I just ditched my old mopar ignition and installed a Summit cdi box (msd 6a copy ) and msd dist. Tach is a Autometer 5" .

Car runs nice but now my tach reads around 600 rpm too low . Tach is wired correctly to the gray tach wire from the box. Summit box is set to 8 cylinder

Someone mentioned I need a MSD tach adapter.................so is every car equipped with a MSD 6a and a Autometer tach running an adapter ??? Doesnt sound right....




https://www.summitracing.com/parts/sum-850620

With an MSD 6 & AutoMeter 5" I never ran an adapter.

Your not the first person to have accuracy problems with Auto Meter electric tachs using race ignitions
Call MSD

Yea..i will call msd and summit. I cant believe i would have to buy a $60 adapter to run this tach off a msd style cdi box ??

Thats why i asked......with thousands of race cars with Autometer 5" tachs and 6al boxes .....I believe this Summit box is made by Msd in Texas .

I just installed MSD 6AL digital unit on my car. I have an old Motoralla tach and it works fine hooked to the gray wire. No adapter at all needed with MSD on mine. Ron

I have a MSD 6 AL2 and the Autometer tach doesn't need an adapter but my factory rallye tach does. I run them both one off adapter on grey wire the autometer just off the gray wire.

4 cars in my stable all with MSD 6AL boxes. 3 cars have Autometer and 1 car has an AutoGage (Cheap version of Autometer) tach. No adapters needed on any of the cars.

For 600 rpm I think the tack needs a calibration.. I've owned a few and one 1 was off by about that much
just a guess

It worked perfect before i changed the box and dist. idle was around 1,100 before ....now its at 500 ish

Send that cockroach back to Autometer and have them fix it or replace it on their dime and time

i bought it used years ago......i wonder what they charge...i still havent been able to get Summit tech on the phone