67-72 factory tach adjustment - The 1947 - Present Chevrolet & GMC Truck Message Board Network

SERE · 10-25-2004, 06:57 PM

I posted a question on engine & drivetrain. Does anyone know how to adjust a 67-72 factory tach? I have got one that has a 3200 limiter of some sort on it. It just stops a 3200 RPM. The pictures are the dial on the back and I can't find anything in the manuals. Please help.

JimKshortstep4x4 · 10-25-2004, 07:28 PM

The adjustment on the back is for calibrating the RPM's against a known reference. I don't believe that it will help your problem. I suspect that you have a sticking needle problem. It is possibly rubbing against the face or part of the mechanism.

Jim

SERE · 10-25-2004, 09:37 PM

Thanks, What are the increments on the dial? Clicks or turns = ???RPM
If you know. I can always go trial by error.

Thanks again, Steve

Rod · 10-26-2004, 08:36 AM

I think its just getting stuck also.....I have ahad a few that do that....usually just a bit of taking apart and cleaning, it should work.

ckhd · 10-26-2004, 07:58 PM

If I remember right, there are no 'increments'. I hooked up a Sun tach up with the factory and had to fiddle with the adjustment for about 10 minutes before it read the same as the Sun. I would adjust it at, oh, 3000 rpm, then when I dropped it back to idle, it wouldn't match & vice versa. I don't know if it was dirty contact points in the adjuster or what, but it finally lined out and is very accurate.

SERE · 10-26-2004, 10:42 PM

Thanks, I wil let you know how it works out.

10-25-2004, 06:57 PM	#1
SERE "AIRBORNE" Join Date: Oct 2004 Location: Spokane WA Posts: 60	67-72 factory tach adjustment I posted a question on engine & drivetrain. Does anyone know how to adjust a 67-72 factory tach? I have got one that has a 3200 limiter of some sort on it. It just stops a 3200 RPM. The pictures are the dial on the back and I can't find anything in the manuals. Please help. Attached Images __________________ 69 GMC 2500 4X4 long stepside 454 BB

10-25-2004, 09:37 PM	#3
SERE "AIRBORNE" Join Date: Oct 2004 Location: Spokane WA Posts: 60	Thanks, What are the increments on the dial? Clicks or turns = ???RPM If you know. I can always go trial by error. Thanks again, Steve __________________ 69 GMC 2500 4X4 long stepside 454 BB

10-26-2004, 08:36 AM	#4
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	I think its just getting stuck also.....I have ahad a few that do that....usually just a bit of taking apart and cleaning, it should work. __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

10-26-2004, 07:58 PM	#5
ckhd Registered User Join Date: Oct 2000 Location: St. Johns, Arizona Posts: 2,660	If I remember right, there are no 'increments'. I hooked up a Sun tach up with the factory and had to fiddle with the adjustment for about 10 minutes before it read the same as the Sun. I would adjust it at, oh, 3000 rpm, then when I dropped it back to idle, it wouldn't match & vice versa. I don't know if it was dirty contact points in the adjuster or what, but it finally lined out and is very accurate. __________________ my 2¢ - t.i.o.l.i. Bowen 1968 K20 fleet 1969 K10 swb fleet 1972 K10 Suburban 1972 C10 lwb step 1992 K1500 'burb 1995 K2500 'burb 1997 C1500 'burb 1999 K1500 2000 K1500 'burb Why do I own so many Suburbans?

10-26-2004, 10:42 PM	#6
SERE "AIRBORNE" Join Date: Oct 2004 Location: Spokane WA Posts: 60	Thanks, I wil let you know how it works out. __________________ 69 GMC 2500 4X4 long stepside 454 BB

10-25-2004, 07:28 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	The adjustment on the back is for calibrating the RPM's against a known reference. I don't believe that it will help your problem. I suspect that you have a sticking needle problem. It is possibly rubbing against the face or part of the mechanism. Jim



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