Crab Distributors

[Bob NH]

NAPA and I'm sure others sell a package of various thickness gasket material. I make many that are otherwise not available.

[BUBBAS IGNITION]

After building a few hundred crabs for customers i too have the found the gasket impossible to source and use. I use either a NAPA cap and rotor or the set from Third Generation parts. Neither comes with a gasket. I do have a couple Mallory caps with a small gasket.

The crab as well as the helmet is vented . The crab has a vent hole in the lower part of the distributor housing.

Ignition caps shouldnt be totally sealed as the engine will create a vacuum and spark will jump easier in a vacuum causing a misfire.
I suggest spraying some WD40 inside the cap , spray the wiring and drive them....

[34fivewindow]

Here is the gasket for the crab cap, I buy gasket kits from C&G Ford Parts.

[flatjack9]

I have found that the crab cap is a pretty tight fit on the distributor and so I'm not particularly worried about a leak. At least not in 20 years.

[JM 35 Sedan]

With all due respect to those who profess no gasket (or other means of sealing) is necessary between the cap and casting on a crab distributor, I'd have to disagree. From my experiences driving these early Ford V8's with front mount distributors, I would suggest a good means of sealing caps, and other areas where moisture can/will enter the main housing.

[Drbrown]

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Have the single-piece crab cap on my '47. Didn't have a gasket between the cap and metal body when car purchased. Never any problem. Once found a 3-piece distributor gasket set on Ebay. Later lost that particular gasket. Bubba's opinion - not really necessary for me so I continue to run it without the gasket.

Bubba and Charlie NY can furnish all those parts.

Note: As Bubba and Charlie will tell you, file-down the brass end of those stock rotors as most of them may hit and brake your cap. Broke two new caps on mine until I one of them informed me. Bubba does that for all the crabs he sends out.

[38bill]

19 years on the road with some heavy rain and no gasket on the crab cap. No problems yet but then I'm not driving through deep water.

PS: I seem to remember that Rumbleseat recommended that you spray the distributor with some clear lacquer to help waterproof it.

[Ritzy1]

Sorry if I hijacked this thread. Everyone's input is much appreciated. I'm not going to worry about that gasket any more. Bigger fish to fry!

Drbrown's post is spot on. When Jim had my distributor on his machine, he had to file down the rotor as it was hitting the cap.

[Bob NH]

Curious about this filing down of the rotor ? How would a person determine how much to take off if you thought it needed to be done ? I had the dist. in a vise yesterday with new rotor and cap installed and turned very slow and felt no resistance all the way around, I did however file just a tiny bit from each side of the rotor brass hoping it would not catch something when going around the cap.

[Mart]

I suppose (haven't tried it) but you could take an otherwise scrap cap and drill some big holes in it so the rotor is visible as it rotates.

Mart.

[BUBBAS IGNITION]

Originally Posted by Bob NH

Curious about this filing down of the rotor ? How would a person determine how much to take off if you thought it needed to be done ? I had the dist. in a vise yesterday with new rotor and cap installed and turned very slow and felt no resistance all the way around, I did however file just a tiny bit from each side of the rotor brass hoping it would not catch something when going around the cap.

Bob,

Typically i use the Echlin cap and rotor. After a rebuild i install the cap and rotor then turn the rotor with my hand . Often the rotor will lightly strike the contact, the fix is a quick brush on the belt sander.
Now days i belt sand them all just to make sure . This removes very little off the tip and if anything would help the ignition..