[69GP1]

I bought what supposedly is the best repro tach on the market, and have trouble with erroneous readings and/or no reading at all. I sent it back, and they checked it out... said it was fine and returned it. It worked for while, then reverted to the same thing. I bought ANOTHER and tried that, but got the same results.

Since then, I read that the tachs won't work with some aftermarket ignition systems like Mallory, etc. I put Pertronix on my car. Could this be the problem?

It works fine at times, then gets erratic and sticks at 4000 RPM or shuts off. The ground is good, the light works perfectly. It's grounded to the horn really mount screw as per the factory diagram.

Are these repro tachs junk, or could it be my ignition?

Does anyone else have a hood tach and the Pertronix module?

Thanks...

[jwcfbd]

I have the same setup and at one point I was having problems like what you are having now. I got water in my tach which caused some corrosion on the board inside it. I took it apart, cleaned it all up and then completely covered it with clear silicone. It's been working ever since.

[69GP1]

Thanks, JWC.

Did you use RTV type silicone, or some kind of liquid spray?

I'll give it a try, but I dread taking down the hood pad, those clips are a pain!

[jwcfbd]

Originally Posted by 69GP1

Thanks, JWC.

Did you use RTV type silicone, or some kind of liquid spray?

I'll give it a try, but I dread taking down the hood pad, those clips are a pain!

I just used the RTV type. I guess I'm lucky that I don't have a hood pad to worry about.

[F ROCK]

I had an issue with an accel points elim and a sun tach... burned up the tach.
I went back to points!
I use the py hood tach I think its the best...its def the best of the ones I have.

[Sun Tuned]

Had a customer here that I did a dist for but it was points.

67 with a hood tach. Damn thing like to have driven me and him nuts till he figured out everything ran super swell till the hood tach was connected.

He forgot to hook it up one day while troubleshooting what he had just paid me to work on and we both were leaning towards a condenser failure, since I had shipped it.

Turns out he was going down the driveway and all was swell and in his joy he noticed the tach unhooked and not working..... soon as he jumped out and reconnected it, all the problems appeared again ....disconnect it and they went away.

Never did learn what the problem with the tach was, but they sure can cause probs.

[PMD1969]

Originally Posted by jwcfbd

I have the same setup and at one point I was having problems like what you are having now. I got water in my tach which caused some corrosion on the board inside it. I took it apart, cleaned it all up and then completely covered it with clear silicone. It's been working ever since.

Why not use one of the repop vent kits?

[Sporter]

http://m.summitracing.com/parts/msd-8920

I had to use a tach adapter to get my hood tach to work with a Petronix kit. Works for MSD and Crane kits as well.

[ELKHORNAOG7]

I have an aftermarket hood tach I got 5-6 years ago from py and hooked it up to a pertronix dist. and had no issuses at all with it, I just used the wires that came with it but on my tach. I would have to have the wire for the light hooked up at all times if not it would not work ------BOB

[jwcfbd]

Originally Posted by PMD1969

Why not use one of the repop vent kits?

I didn't know there was a vent kit.. Mine just wasn't sealed very good when I got it and to top it off I hit it with the pressure washer. Once I took it apart, dried it out and resealed it, it's been fine.