Inliners International Forums Thread Like Summary - 2bbl or 4bbl

Hi all, I posted this question recently on one of the truck boards with some good responses. Thought I'd ask for thoughts/ideas/opinions here as well while I mull this over:

The Suburban has a stock 292 except for an HEI distributor and a Rochester 2-bbl sitting on top of an Offenhauser manifold with a homemade adapter. The 2bbl was a huge improvement compared to the stock 1 bbl in terms of power and drivability. The carb is now prettty worn.

I'm deciding between rebuilding/replacing the 2 bbl vs a new small 4bbl carb (Holley 390, Edelbrock 500). My goal is driveability and MPG (weekend driver). Interested to hear thoughts and experiences with any of these options and why one option might be better than another. I keep going back and forth in my head about this...

I was going to use a 2g on my 292, even had an adapter made for my Aussie Speed intake, and then decided on a Sprint 250 Quadrajet. Had the sprint carb built at stage 1 to account for the 292 and the lumped head. If I do decide to use the 2g, I have that option.

I have a pretty much built 207 in my '53 Chevy pickup. I original built the engine in the late 70s. A couple of rear end ratios & 3 different transmissions. The best it ever ran was with a Rochester 2G. The best milage is with an Edelbrock 500 four bbl. Possibly a smaller 4 bbl (Holly 390) would be better. I have used every jet/ meter combo in the Edelbrock book and several that are not in it. For the 292 I have planned for my '68 flat bed I'm going with an early '90s GM TBI injection.

I can't say how it runs yet, just got the block and head back from the machine shop yesterday. I now have to take inventory of my parts to see if I have everything to assemble it. It's been such a long wait I forgot what I bought...lol...

That 292 is just begging for a Rochester Quadrajet calibrated for a Chevy 305 or an Olds 307 engine. It has tiny primary barrels with a 3-step venturi, and a secondary air valve that prevents overcarburetion when those huge secondary throttle plates open up. The "small" Q-Jet has a 750 CFM rating, yet there are no flat spots from idle to all the CFM the engine can flow. I ran a 460 cubic inch truck pull engine based on a MOPAR 440, running a QJ for a 455 Buick. It dynoed at 714 HP at 6500 RPM on one carb and aviation gasoline. The carb would let it wind to 7500 RPM or more, but the torque started dropping off at that speed.
Jerry

I did not mean that a 250 should take same carb as a 350. What I meant. 250/6=41.66 CU per cyl 350/8=43.75 CU