The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Truck has started running rich & terrible MPG

rich weyand · 09-25-2016, 08:19 PM

Yup. Aftermarket tach should have 4. 6. 8 selector. If that's wrong....

As for timing, I assume you have a timing light. A cheap one will work. Like $20-30 at any auto parts store.

Disconnect the vacuum to the distributor. You can plug the hole, but you don't need to just to set the timing.

Measure your timing at idle. You are probably around 8* BTDC. You should be able to go up to 12-16* BTDC. More is better as long as it doesn't knock when you get on it at low speed going uphill. Make sure you clamp the distributor back down tight.

I assume in recommending this that you moved the vacuum advance line to the side port on the Qjet.

09-25-2016, 08:19 PM	#8
rich weyand Registered User Join Date: Apr 2014 Location: Bloomington Indiana Posts: 1,041	Re: Truck has started running rich & terrible MPG Yup. Aftermarket tach should have 4. 6. 8 selector. If that's wrong.... As for timing, I assume you have a timing light. A cheap one will work. Like $20-30 at any auto parts store. Disconnect the vacuum to the distributor. You can plug the hole, but you don't need to just to set the timing. Measure your timing at idle. You are probably around 8* BTDC. You should be able to go up to 12-16* BTDC. More is better as long as it doesn't knock when you get on it at low speed going uphill. Make sure you clamp the distributor back down tight. I assume in recommending this that you moved the vacuum advance line to the side port on the Qjet. __________________ Rich Weyand 1978 K10 RCSB DD.