Tach Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**WorkinLonghorn** · 01-08-2020, 03:44 PM

My truck has the stock tach option but it was always way off. Then I put an HEI type distrib. in there and the tach just jumps around. Even the hand held multi-meter/tach that i tried hooking up just jumps around when connected to the tach terminal.

So my question is what after-market tach will fit in there and actually work with an HEI (Skip White or similar). I guess I'd have to remove the numbers from the lens.

Second question; is that old original tach repairable (can it be re-calibrated) and can it be made to work with HEI with some sort of inline adapter? Thanks -BA

**LockDoc** · 01-08-2020, 08:58 PM

Quote:

Originally Posted by WorkinLonghorn

My truck has the stock tach option but it was always way off. Then I put an HEI type distrib. in there and the tach just jumps around. Even the hand held multi-meter/tach that i tried hooking up just jumps around when connected to the tach terminal.

So my question is what after-market tach will fit in there and actually work with an HEI (Skip White or similar). I guess I'd have to remove the numbers from the lens.

Second question; is that old original tach repairable (can it be re-calibrated) and can it be made to work with HEI with some sort of inline adapter? Thanks -BA

I have read that an aftermarket ignition module can make some tachs read wrong or not be stable. I have also read that some setups require a resistor in the circuit for them to read correctly. I can't remember if they were talking about stock tachs or aftermarket though. There are threads on both problems.

LockDoc

**HO455** · 01-08-2020, 10:43 PM

Drop a PM to TBone1964. He is the resident expert and will have the answers you are looking for.

01-08-2020, 03:44 PM	#1
WorkinLonghorn Senior Member Join Date: Dec 2006 Location: Studio City, Calif. Posts: 2,861	Tach Question My truck has the stock tach option but it was always way off. Then I put an HEI type distrib. in there and the tach just jumps around. Even the hand held multi-meter/tach that i tried hooking up just jumps around when connected to the tach terminal. So my question is what after-market tach will fit in there and actually work with an HEI (Skip White or similar). I guess I'd have to remove the numbers from the lens. Second question; is that old original tach repairable (can it be re-calibrated) and can it be made to work with HEI with some sort of inline adapter? Thanks -BA __________________ '69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, 2nd owner, Work-Truck supreme. Best $300 I ever spent.

01-08-2020, 10:43 PM	#3
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 10,983	Re: Tach Question Drop a PM to TBone1964. He is the resident expert and will have the answers you are looking for. __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377



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