How to add a tach to non tach cluster??

[NorCalC20LWB]

Have a 72 that at some point was upgraded to HEI. Want to add a tach and Brothers Truck Parts has an upgrade kit on sale right now, but they said it will not work with an HEI system. Any suggestions??

[Mike (Asheville)]

Originally Posted by NorCalC20LWB

Have a 72 that at some point was upgraded to HEI. Want to add a tach and Brothers Truck Parts has an upgrade kit on sale right now, but they said it will not work with an HEI system. Any suggestions??

My 72 has GM HEI and I bought that tach upgrade kit from Brothers and couldn't be happier. They included a bezel for an 8k rpm tach which confused me at first, but they were quick to send out a replacement for the regular 5k. Not sure why someone told you it won't work, because it definitely does. And $199 is a great price.

There's a pic showing the tach with my engine running here: http://67-72chevytrucks.com/vboard/s...16#post8061316

[HIGHWAY BY THE SEA]

I also have an HEI with tach in my 68, and it works perfectly. Not sure where the PO bought the tach though. It was in a cluster I bought, and I doubt it is original.

[NorCalC20LWB]

Thanks guys for the replies. The HEI distributor in mine as an MSD. I assume if it works with a stock GM setup it would work also with an MSD system? The biggest fear is that I somehow fry the new tach and am out $200.

[LH Lead-Foot]

You never know about the guy who answers the phone and says "Parts Department"!
After 30+ years in shops and dealers, I have come across few that know how systems work.
You are getting a quality reproduction tach designed to work with HEI. So, wire to HEI negative terminal, thru grommet, allow extra wire (Unless Included) and attach to the clusters terminal or directly to tach.
I am not familiar with the current offering from Brothers, but you get an 8 cylinder signal to an 8 cylinder tach. I will go and check anyways.

Only in the "LS" generation, the tach signal comes from the PCM and is programmed to produce a 4 cylinder signal. Those who do these swaps can have the PCM reprogrammed or change the switch setting on the back of the tach is so equipped.
Yours is plug and play. Turn the key, smile and go for a drive.

[718jwh]

Not sure what brand Brothers sells but if you go to Classic Parts.com they sell a tach conversion kit and it says it will not work with HEI. If it’s the same brand then that is a bummer because $200.00 is a good price.

[NorCalC20LWB]

Went ahead and ordered the tach, regularly $375 on sale for $200. Back ordered of course but for that price I'll wait. I have seen the tach conversion kit on the Classic Parts website, but you're right, they also say not for HEI. No idea why they all say that, seems plenty of folks run them just fine with an HEI system.

[Killer Bee]

interestingly, I have heard of this issue several times in the past however I don't see any reference to it in the brother's ad or their videos..

67-72 TACHOMETER CONVERSION SET - 5,000 RPM

this video does reference the 5k or 8k rpm range option for 'high performance' engines approx 0:30..

from that I would infer that electronic ignition would likely be used..

You Tube

You Tube

this tach / clock conversion kit doesn't reference the issue either..

67-72 TACHOMETER / CLOCK CONVERSION SET - 5,000 RPM

so after more searching, couple of older threads popped up..

Repro Tach and HEI

Tachometer Conversion Kit

etc..

good luck y'all!

[Mike (Asheville)]

Originally Posted by NorCalC20LWB

Went ahead and ordered the tach, regularly $375 on sale for $200. Back ordered of course but for that price I'll wait. I have seen the tach conversion kit on the Classic Parts website, but you're right, they also say not for HEI. No idea why they all say that, seems plenty of folks run them just fine with an HEI system.

It's a good kit and a great buy. The design of the indicator needle doesn't match my speedo and fuel gauge but it's not something the bothers me. I took advantage of the opportunity while transferring the instruments to clean them up, touch up the needles and upgrade to led instrument lighting. I also discovered a rat's nest of dodgy radio, a/c and trailer wiring and cleaned all that up.