The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post

Pampas56 · 09-02-2012, 07:23 PM

I think that the timing mark was moved to behind the water pump on engines equipped with the A.I.R. system pump. The late 70's Targetmaster that I just bought had the timing mark low on the driver's side of the motor, which would be completely hidden by the power steering pump.

IIRC the P/S pump used to sit low on the passenger side and the driver's side was open. When the air pump was added the P/S pump was moved to the other side so the timing mark needed to be relocated. Not a big deal to swap timing covers and vibration dampeners.

I would be curious if anyone knows what the tube to the right of the timing marks is for. Maybe some weird motor application that required 9 degrees ATDC?

09-02-2012, 07:23 PM	#6
Pampas56 Registered User Join Date: Jul 2012 Location: Concrete, wa Posts: 77	Re: ignition timing 1980 gmc I think that the timing mark was moved to behind the water pump on engines equipped with the A.I.R. system pump. The late 70's Targetmaster that I just bought had the timing mark low on the driver's side of the motor, which would be completely hidden by the power steering pump. IIRC the P/S pump used to sit low on the passenger side and the driver's side was open. When the air pump was added the P/S pump was moved to the other side so the timing mark needed to be relocated. Not a big deal to swap timing covers and vibration dampeners. I would be curious if anyone knows what the tube to the right of the timing marks is for. Maybe some weird motor application that required 9 degrees ATDC?