[gonec0untry]

I'm wrapping up the SS dash conversion and have everything working except for the Tach. I have all the proper grounds in place and I even added another from the gauge housing to the frame hoping that would make the Tach work. No such luck.

Tach:
I've tested the signal coming from the Tach and it's getting to the gauges. I tested the two posts on the CBP and it's getting power. I am really stumped on this Tach, I'm hoping I don't have to pull the dash. Is there a way to test the Tach??

Oil light:
When I ground out the oil sender the oil does light up so I know it's not the bulb. I have the bell type oil sender. 15 Yrs ago when I first bought the car I put in some aftermarket Sun Pro gauges that had the oil, temp, and vold meter. I re-hooked up the oil pressure, and it doesn't seem to work now either. Would the blue wire from the engine harness being reconnected keep the sun pro gauge from working?? I've attached a pic. The blue wire is the original wire reconnected, and the black wire is the wire that was used for the sun pro gauges. That's the wire that is used to ground out the sender to make the bulb light up. During the install it's just been laying unconnected on the floor board of the car. Any advice please?!?

 

[gonec0untry]

Do I have the right sending unit?!?? anybody?!?

 

[chevygod]

I believe the bell type sender is wrong. get a sender for a regular Malibu or Monte Carlo. I had my buddy at Chevy sourced all of the senders for me when I first rebuilt my motor in 84, he asked me if I had gages (I did) and gave me the bell type, which didn't work right.

On the tach, there is a circuit board inside the factory ones that sometime go bad. I used to sacrifice Camaro rallypacs to fix Chevelle/Monte gages. Also, I used to find that the coil that drives the needle (behind the gage face) would sometimes get bits of stuff magnetically stuck in it. I would use a pipe cleaner and get the junk out and the tach would work smoother.

ALso, are you sure your printed circuit is OK and continuous in all traces?

Tom

 

[gonec0untry]

I believe the bell type sender is wrong. get a sender for a regular Malibu or Monte Carlo. I had my buddy at Chevy sourced all of the senders for me when I first rebuilt my motor in 84, he asked me if I had gages (I did) and gave me the bell type, which didn't work right.

On the tach, there is a circuit board inside the factory ones that sometime go bad. I used to sacrifice Camaro rallypacs to fix Chevelle/Monte gages. Also, I used to find that the coil that drives the needle (behind the gage face) would sometimes get bits of stuff magnetically stuck in it. I would use a pipe cleaner and get the junk out and the tach would work smoother.

ALso, are you sure your printed circuit is OK and continuous in all traces?

Tom

Everything was brand new reproduction gauges and circuit board. I tightened all the nuts on the circuit board before the install. everything else works perfect. I tested the nuts on the back of the gauges and it's getting power.

Is there a second circuit board inside the Tach itself??

When the engine is running the tach goes from about 800 rpm to zero when I give it throttle in park.

Yeah, I'm thinking I have the wrong type of sender, too. This is what year one lists for all 70-72. Does this look right to you?

http://www.yearone.com/serverfiles/...&hid=012AA47883&cat=0&trk=12&searchid=5188395

 

[chevygod]

yes, there is a second board inside a factory setup, not sure on repro. double check the harness plug, make sure connections there are clean, especially from the coil to the tach. Are you using the original harness?

that looks like the sender I use on my gage equipped cars.

 

[gonec0untry]

yes, there is a second board inside a factory setup, not sure on repro. double check the harness plug, make sure connections there are clean, especially from the coil to the tach. Are you using the original harness?

that looks like the sender I use on my gage equipped cars.

New gauges and new wiring harness. everything else works correctly. I ordered a Tach filter that I've read is needed with the HEI distributors. I'll try that first. If that doesn't work, I guess I'm pulling the dash to take a closer look at the inside of the Tach. I've tested the signal coming into the plug for the gauges and it's getting power. I tested the terminals at the gauge, and it's getting power.

