SAAC Forum

The Cars => 1966 Shelby GT350/GT350H => Topic started by: SHELB66 on August 07, 2025, 10:36:03 PM

Title: 1966 Tach Issue
Post by: SHELB66 on August 07, 2025, 10:36:03 PM
My 66 Hertz with original tach is having a repeat issue.  The first time it fixed itself.  What's happening is upon startup the tach registers 5000rpm at idle.  It will peg when given just a bit of gas.  I turned the engine off and on a couple of times but that didn't help matters.  The car was sitting outside today in the sun and the temp was in the mid to high 80's.  I'm wondering if excess heat might have been a factor.  Generally when I get too much sun I slow down, not speed up!  Any ideas?  Thanks!

Craig R.
Title: Re: 1966 Tach Issue
Post by: Bob Gaines on August 08, 2025, 09:24:17 AM
Quote from: SHELB66 on August 07, 2025, 10:36:03 PMMy 66 Hertz with original tach is having a repeat issue.  The first time it fixed itself.  What's happening is upon startup the tach registers 5000rpm at idle.  It will peg when given just a bit of gas.  I turned the engine off and on a couple of times but that didn't help matters.  The car was sitting outside today in the sun and the temp was in the mid to high 80's.  I'm wondering if excess heat might have been a factor.  Generally when I get too much sun I slow down, not speed up!  Any ideas?  Thanks!

Craig R.
Do you run a pertronix?
Title: Re: 1966 Tach Issue
Post by: JohnSlack on August 08, 2025, 10:05:52 AM
Bob, asked a good question, in addition it is my experience that electronic devices that are trying to tell you something is wrong don't fix themselves. You should listen, if it's not a Pertronix issue remove the tach and fix before the smoke gets out



John
Title: Re: 1966 Tach Issue
Post by: SHELB66 on August 08, 2025, 10:33:53 AM
No, I don't use a Pertronix.  I used the incorrect word when I stated the tach had "fixed" itself as obviously there's something going on that needs to be addressed.  I was just wondering if anyone else had experienced this issue.

Craig R.
Title: Re: 1966 Tach Issue
Post by: Bob Gaines on August 08, 2025, 10:41:07 AM
You will most likely have to send the Tach off to get it repaired. You probably already know this but in case you don't or for others reading that after you disconnect your tach to send off plug the two factory harness connectors together. That way your car will start and drive without the tach while you are waiting to get your tach back from repair.
Title: Re: 1966 Tach Issue
Post by: SHELB66 on August 09, 2025, 01:27:46 AM
Quote from: Bob Gaines on August 08, 2025, 10:41:07 AMYou will most likely have to send the Tach off to get it repaired. You probably already know this but in case you don't or for others reading that after you disconnect your tach to send off plug the two factory harness connectors together. That way your car will start and drive without the tach while you are waiting to get your tach back from repair.

Thanks for the heads up, Bob.  I'll make sure to do that.  Reminds me of the wired-in-series Rally Pacs that I used to deal with.

Craig R.
Title: Re: 1966 Tach Issue
Post by: Bob Gaines on August 09, 2025, 09:15:52 AM
Quote from: SHELB66 on August 09, 2025, 01:27:46 AM
Quote from: Bob Gaines on August 08, 2025, 10:41:07 AMYou will most likely have to send the Tach off to get it repaired. You probably already know this but in case you don't or for others reading that after you disconnect your tach to send off plug the two factory harness connectors together. That way your car will start and drive without the tach while you are waiting to get your tach back from repair.

Thanks for the heads up, Bob.  I'll make sure to do that.  Reminds me of the wired-in-series Rally Pacs that I used to deal with.

Craig R.
Exactly.