Inliners International
Posted By: Chevelle292Wagon 1 barrel on 4 barrel Offy Intake - 06/27/20 10:38 PM
Hi,
It sure has been quiet on the forums.

I've been thinking about what carb to use on a Chevy 250.
It was in a 64 Chevelle with Turbo 350, 390 Holley, Clifford manifold, headers, hotter cam, head work.
Going into a resto mod car, a 64 Malibu SS.
This car had a 194 w/ Powerglide.
Now going to be a 250 with 4 speed. Trying to make it look stock.

I want to run the big 292 sized 1 bbl Rochester B model on a Offy 4 bbl intake with a stock exhaust. (Offy will be painted orange to fool most of the people some of the time)
Thinking I could carve out the part of intake with the 4 holes and then make a custom plate to bolt the 1B onto and be able to swap to a 2 or 4 barrel later if it seemed like a better idea.

Q. I don't think the structure of the manifold should be compromised by the metal removal. Am I right?

Q. 1/2" or 1" for mounting plate?

Be interested in members thoughts.
Thanks
Posted By: Twisted6 Re: 1 barrel on 4 barrel Offy Intake - 06/28/20 07:16 PM
No it will not hurt the intake any by removing the 4port web. As for the carb plate No less then a 5/8 plate so the linkage should clear the intake. Just put the stock 4b plate aside for a later date. If your offey came with one.
But why not just stay with the stock intake? If your going to use
the 1b carb.
Posted By: Rjonah Re: 1 barrel on 4 barrel Offy Intake - 06/29/20 01:56 AM
+1 on what Larry wrote.

The Offy and stock are very similar in plenum and runner design. Why not use the 1 barrel manifold for what it was designed for and when you need more juice, break the Offy back out and use it what it was designed.

If it will work in the engine bay, get the larger exhaust manifold from a 292 and get a little better breathing on the exhaust side. The 292s flange is bigger but note, the flange is 3 studs vs the 2 of the 250.

Regards,
Rick
Well the idea is, yeah the Offy is close to the stock iron intake in design but it is aluminum so should dissipate heat better.
Also if the big B or BV Rochester misbehaves I can switch to the 283 2 bbl I have without taking it all apart again, just swap plates.
I do have a newer 2 1/2 " exhaust manifold but was saving it for a 292.
The adapter is probably going to be thicker than I imagined to allow for linkage, which I forgot about so thanks for pointing that out.
No auto kick down to allow for so that helps.
Might have to look at a 2 to 1 bbl adapter in reverse.
I know the Rochester B has few fans around here but if I can take care of the hiccups pointed out over the years it should work.
I have 2x1 and 3x1 Offy intakes also, but I'll save them for down the road. Then I might have to go with the little Holley-Weber 2bbls.
Thanks
Originally Posted By: Chevelle292Wagon
Well the idea is, yeah the Offy is close to the stock iron intake in design but it is aluminum so should dissipate heat better.


The aluminum intake will also ABSORB heat more readily, leading to fuel control issues like vapor lock. I have experienced this on an O/T V8 leading me to have to block off the heat riser, install a fuel return line, etc.
Posted By: Twisted6 Re: 1 barrel on 4 barrel Offy Intake - 06/29/20 06:11 PM
chevelle292wagon I sent you a PM. If you weld up the plugs on the bottom of the offey you can add heat. If your not using the stock exhaust like it was meant to use.
Ok, thanks for comments, I have to think this out somemore.
I have stuff laying around, I'll have to see what looks like it will work best. Not a max horsepower effort starting out, but who knows- might just end up throwing on the 4 barrel and headers.
Don't think I'll be able to fool anyone into thinking it came like that! : )
© Inliners International Bulletin Board