 

[chevygod]

never run a filter on my old cars with HEI. is this needed with the repro stuff?

can you hook a test tach up to the wire coming into the dash (I know it will be a pain in the ...) and verify that the tach wire is sending a good signal to the gage connector and therefore the tach? Also, check the traces on the flexible board and make sure all are intact and not broken. Even tho it's new, stuff happens.

Where in California are you?

 

[gonec0untry]

never run a filter on my old cars with HEI. is this needed with the repro stuff?

can you hook a test tach up to the wire coming into the dash (I know it will be a pain in the ...) and verify that the tach wire is sending a good signal to the gage connector and therefore the tach? Also, check the traces on the flexible board and make sure all are intact and not broken. Even tho it's new, stuff happens.

Where in California are you?

All the traces are good. Power is getting to the two terminals on the back of the tach. I'll have to pull out my old tach I had in the malibu dash where the clock was. It worked fine before.

 

[gonec0untry]

This might sound like a stupid question, but do I have to drain the oil to change out the oil pressure sender?!?

 

[sparky1698]

This might sound like a stupid question, but do I have to drain the oil to change out the oil pressure sender?!?

:noway:

 

[gonec0untry]

:noway:

does that shake of the head emoticon mean I don't have to drain the oil?!? lol Orrrr is it a shake of the head that you can't believe i don't know that. lol

 

[robo3]

dont have to drain it but i would put something under because youll get a little oil dribble out

 

[gonec0untry]

Thanks!!

On a different note: I've read that some people put a Y in the line for an external oil pressure while using the same "original" style sender. (not the style I currently have) Is that true? Will the original sender run both a gauge AND the oil light in the Tach, or is it a one or the other thing??

 

[chevygod]

the idiot light sender will only run a light, the bell-type gage sender only a gage. you can run both senders with a "Y" at the block and have a light and gage in the cart if you wish.

 

[gonec0untry]

Ohhhhhhhhhhhhhh!! That's what Y they were referring to and said to go to the plumbing dept. haha!! Thanks!! that cleared up that confusion!!

 

[chevygod]

Actually, you will probably find better brass "Y" parts at an industrial hardware store (like McFadden-Dale's here in Corona and elsewhere in SoCal), a genuine old school autoparts store, or at McMaster Carr catalog/online ( http://www.mcmaster.com/ ).

Look for "industrial hardware" on line for your area and see what comes up.

 

[1971ss454Elco]

Maybe I missed it earlier but did u say whether or not the tach was a GM unit or repro? If it is a repro unit-chances are good its circut board is fried! Repro units cant always handle the "signal" coming directly from the HEI because they are all NOT created equal.Th "filter" of which you and others speak of I used and did not help in my case.
I did the same thing u did and and was running a HEI and an MSD box. Well after endless hours of talking to MSD, the company who makes those repro tachs and testing of electrical system. yup the tach was fried.

MSD told me that they are not responsible for anything and the company that made/sold the tach to the guy I bought it from said they will not warranty it either as I used an MSD box and an HEI....... NOW that being said and after some research on my own I have concluded this in MY CASE ONLY.....

-MSD boxes are not needed in street apps NOR could I feel a "seat of the pants difference" with or without one plus the new "ready to run" dizzy from MSD I run does not need a box so I removed it.
-Original GM tachs were a lot better made than repro ones(DUH), can recieve and read the "signal" coming from HEI, MSD boxes and will generally hold up to them. Hence other peoples stories of having no problems at all when doing what u and I tried to do. You will also hear stories from folks that have no problems at all using repro tachs and doing what we tried to do as well-I say great, I wish I had been as lucky as them.
-Repro tachs are garbage plain and simple and arnt worth the $180+ dollars you pay for them-you are better off IMO to hunt down a GM one and pay big bucks to restore it IF you insisit on using an HEI and maybe the use of an MSD box.
-REMEMBER, regardless of who you buy repro parts from or any parts for that matter, they WILL NOT warranty electrical parts especially if they find out you are using an MSD box or an HEI dizzy.
-I dumped my HEI and MSD box, bought the afore mentioned MSD dizzy(which I got a black cap for) put in a second repro tach because the gentlemean I bought the first tach from knew what good business is and sold a second one below his cost. I have had NO issues at all in the last couple of years with this new set up. Fires first time every time, no fouling of plugs and runs great and clean.

