Unusual 1967 427 390 Distributor?
I've been trying to find a Tach gear to replace the chewed up one in my distributor and haven't had any luck finding one like it. The tach gear shaft has a small hole in the end that inserts into a tiny nipple or shaft that is machined into the side of the distributor housing. I sent photos to the technical staff of a large Corvette parts supplier and they informed me they have never seen anything like it. They said there is supposed to be a nylon button in there for the tach shaft to ride against. I'm posting photos of the tach gear, distributor housing and build tag. If anyone has any information on this particular distributor I would appreciate it. I've had this Corvette since it was new and this is the first time the distributor has been out of the engine. Help!
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Re: Unusual 1967 427 390 Distributor?
that is not machined there it is worn there and you will need to install a bronze "button" https://www.paragoncorvette.com/p-34...ar-button.aspxLast edited by Clem Z.; October 31, 2010, 03:50 PM. -
Re: Unusual 1967 427 390 Distributor?
Are you sure, Clem ? Just checked one that's on my bench. Stuck a toothpick in the cable hole and sucked up the tach gear; then rotated the distrib. shaft as in operation (clockwise when viewed from above) and the gear moved in towards the cast iron housing.
Also worth mentioning for Don and others; GM did not install the nylon (?) thrust button in production until about mid-calendar 1970 IIRC.Last edited by Wayne M.; October 31, 2010, 05:38 PM.Comment
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Re: Unusual 1967 427 390 Distributor?
Donald,
What's so different about this distributor. Clem is right in that the gear has wore into the distributor housing and needs a bronze button to repair. The thrust of the gear is in toward the housing so this is where the gear wears perfectly into the housing and looks like it's supposed to be there. It's funny that the thrust washer is on the other side and I suspect it's there to protect the bronze bushing but the thrust is in..
Install the bronze bushing and get a drill bit that fits just snug into the hole and use it to make a drill start inside the distributor hole. This will remove the pretty dimple in the middle and provide the center of the small hole you need to drill for the button. Check the archives for info and probably pictures..
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Re: Unusual 1967 427 390 Distributor?
never checked this but with the little washer on the gear on the screw in bushing side i assumed the thrust was towards the washer. we shimmed the gear for end play using a set screw with a lock nut thru the housing to stop the stripping of the gears.Last edited by Clem Z.; October 31, 2010, 06:28 PM.Comment
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Re: Unusual 1967 427 390 Distributor?
If you are careful, you can drill the hole to a depth slightly less than the thickness of the casting, and adjust the pin length on the brass button available from the normal Corvette outlets to be just less than the depth of the hole, when using the brass button, most times you will have to remove the shim between the threaded brass collar and the crossgear to prevent binding.Bill Clupper #618Comment
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Re: Unusual 1967 427 390 Distributor?
Thanks everbody for all of the information. I didn't want to make any modifications to the distributor housing until I found out whether this is some kind of prototype that was stuck into my car by accident. I've heard of wierd things like that happening. It's hard for me to imagine how the tach shaft cut into the distributor housing about 1/8 in. and left a tiny shaft protruding into the hole in the tach shaft. I have a little over 30k miles on the car, so I suppose it's possible. Looks like the best thing to do is drill the hole and go with the button! Thanks again!
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Re: Unusual 1967 427 390 Distributor?
Donald-----Thanks everbody for all of the information. I didn't want to make any modifications to the distributor housing until I found out whether this is some kind of prototype that was stuck into my car by accident. I've heard of wierd things like that happening. It's hard for me to imagine how the tach shaft cut into the distributor housing about 1/8 in. and left a tiny shaft protruding into the hole in the tach shaft. I have a little over 30k miles on the car, so I suppose it's possible. Looks like the best thing to do is drill the hole and go with the button! Thanks again!
I have seen this same phenomenon on quite a few distributors. While it may be hard to believe, the tach cross gear is what created the circular depression and central "pin" that you see. The tach gear is quite hard and the distributor housing is quite soft.In Appreciation of John HinckleyComment
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