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GMC V6 and V12 Engines Engine repair and rebuilding

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Old January 14th, 2022, 07:17 AM
Prowbar Prowbar is offline
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Default Re: The fuel efficient GMC V6

Originally Posted by Quigley View Post
When I still had the 305D in my 62 1500 with 318 three speed and .456 rear gears I got 15 mpg on trips averaging 60 mph, couldn’t hardly believe it but it did. Now I have a 401 magnum with a 650 Edelbrock EVS2 and a 319OD trans and am getting 12 on trips. Pipes are pretty black and I think it’s a little rich. I put a bung in the exhaust and acquired a air fuel ratio device ,but have to wait till spring and the salt is off the roads to try. Has anyone tried this approach or tried fuel injection. Dave
I've heard of one guy using a throttle body on a 305 V6 but he only posted one picture.
http://67-72chevytrucks.com/vboard/s...d.php?t=486316 Posts 15 and 17 is about the TBI.

Most EFI is just a glorified TBI unit. This is great when the intake manifold does its job of feeding an even air/gas mixture to all cylinders. But I'm not sure it actually does. Difficult to find out other than running the engine with an O2 sensor in each exhaust outlet to find the A/F ratio of each cylinder.

An air-fuel ratio gauge is definitely invaluable when tuning the carburetor. I'd be interested in your finds!
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