tach

[Snoots]

Ah, my bad

No worries. It's not yer bad. The tach was an option. That's why it's not wired in with the main cluster.
Is odd that they still offered it with an automatic tranny. May have been because of the 4WD.
What the heck do I know?

 

[daylight]

howdy the guages were of a blazer

 

[Rusty Nail]

I like this thread.

 

[Snoots]

I thought the tachs which took the place of the fuel gauge wired like a normal aftermarket tach and the small fuel gauge still plugged into the main board. Kind of like these. http://www.gmsports.com/content/new-tachometer-1973-1988-chevy-and-gmc-trucks

I haven't seen those. Looks like a very nice upgrade. The price seems about what you'd expect.

 

[Green79Scottsdale]

I thought the tachs which took the place of the fuel gauge wired like a normal aftermarket tach and the small fuel gauge still plugged into the main board.

That is how it works. When you go to a tach and use the stock gas gauge you need to get the appropriate printed circuit for the back of the cluster. This routes contacts to the gauge from the wiring harness so everything works.

 

[Dutch Rutter]

Ah gotcha. it would definitely look nice and clean up the aftermarket tachs that get zip tied to the steering columns, Such as mine.

 

[75gmck25]

Just make sure the cluster you are buying is a year that is compatible with your '78 truck.

For example, I used a '74 tach cluster in my '75, since they are identical designs. However, my cluster uses a mechanical oil pressure gauge and an ammeter, while a stock '78 cluster probably has an electric oil pressure gauge and a voltmeter. You could not swap my tach cluster into your truck without making some signficant wiring changes, and adding a hard line for the mechanical oil pressure gauge.

Bruce

 

[daylight]

howdy gauge cluster come off 81 blazer. the tach has own harness which i have to splice in tach-adpt to make it work for a 6 the gauges are electric. i do have to change the senders oil and water all i had was idiot lights

 

[Snoots]

Found this:

https://www.jalopyjournal.com/forum...attached-to-6-cylinder-engine-question.96494/


A little late to the party here on this subject, but I actually make a little converter box that allows you to use a 4, 6,
or 8 cylinder tach with a 4, 6 or 8 cylinder engine. Bob --- [email protected]

 

[Green79Scottsdale]

howdy gauge cluster come off 81 blazer. the tach has own harness which i have to splice in tach-adpt to make it work for a 6 the gauges are electric. i do have to change the senders oil and water all i had was idiot lights

Get yourself wiring diagrams for both your 78 and an 81 to compare them. You most likely will need to move some pins around in the plug that goes in the back of the cluster. The physical job of moving them is quite easy, but knowing where to move them to is another story.