Marc S

 

[gonec0untry]

Maybe I missed it earlier but did u say whether or not the tach was a GM unit or repro? If it is a repro unit-chances are good its circut board is fried! Repro units cant always handle the "signal" coming directly from the HEI because they are all NOT created equal.Th "filter" of which you and others speak of I used and did not help in my case.
I did the same thing u did and and was running a HEI and an MSD box. Well after endless hours of talking to MSD, the company who makes those repro tachs and testing of electrical system. yup the tach was fried.

MSD told me that they are not responsible for anything and the company that made/sold the tach to the guy I bought it from said they will not warranty it either as I used an MSD box and an HEI....... NOW that being said and after some research on my own I have concluded this in MY CASE ONLY.....

-MSD boxes are not needed in street apps NOR could I feel a "seat of the pants difference" with or without one plus the new "ready to run" dizzy from MSD I run does not need a box so I removed it.
-Original GM tachs were a lot better made than repro ones(DUH), can recieve and read the "signal" coming from HEI, MSD boxes and will generally hold up to them. Hence other peoples stories of having no problems at all when doing what u and I tried to do. You will also hear stories from folks that have no problems at all using repro tachs and doing what we tried to do as well-I say great, I wish I had been as lucky as them.
-Repro tachs are garbage plain and simple and arnt worth the $180+ dollars you pay for them-you are better off IMO to hunt down a GM one and pay big bucks to restore it IF you insisit on using an HEI and maybe the use of an MSD box.
-REMEMBER, regardless of who you buy repro parts from or any parts for that matter, they WILL NOT warranty electrical parts especially if they find out you are using an MSD box or an HEI dizzy.
-I dumped my HEI and MSD box, bought the afore mentioned MSD dizzy(which I got a black cap for) put in a second repro tach because the gentlemean I bought the first tach from knew what good business is and sold a second one below his cost. I have had NO issues at all in the last couple of years with this new set up. Fires first time every time, no fouling of plugs and runs great and clean.

Marc S

Hi Marc!

Thank you very much for your response. :beers: I've contacted the tachman, and he has an OEM Tach I can get from him. He's going to call me later today and tell me how much. EEk!!

 

[1971ss454Elco]

Hi Marc!

Thank you very much for your response. :beers: I've contacted the tachman, and he has an OEM Tach I can get from him. He's going to call me later today and tell me how much. EEk!!

That OEM tach SHOULD work just fine and live a long life if you are still using an HEI. However, I would also consider getting a second opinion here on this board and/or elsewhere on using that MSD "filter" we spoke of earlier. I have recently spoke with folks who said its a good insurance policy to use on even an OEM tach. It(the filter) just needs to be hooked up correctly is all.

Marc S

 

[gonec0untry]

That OEM tach SHOULD work just fine and live a long life if you are still using an HEI. However, I would also consider getting a second opinion here on this board and/or elsewhere on using that MSD "filter" we spoke of earlier. I have recently spoke with folks who said its a good insurance policy to use on even an OEM tach. It(the filter) just needs to be hooked up correctly is all.

Marc S

From reading I forums the filter from any GM late 70's and 80's Tach filter will work. I've ordered one off ebay. Should do the trick!! I know a local guy that has 10-15 chevelles and he's never had a problem with the OEM tachs plugged right into the HEI dist. He didn't even know what filter I was referring to when I talked to him. I"m still going to connect the filter to the HEI anyway. Like you said, for insurance. :yes: