed does not mean it would create a "better" distributor. There were considerations other than performance and service.

A helmet uses twice as much aluminum as a crab.

Aluminum production at the begining of WW2 was nothing compared to war production needs ... by war end the story was different.

Do your own calculations and figure out how many P-51's could be built from the aluminum saved.

(I could be wrong ... and didn't they make some crabs out of cast iron to save on aluminum?)

Re: crab distributor on a 38 24 stud
 

I would agree, knowing how Henry thought, that the Crab was at least 50% cost reduction but, I like them for 4 reasons. Looks (I grew up looking at them on all kinds of race engines), remote coil and they are easier to work on are 3. After market cams are another reason to use one.

I bought one and the aluminum gear, to put on my '36/'37, 21 stud stud engine, to use with the 59 style cam.