[KGTO]

The 67 shop manual states there is a plug on the back of the tach to adjust it. Can this be done in the car and where the heck is it?! I have crammed my head behind the dash a few times and I can't find it. Is it a metal plug? How big is it and where is it?

Thanks

1967 GTO 400 4-speed (416) #62's 11:1 solid lifter 6.8 Eagle/Ross full exhaust 11.80's@116---> UPDATED, heads race ported (287/200) and extras; shooting at low 11's in the spring, 10's on spray!

[KGTO]

The 67 shop manual states there is a plug on the back of the tach to adjust it. Can this be done in the car and where the heck is it?! I have crammed my head behind the dash a few times and I can't find it. Is it a metal plug? How big is it and where is it?

Thanks

1967 GTO 400 4-speed (416) #62's 11:1 solid lifter 6.8 Eagle/Ross full exhaust 11.80's@116---> UPDATED, heads race ported (287/200) and extras; shooting at low 11's in the spring, 10's on spray!

[george kujanski]

There should be approx a 1/2 inch hole in the rear of the housing with the adj potentiometer visible thru the hole. Good luck on being able to see the thing from under the dash..if you are a contortionist and have a mirror to use it may be possible.

Regards, George

[KGTO]

Thanks George,
What kind of tool is used, a small flat blade screwdriver?

1967 GTO 400 4-speed (416) #62's 11:1 solid lifter 6.8 Eagle/Ross full exhaust 11.80's@116---> UPDATED, heads race ported (287/200) and extras; shooting at low 11's in the spring!

[george kujanski]

Yep, a blade about 1/8" wide, if I recall correctly.

Regards, George

[Peter Serio]

This is a classic case of the people who wrote the shop manual did not know that the hole in the rear of ALL of the 65 thru 67 at least, rally gauges tachometer were deleted in 1965. (The 64 has a hole, with a little yellow piece of clear tape over it.) There is NO HOLE in any 65, 66 or 67 tachs, the only way to adjust the tach's final trim for those 3 years is to remove the dash from the car & remove the tach from the rally cluster. Not an easy feat for an afternoon's worth or work. Most tachs now are so far off &/or need rebuilt anyway, that turning that little screw really does nothing anyway, it's only for the final "tweak" on a brand new tachometer during the warranty period, ONLY!! Or at least that's what it was intended to be used for if the hole had been there in the first place.
If you try & drill your own hole now you will most likely ruin your tach as the circuit board is only 1/8" behind the metal where you would be drilling plus the Tachometer's meter movement will magnetically attract the metal chips, thereby jamming up the meter & it will stick from then on at 2 or 3,000RPM.

Peter Serio
Owner, Precision Pontiac

[george kujanski]

Peter, I'm afraid you are right. Just checked my '67, the hole I remember is for the light; can't get to the potentiometer thru the hole. I remember a pot inside, just can't get to it externally. Have to pull it out to adjust it.

Regards, George