The Stovebolt Site Forums The Shop Area Engine Shop Carb problems

1952 GMC 228 six cylinder. HEI ignition, a PCV system and Carter 964S carburetor, otherwise stock. The Carter carb was on the truck when I bought it 13 years ago. I rebuilt it once about 5 years ago, using a kit from Mike's Carburetor Parts (sorry Jon) to correct a seeping problem and played around with jetting sizes using an AFR sensor, but ended up back at the 0.099" jet that was in the carb when I got it.

Lately I've only been doing short trips and hadn't been keeping track of gas mileage, which is normally in the 13.5 to 14.5 MPG range. A few nights ago I loaded the trash can in the back for the 600' trip to the road. I left the engine running with the choke off, set the parking brake, turned on the bed/backup lights and got out to unload the garbage can.

There was no wind blowing. The smell of raw gas was coming from the exhaust pipe, really thick. The exhaust fumes were very visible in the beam of the lights. The idle was rough, hunting up and down by 100 RPM or so.

I filled the gas tank drove it to town and back twice over two days. Gas mileage was about 8 MPG.

I looked down the carb throat while the engine was idling. No "liquid" visible.

I adjusted the idle mixture screw all the way closed and it made no difference in idle quality, still real bad. So something is leaking somewhere, probably below the throttle plate.

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So for right now, I have removed the Carter carb and replaced it with a Zenith 28. My 228 would have left the factory with a Zenith 28, but the GMC Master Parts Book does not show this particular carb, which has a tag numbered 10163C.


Jon (CarbKing): Are you interested in looking at the Carter?