Is Original tach compatible with HEI ?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ghackett1 · 11-03-2006, 08:50 PM

I just purchased the tach conversion set up for my 71 c-10 pick up. But the directions said the new repro tach is not compatible with an HEI distributor which my truck has (late 70,s gm style). Do I need to put a points distributor back in or what? Please let me know as I want to complete this project now that I have my new parts! Thank you.

Machu10 · 11-03-2006, 09:01 PM

i have a factory repop tach connected to my crate 454ho, it works like a charm.

crm318 · 11-03-2006, 09:32 PM

i have a repo tach in my 72 cheyenne with a 350 and hei. it works great and is just the look i was going for.

ghackett1 · 11-03-2006, 09:43 PM

Okay thanks for the help. When I purchased the kit I could not see why there would be a problem so I was surprised to see the quote that said "Will Not Work With Hei". I'm gonna hook it up this weekend. I'll update you on the progress. Thanks again.

Huck · 11-03-2006, 09:48 PM

the HEI system uses a different wave length of signal that the tach picks up. The original tach's were far from accurate running off the stock distributor and when hooked up to an HEI dist, they are off a bit more but--I too am running an aftermarket reproduction of the original on my 350 with HEI and have had no problems.

msgross · 11-03-2006, 10:05 PM

my original tach doesn't seem that bad with HEI. Maybe I should hook up an aftermarket to see the difference....

corn · 11-03-2006, 11:18 PM

I was told they do that so they can sell you their adaptor for another $100. All it is, is a piece of wire with the HEI plug on the end of it...

ghackett1 · 11-04-2006, 10:30 AM

Thanks again for the quick responses. I'm new to the site and just purchased a 71 custom deluxe Big Block original motor truck! Its my baby, as soon as I get some pics I'll post them. Thanks.

11-03-2006, 08:50 PM	#1
ghackett1 68 C10 Longbed Join Date: Sep 2006 Location: Naples, Florida Posts: 518	Is Original tach compatible with HEI ?? I just purchased the tach conversion set up for my 71 c-10 pick up. But the directions said the new repro tach is not compatible with an HEI distributor which my truck has (late 70,s gm style). Do I need to put a points distributor back in or what? Please let me know as I want to complete this project now that I have my new parts! Thank you.

11-03-2006, 09:01 PM	#2
Machu10 Junior Member Join Date: Oct 2006 Location: Central, Iowa Posts: 38	Re: Is Original tach compatible with HEI ?? i have a factory repop tach connected to my crate 454ho, it works like a charm. __________________ 72 Cheyenne Super ShortBox, Factory Big Block, A/C PS PB. 71 Cheyenne LWB, 350, A/C, 48k Miles 70 Olds Cutlass Convert, A/C, 350 auto, 66k actual miles. 82 Corvette, Triple Black, 32k Miles, Had since new. 85 Caprice Coupe, Bottle fed 383 Stroker, 30k miles. 06 Dodge Charger Daytona, Top Banana Hemi.

11-03-2006, 09:32 PM	#3
crm318 Alright Alright Alright Join Date: Mar 2004 Location: Midland, Texas Posts: 1,672	Re: Is Original tach compatible with HEI ?? i have a repo tach in my 72 cheyenne with a 350 and hei. it works great and is just the look i was going for. __________________ 1972 Cheyenne Chevrolet red and white 357ci, Vortec heads, GM Performance high rise intake, Comp 268H .454/.454 218/218 110 LSA Quadrajet carb, Flowtech headers, 2.25 40 series HEI, Curve kit, TH 350, 3.07 gears 275/60/15s on 15x8 rallies

11-03-2006, 09:43 PM	#4
ghackett1 68 C10 Longbed Join Date: Sep 2006 Location: Naples, Florida Posts: 518	Re: Is Original tach compatible with HEI ?? Okay thanks for the help. When I purchased the kit I could not see why there would be a problem so I was surprised to see the quote that said "Will Not Work With Hei". I'm gonna hook it up this weekend. I'll update you on the progress. Thanks again.

11-03-2006, 09:48 PM	#5
Huck Senior Member Join Date: Jun 2001 Location: Shelbyville, KY Posts: 3,269	Re: Is Original tach compatible with HEI ?? the HEI system uses a different wave length of signal that the tach picks up. The original tach's were far from accurate running off the stock distributor and when hooked up to an HEI dist, they are off a bit more but--I too am running an aftermarket reproduction of the original on my 350 with HEI and have had no problems.

11-03-2006, 10:05 PM	#6
msgross Registered User Join Date: Jul 2006 Location: Central PA Posts: 12,201	Re: Is Original tach compatible with HEI ?? my original tach doesn't seem that bad with HEI. Maybe I should hook up an aftermarket to see the difference....

11-03-2006, 11:18 PM	#7
corn Registered User Join Date: Dec 2003 Location: here Posts: 5,789	Re: Is Original tach compatible with HEI ?? I was told they do that so they can sell you their adaptor for another $100. All it is, is a piece of wire with the HEI plug on the end of it...

11-04-2006, 10:30 AM	#8
ghackett1 68 C10 Longbed Join Date: Sep 2006 Location: Naples, Florida Posts: 518	Re: Is Original tach compatible with HEI ?? Thanks again for the quick responses. I'm new to the site and just purchased a 71 custom deluxe Big Block original motor truck! Its my baby, as soon as I get some pics I'll post them. Thanks.



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