HEI Tach adapter for Sun Super Tach?

[JRC99]

Does anyone make a tach adapter to make it work correctly? The Camaro's is way off. I know MSD makes one that is supposed to be used with their Blaster ignition, but the Camaro doesn't have any ignition box or coil.

EDIT: This may belong in the Day Two section actually. My apologies if it is in the wrong section.

[njsteve]

I just ran into the same problem installing the Super Tach II into my Gramma's Firebird with an HEI. GM made an HEI "filter" for its cars starting in 1975 to 1989 but it is no longer available new but you can find them in any GM car that had an HEI and a factory tach.

I saw several late model Monte Carlo SS's over the weekend at a cruise night and they all them, screwed to the firewall behind the dsitributor. It looks like an RFI filter that goes on the coil, but this actually is in line as the lead from the distributer to the tachometer. Several companies make them. Here is the guy I just bought one from.

http://rodneydickman.com/catalog/product_info.php?cPath=56&products_id=265

I don't know what year your tach is but some very early ones won't function with modern electronic distributors.

[Lynn]

I ran a Sun II in my car back in the 70's with a GM hei distributor, and don't remember needing a filter. Surely, I would remember having to come up with a filter. I remember it clearly as the gauge cluster was not installed (had been vandalized) and the tach was my only instrumentation. I had a 3 x 5 note card with the different speeds and RPM so I would know about how fast I was going. It was dead on accurate at 3600 rpm, which with my 4.10 gear was 70 mph. Only put maybe 3000 miles on the car that way.

[JRC99]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: njsteve</div><div class="ubbcode-body">I just ran into the same problem installing the Super Tach II into my Gramma's Firebird with an HEI. GM made an HEI &quot;filter&quot; for its cars starting in 1975 to 1989 but it is no longer available new but you can find them in any GM car that had an HEI and a factory tach.

I saw several late model Monte Carlo SS's over the weekend at a cruise night and they all them, screwed to the firewall behind the dsitributor. It looks like an RFI filter that goes on the coil, but this actually is in line as the lead from the distributer to the tachometer. Several companies make them. Here is the guy I just bought one from.

http://rodneydickman.com/catalog/product_info.php?cPath=56&amp;products_id=265

I don't know what year your tach is but some very early ones won't function with modern electronic distributors.

</div></div>

I'll check that out. The tach &quot;works&quot; so to speak, the needle moves and the light works, it's just inaccurate.

[njsteve]

When I first installed the tach last week it was &quot;jerky&quot; and would ratchet up with the RPMs or stop and hold at a certain spot. Not a smooth movement. Over a few days of driving it seems to have smoothed out. The filter arrives in a day or two and I will update as to what if any improvement in accuracy occurs.

[Lynn]

Would be good to know. May need to put one on the El Camino, and it has HEI.

[njsteve]

I received the tach filter today and installed it. It turns out that I did not need one since the tach worked before the install but not once the filter was installed. So I removed the filter and hooked the wires back up as before and it works OK again. I guess I just had a lazy tach to begin with. It seems to be working more accuratley as the days go by. So if anyone needs a filter for an early tach that is not currently working on an electronic ignition, I have the non-OEM looking version (that you can hide) that I will sell you for what I paid for it ($22 plus shipping).

[SuperNovaSS]

Sun Super Tachs have always worked for me off the HEI tach output. I think it is the 80's GM tachs that require the filter.


Jason