Tach drive question
Thread Starter
Instructor
Joined: Aug 2010
Posts: 187
Likes: 10
From: Western OK
Tach drive question
You might have seen my thread about a plug not firing which I have solved as the inducer ring had a magnet come loose.
My current question is about the tach drive. The tach stopped working awhile back and while I got the distributor out I figured why not fix it. This is on a 72 with a 350 and has one of those 90 degree adapters on it. I plan to reclock the distributor and do away with the adapter. When I pulled it off I was surprised to find that the gear on the cross shaft was in great shape as was the one on the shaft. I’m thinking it was the adapter that failed due to this. The shaft and gear both turn nice when I spin the distributor. Has anyone had one of those things fail?
I checked the cable and tach but spinning the cable with a drill and it was fine. What am I missing?
My current question is about the tach drive. The tach stopped working awhile back and while I got the distributor out I figured why not fix it. This is on a 72 with a 350 and has one of those 90 degree adapters on it. I plan to reclock the distributor and do away with the adapter. When I pulled it off I was surprised to find that the gear on the cross shaft was in great shape as was the one on the shaft. I’m thinking it was the adapter that failed due to this. The shaft and gear both turn nice when I spin the distributor. Has anyone had one of those things fail?
I checked the cable and tach but spinning the cable with a drill and it was fine. What am I missing?
Burning Brakes
Joined: Apr 2020
Posts: 781
Likes: 414
From: Western NY
They do fail. i've had them fail more than once and everytime the teeth get sheared on both the main shaft and the cross gear. check the gears closly for damage or excessive wear. if yours look good then reclock the dist and put it back in. should not need any 90* adaptor for it.
Thread Starter
Instructor
Joined: Aug 2010
Posts: 187
Likes: 10
From: Western OK
To end this mess I thought a follow up is in order. To use a NASA term. The car is stable.
seriously we got the new Petronix installed. Moved the distributor to match what the assembly manual shows with no issues. Of course we studied and calculated how far we had to turn the teeth to make it work. Actually it was a really easy as it started coming back to me as I had done this many times when I was a lot younger. Car fired right up so I called it a day as it was hot. I’ll get the car running good and timed then I’ll hook up the tach. I really think it was the 90 degree adapter than went bad which caused the tach issues.
This old guy greatly appreciates everyone help and suggestions.
seriously we got the new Petronix installed. Moved the distributor to match what the assembly manual shows with no issues. Of course we studied and calculated how far we had to turn the teeth to make it work. Actually it was a really easy as it started coming back to me as I had done this many times when I was a lot younger. Car fired right up so I called it a day as it was hot. I’ll get the car running good and timed then I’ll hook up the tach. I really think it was the 90 degree adapter than went bad which caused the tach issues.
This old guy greatly appreciates everyone help and suggestions.
