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02-01-2020, 07:14 PM | #1 |
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2 bolt crab on a 21 stud question
Hi guys. I ordered a rebuilt 2 bolt crab distributor from Bubba. I have a 3 bolt cover and a 2 bolt cover. Can I just bolt the 2 bolt cover on and be good? My cam has a fiber pressed on gear. Just want to know what all I need to make the swap.
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02-01-2020, 07:24 PM | #2 |
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Re: 2 bolt crab on a 21 stud question
Nope, you can't just bolt it on. The distributor housing is "deeper" on the crab than on the authentic helmet style and as such the crab must be spaced outward to accommodate this.
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02-01-2020, 07:36 PM | #3 |
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Re: 2 bolt crab on a 21 stud question
speedway has the spacer. most, mine and others i have heard of, require a little trimming around the vacuum port. not a big deal, a few swipes with a file. i cant remember, but i think it hits a timing cover bolt or something. check the fit when you get it.
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02-01-2020, 08:51 PM | #4 |
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Re: 2 bolt crab on a 21 stud question
Here's the 2-bolt spacer at Speedway. Click the link below! DD
https://www.speedwaymotors.com/Flath...cer,25074.html |
02-01-2020, 09:00 PM | #5 |
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Re: 2 bolt crab on a 21 stud question
Ok cool that is not a bad price at all to make it all work.
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02-01-2020, 11:59 PM | #6 |
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Re: 2 bolt crab on a 21 stud question
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Here's a picture of the late, great Dick Spadaro's reproduction offering of a three bolt to two bolt adapter for mounting a crab style two bolt distributor on an original three bolt timing gear cover used from '32 to '41.
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John "Never give up on what you really want to do. The person with big dreams is more powerful than one with all the facts". Albert Einstein Last edited by JM 35 Sedan; 02-02-2020 at 11:25 PM. |
02-02-2020, 10:34 AM | #7 |
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Re: 2 bolt crab on a 21 stud question
I run a crab distributor on a 3 to 2 bolt adaptor on the 21 stud Pilot motor in my 33 coupe.
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02-02-2020, 09:40 PM | #8 |
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Re: 2 bolt crab on a 21 stud question
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02-13-2020, 09:24 AM | #9 |
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Re: 2 bolt crab on a 21 stud question
You can also run a late style 49/53 dist with a gear drive adapter and the late front cover. However your cam protrudes out from the cam and the adapter must be clearanced or the cam ground down.. Not an easy project. and the crab distributor is a good one.
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02-25-2020, 06:49 PM | #10 |
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Re: 2 bolt crab on a 21 stud question
Hey guys if I am going for optimal clearance, meaning distributor as close to the cover which one do I use? I have both a 3 and 2 bolt cover. I think the 2 bolt cover and spacer will get me closer to the engine. Reason I ask is because I am running a ‘46 crank gear, fan with hub and generator. I don’t want the crab pushed out to far to interfere with the fan belt.
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02-25-2020, 07:12 PM | #11 |
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Re: 2 bolt crab on a 21 stud question
Vanspeed: What cam do you have in it? If the 46 type cam then the 2 bolt cover and the crab dist. will bolt right on. No spacer required.
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02-25-2020, 07:20 PM | #12 |
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Re: 2 bolt crab on a 21 stud question
Just looked and it is the press on type fiber cam gear.
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02-25-2020, 07:20 PM | #13 |
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Re: 2 bolt crab on a 21 stud question
So you're running a '46 front crankshaft gear on....which year crank shaft?? So...which cam and camshaft timing gear are you actually using in your 21 stud engine?? There are what's known as long and short cams, and depending on which one you have, will determine if you need a distributor spacer or not. Your first post says... press on fibre timing gear, which usually/normally means you have the long style camshaft, but let's make sure before we attempt to answer your last posted question....
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02-25-2020, 07:23 PM | #14 | |
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Re: 2 bolt crab on a 21 stud question
Yeah I know you are thinking why a ‘46 crank pulley and fan? I am fitting a 36 LB engine into my ‘29 A coupe and I needed a mechanical fan that was in the center of my radiator.
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02-25-2020, 07:26 PM | #15 |
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Re: 2 bolt crab on a 21 stud question
In that case the two bolt cover with the spacer or the three bolt cover with the three to two bolt adaptor will both give the same result. They are both designed to mate a crab distributor to a long nose (as in 21 stud with a pressed on fibre gear) cam.
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02-25-2020, 07:37 PM | #16 |
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Re: 2 bolt crab on a 21 stud question
So they both then must push the dizzy out 3/8 of an inch then correct? To me the 2 bolt to 2 bolt spacer is better looking than the 3 bolt to 2 bolt spacer. I didn’t know they both push the distributor out the same amount.
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02-25-2020, 08:35 PM | #17 |
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Re: 2 bolt crab on a 21 stud question
The only advantage that I can think of at the moment, with the 2 to 3 bolt spacer, 3 bolt timing gear cover is...if your ever wanted to quickly go back to a 3 bolt helmet distributor. Which is the best way for me, since I carry both 2 and 3 bolt distributors when I'm on long distance, possibly cross-country, tours.
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02-25-2020, 08:56 PM | #18 | |
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Re: 2 bolt crab on a 21 stud question
I don’t think I could ever get a stock helmet back on because of the ‘46 fan setup.
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02-25-2020, 07:39 PM | #19 |
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Re: 2 bolt crab on a 21 stud question
Vanspeed, you said '46 crank gear....so I'm guessing you really meant '46 crankshaft pulley?? Or am I confused??
"Correction, I thought you were looking for max fan to distributor space for using a crab vs. helmet type distributors. I believe the crab style distributor with spacer would give you the most space between fan and distributor, with your present engine construction. So, if you're only talking crab distributor and long cam, the best you can be is whatever space you have using the crab and one of the two spacers, with the appropriate timing gear cover. To get the maximum space, you would need to go with the short cam, bolt on camshaft timing gear, and two bolt timing gear cover, as I believe Mart has already said.
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John "Never give up on what you really want to do. The person with big dreams is more powerful than one with all the facts". Albert Einstein Last edited by JM 35 Sedan; 02-25-2020 at 08:47 PM. |
02-25-2020, 08:57 PM | #20 | |
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Re: 2 bolt crab on a 21 stud question
Yes sorry crank shaft pulley, not gear. My mistake.
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