[79 Phoenix]

Hi. Does anyone know if a mid to late 70's Firebird tach would "bolt in" to a 74-77 Grand Prix guage cluster--replacing the clock?

74 Grand Prix cluster
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70-76?? Tach
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Also, are there any tachs from other models that fit a 74-77 Grand Prix cluster, replacing the clock? Thanks

[uforacing]

73-75 Grand am is the same.

[Ben M.]

Will it work? Yes. Will it fit into the hole without a lot of effort? No.

As said, '73-75 Grand Am and '73-77 Grand Prix clusters along with the '77 Lemans clusters with tach will all interchange.

[79 Phoenix]

Originally Posted by Ben M.

Will it work? Yes. Will it fit into the hole without a lot of effort? No.

As said, '73-75 Grand Am and '73-77 Grand Prix clusters along with the '77 Lemans clusters with tach will all interchange.

Okay, I hear you. This is uncharted territory for me and I'm trying to learn here. Given that there could be a lot of possible problems I would encounter, do you know any specific issues I would run into if I tried to do this?

[Ben M.]

Well if you have a non-tach car and want to convert it to a tach, at a minimum you need to recreate the tach harness.

I converted my '73 Grand Am to a tach and documented all of the steps involved here. Getting a factory tach is possible, the A-body guys are pretty close-knit and help each other out and some have stashes of these parts for not too expensive. The factory tach is a drop-in install to a clock cluster too as the one I had originally had a failed clock in it and it just bolted right in.

Now if you want to adapt a 2nd gen F-body tach cluster or '73-75 Lemans cluster, it will likely require drilling and cutting on the Grand Prix cluster to mount everything, and then you'll also need a hole drilled in the clear plastic for the clock adjustment lever (which is likely going to be in a slightly different place than a factory Grand Prix clock). Having a junk cluster to practice on might be a really good idea. And this also assumes that the depth of the F-body tach and clock assembly isn't too deep for the Grand Prix dash, there isn't much room to work back there for a non-factory application since it slides right into those 5 finger connectors and only has a narrow hole for the tach harness to slide in and out of.

My opinion? Just find a factory tach and install it. Takes less than an afternoon.

[79 Phoenix]

Originally Posted by Ben M.

Well if you have a non-tach car and want to convert it to a tach, at a minimum you need to recreate the tach harness.

I converted my '73 Grand Am to a tach and documented all of the steps involved here. Getting a factory tach is possible, the A-body guys are pretty close-knit and help each other out and some have stashes of these parts for not too expensive. The factory tach is a drop-in install to a clock cluster too as the one I had originally had a failed clock in it and it just bolted right in.

Now if you want to adapt a 2nd gen F-body tach cluster or '73-75 Lemans cluster, it will likely require drilling and cutting on the Grand Prix cluster to mount everything, and then you'll also need a hole drilled in the clear plastic for the clock adjustment lever (which is likely going to be in a slightly different place than a factory Grand Prix clock). Having a junk cluster to practice on might be a really good idea. And this also assumes that the depth of the F-body tach and clock assembly isn't too deep for the Grand Prix dash, there isn't much room to work back there for a non-factory application since it slides right into those 5 finger connectors and only has a narrow hole for the tach harness to slide in and out of.

My opinion? Just find a factory tach and install it. Takes less than an afternoon.

Thanks--I appreciate all this info! Gives me more to consider & think about. Question...I currently have an aftermarket tach in the car. Do you think there is any reason I couldn't connect a factory tach using the same connections--Ground, coil & battery? I realize I would need to find a factory plug for the factory tach or make my own connectors to the tach. I wouldn't want to short out a new tach.

Also, what I'm really trying to do is install a 74 Grand Prix gauge cluster in my 79 Phoenix. I bought a 74 GP cluster (on its way) guessing it will fit my Phoenix...but have not been able to verify as to whether this will even fit.There is very little info that I've been able to find about the Phoenix as not too many people bother with them. But I'm guessing the cluster will fit or can be made to fit without too much trouble...We'll see.(see pictures).

Also, regarding the rally gauges in the new cluster, assuming the plugs fit, do you think the sending units and warning light plugs in my current cluster will work with the rally gauges in the new cluster?

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[zeebo]

i did not know that the 79 phoenix (ventura) had the same cluster as the grand prix/grand ams! lol....and is that baby a 4 speed? not to hijack the thread.. i would think that it is possible to do this swap---as mentioned, get a factory correct tach and you can get a tach harness as well through certain suppliers repop. while you are at it, try and install the full gauge cluster and hook them up--that would make for one nice dash!

you will need sending units for the oil pressure and temp needle gauges to work correctly..but those can be sourced easily. just get a service manual and trace every wire going to the new cluster from the phoenix harness and make sure you dont have to reroute some in the pin connector. looks like your fuel gauge in the phoenix cluster is in the upper lh corner, so you should be good to go on the wiring!

[79 Phoenix]

Originally Posted by zeebo

i did not know that the 79 phoenix (ventura) had the same cluster as the grand prix/grand ams! lol....and is that baby a 4 speed? not to hijack the thread.. i would think that it is possible to do this swap---as mentioned, get a factory correct tach and you can get a tach harness as well through certain suppliers repop. while you are at it, try and install the full gauge cluster and hook them up--that would make for one nice dash!

you will need sending units for the oil pressure and temp needle gauges to work correctly..but those can be sourced easily. just get a service manual and trace every wire going to the new cluster from the phoenix harness and make sure you dont have to reroute some in the pin connector. looks like your fuel gauge in the phoenix cluster is in the upper lh corner, so you should be good to go on the wiring!

Thanks for the info! Yes it is a 4 speed! Originally it was a Chevy 305 with automatic but I converted it to 350 4 speed. I bought a GP cluster that has a clock and no tach.I've been having a hard time finding a factory tach for a reasonable price so I can swap out the clock for a tach.It would be great to have all the gauges in the dash!