I'm at the end of my patience. I have a Carter 750 cfm carb on a moderately built 454 fresh rebuild. It drinks gas at a ridiculous rate, and fouls plugs.

I have cleaned/rebuilt the carb 3 times, replaced plugs, and have no vaccum leaks. Also, I adjusted the float levels, and turned off the electric fuel pump, but still no change.

I'm pretty sure that the carb, is not modified in any way.

is it possible that 750 is just too big?

Nahh, not too big. I ran a 780 Holley dual-feed on a 327 in my '56 Bel Air. Of course, it had 12:1 TRW's and a solid lifter cam with a shift point of 8500RPM. But still ....

High float levels? Did you recheck the number you are setting them to? Too cold a plug maybe? How much compression per cylinder?

The factory carb on the LT-1 and 375hp 396 was a 780cfm Holley so a 750 should not even be close to too big on a 454.

Sure you don't have a jetting issue?

I have a Holley 750 on my tame 454 and it runs great. I got 16mpg on one highway tank. I'd look at jetting...

Or your foot...(don't we all)

Thanks for the sound advice. The 454 is a 10.25 to 1 compression ratio.

I've downloaded a good Carter owners manual with a nice exploded view.

That is mainly how I've educated myself so far.

I want to pursue the jetting issue, but I need to understand the terms as they are labled in the diagram because there are a couple of parts labled "Jets" in the diagram.

Are you refering to the part the metering rods (called "step-up rods" in the diagram) go in?

These are called "Primary metering jets" in the diagram.

By the way, my metering rods are labeled "7147".

I know this is a bit wordy, but none of the terms in the diagram match exactly so I want to make sure I understand all this.

You might also consider buying a wideband O2 sensor/monitor to see what your actual A/F ratio is. It's a handy item when tuning the fueling system.

speed demon 750 on my 454HO. runs great.

if you are running a dual plane, you could run an 850 or a 1000 and it still would not be too big. Something else is wrong, but dont expect to get 20mpg.....

Something else is wrong for sure. I would take a look at a 750 or 850 Holley classic like the 4779, nice carb, easy to tune and the price is good too

Yeah, what he said. The Carter isn't a carb to learn fuel curves, jetting, etc on. As Motorhead said, score a 750 Holley on ebay (be patient and you can find a good used one for $50-75) plus a rebuild kit ($28). Jet it according to the Holley charts for that model and you'll be in the ballpark. I have a 750 holley (4779) on my mild 454. LOVE IT! It's perfect!

I have a clean 750 Holley with vac secondary. Had it on mine and ran OK. Carb has been dry for 2 years, would have to have a kit. fuel line included.