Inliners International Forums General Discussion Engines 302 with Multiple Zenith Carbs

Good Evening All,
So I'm planning out my next build and venturing into new territory (I've been a very stock builder in the past). I have a '54 civilian 302 block and head (flat pistons) and I'm looking to use a McGurk intake with either 2 or 3 single barrel, zeniths. I have 2 rebuilt BV10s (originally off of 228 GMCs) ready to go and possibly looking for another. Obviously, a single BV10 wouldn't be nearly enough carb for a 302, but would 2 work? Would 3 be better? Or should I start looking for larger zeniths like BV11s for 12s? I hope I've included enough info in this post, but if not, I will gladly elaborate.
Thank You All,
Deltamac

A lot still depends on how radical the engine will be. How big of a cam...? How high of an RPM will it operate in...etc? There are numerous carb CFM calculators based on some of these parameters. Most multi carb setups were purely for looks and less for functionality, so only select what the engine truly needs....

There is a performance gain with a proper multiple carb set up. It won't compare with port injection but that doesn't matter to most of us. The most carbs I ever ran was a 3 side draft setup from a '54 Vette on a 261 in a '40 Chevy pickup. The engine was not a race build but pretty strong. If there had been 1/8 mile drags back then I would have been famous. I've run several 2x1 setups and one 2x2. They all ran better than a single 1 bbl carb. I had a 2-jet on a 270 that ran very well. The coolest looking is a 3X2 Harper, and probably the most complicated.

I have always liked Zenith 28-228 with the adjustable main jets. They worked for me and are very adjustable. They have replaceable different size venturies if you can find them. I had a pair built a while bace for a 153 Chevy 4 cylinder I'm building for a roadster. They came on a lot if GMCs & International trucks. As for size you just have to do your homework and remember that most modern carbs are calibrated for V8s. Oh, The 270 I'm running now has an Edlebrock 4 bbl. It works but no cool factor.

I used to run a 302 GMC with three Weber 32/36 carbs in my 40 Chevy coupe. The manifold was home made. I still have it as wall art in my garage. I tried to make it look like the classic Harper manifold. The three intakes were made from 90 degree mandrel bends. The bends tapered the flow down from the Weber 2 barrels into the single round GMC intake ports. My first design use 1/2 inch I.D. rubber hose between the the three tapered intakes . It ran quite well. I could really feel the car pickup when the larger barrels kicked in. But I could not leave the design lone. I decided to replace the rubber hose balance pipes with 1 inch steel tubing. I lost the acceleration kick when the Weber's larger barrels kicked in. I would go back to the smaller rubber hose balance tubes if switched back to the three Weber manifold. The big drawback to this design is the complexity. The number of pieces is roughly 3X what a single 4 barrel manifold would need.

I am now in the process of making my old Chevy easier to drive. I am trying use a 200R4 with overdrive and a Holley 395 cfm 4 barrel. The small Holley works well. I have not had much luck with the the 200R4. If anyone is thinking of a similar modification think about have a professional do the installation.