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Old 12-02-2012, 10:34 AM
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Originally Posted by greazyball View Post
I have encountered my first trouble with this summit four barrel.the power vlave or accelerator pump has failed..i think.I noticed the truck was running very rich and then my mileage dropped to 10-12mpg i was getting a good 15-18.Im looking for a rebuild kit but it appears that the rubber diaphrams are not part of the kit..dammit! years ago when you got a rebuild got EVERYTHING that was a 'moving part'. I dont want to rebuild the entire carburetor it only has 6 or 7 thousand miles on it.I was told that these summit carbs use 'Holley' parts.Is this true? And i also would like to jet down a hair if i could.
Replace the power valve w/a Holley part. A '65' is the 'go-to' size for mild engines, if you have a big cam you may need to go to a smaller number so the enrichment doesn't come in too soon. Details of the engine and vehicle will help here.

The accelerator pump won't make it run rich. As long as you're getting a good stream from the shooters at the hit of the throttle and you have a tiny bit of free play at WOT the accelerator pump adjustment is OK. It might need a bit of tuning if you're looking for the best possible mileage, though.

BTW, you can use Holley jets, too.
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