Inliners International Forums General Discussion Engines Carburetor Help

Hi,

I have a 1967 Chevy C20 pickup that needed a new engine. With the help of 12bolt.com aka 12bolt tom. I got from him a still factory crated 194 block with pistons rings and cam bearings installed. So I built this engine for my truck. Using an adaptor I rebuilt a holly 4412 2 barrel carb for the engine. I used a good rebuild kit off Sumit Racing. The carb came off a V8 bus and my new engine hits huge flat spots and low power.

My question is can this type of carb problem be fixed by rejetting the carb to smaller jets and a say 7.5 power valve. I have no idea what jet sizes to use or power valve. Or am I out of luck and this is just to big of a carb. I pull around 15inhg for vacuum. I tried changing my timing advace and it does not help.
If I can fix this with jets and power valve what would be a good size? Also if this is to much of a carb what would be a good carb choice for this engine.
I'm not looking for a hot rod just drivable. I don't want to use the stock carb as they always leak out the lower shaft.

Thanks for any help on this, Chad

Off the top of my head...with a 194 running at 5000 RPM you shouldn't need more than 200-250 CFM?! So I suspect you might have too much carb??

Yeah, that Holley is 500 cfm, for the 194 you want something 180-225.
No way to make the Holley work on your engine by re-jeting.

Frank

The large throttle discs don't have fast enough air flowing through the venturis to activate the circuits, no way to fix it.