I am in the process of rebuilding my tach drive distributor out of the 71. While it is all apart, should I tap and insert a set screw in the hole leading from the nylon button to the exterior of the distributor housing? I understand the set screw can then be used to eliminate excessive end-play in the tach gear. How critical is this? If I do use the set screw, what should I set the end-play of the tach gear at?

Thanks,

Mike

 

Im in the process of rebuilding the tach drive distributor in my 74. I know there are places that put a oil impregnated bronze bushing in place of the nylon one. I would like to make my own but i need a good nylon bushing or a print of one can any one help. They dont wear out as fast as the nylon one. I looked around Mike and I cant find any specs on end play sry i couldnt help if I can find the specs Ill make you a bushing and send it to you.

 

I just rebuilt this one. Where is the nylon button you are concerned with?






[Modified by paul67, 8:14 PM 1/28/2004]

 

The nylon bushing goes in the housing that holds the tach drive gear.

 

Paul,

Here is a picture of my old nylon button and the hole that it resides in. It fits in the hole from the inside of the distributor and act as a soft stop for the end of the tach gear. As the button wears it allows the tach gear to start sliding back and forth. The idea is to tap this hole and insert a set screw that you could adjust to push against the button to control the tach gear end play.



Mike


[Modified by SLine78, 10:32 PM 1/28/2004]

 

lil ski,

I have a new nylon button coming as part of the repair kit I purchased from TLD. It included a shaft, tach gear, coupling, washer and button. I'll mic the button before installing and send you the numbers.

Mike

 

Mike,
I now realize why I was confused. The distributor I rebuilt does not have that hole! Interesting....FWIW, the tag on it tells me 1969 350/350 but as you know the tach drive distributors do not have stamped numbers as HEI units do and you can purchase a tag with any numbers on it you wish. So you just never know.

 

I just went through 3 tach distributors and had some problems you might want to be aware of.

First off I had to replace 2 main shafts and 2 cross gears. I ordered the parts from 2 well known suppliers and they both sent me the same style cross gear. This gear is black with a brass shoulder on it. They did not work with either the new main shafts or an original main shaft I have in another distributor. I was told that I had to "fit" the gear to compensate for housing wear. That's why the plastic buttons are there. I machined the face of the brass several times removing just .005" at a time and had no luck getting a smooth operation. If I tried it under load in the engine I'm sure it would have failed and taken out the main shaft too. I finally removed the brass button on th eend of the gear and installed a new one I made. Started over, same results. I returned all 3 cross gears I purchased,losing time and money in the deal. I was told I was the only one who experienced this problem, I find that hard to believe considering I bought from 2 vendors, but it's possible. There was no doubt the gear were the problem as I tried good used GM gears I have and they worked fine in every distributor that was binding.

I tried the set screw approach too and didn't like it. The housing on all of these were fine no dammage from the old gear. If there was then I would have set them up in a Bridgeport and spotfaced them. I did make up buttons out of bearing bronze(660) to replace the nylon buttons.

I also used a gear set made by High tech Innovations in FL 1-727-942-4003 they sell direct and make probably the best aftermarket gearset. The gears I returned were not made by them.

What should have been a simple part replacement/rebuild turned into a month long process of returning/ordering parts. I guess that's the case these days as it seems there are few replacement parts I get in that fit without some type of modification.

Do a search and you should find some info on this, I know Lars has put in a lot of time on rebuilding these and has responded in the past.

Good luck