Rochester 4jet 4GC capability

[67Nova421]

I know some of you probably run a Rochester 4jet or 4GC carb in certain classes. I'm wondering if this carb is capable of making some decent power? It's small...I know that. I have my doubts about it being able to support a 400ci SBC to 5500+rpm. I've heard they can make some power I just want to hear some real world experience and the draw backs of them. Thanks.

[Woodfin]

The small carbs run surprisingly well on a 283 or 327, especially to the 1/8 mark. But they are limited, and the same engine with a larger carb makes more power. A 400 would be greatly restricted.

[Mark Yacavone]

There are at least four different size 4GCs.
What are you working on?

[67Nova421]

Originally Posted by Mark Yacavone

There are at least four different size 4GCs.
What are you working on?

It's original off a 59 Vette. The primaries and secondaries are the same size so I'm thinking it's the smallest version? The reason I ask is I was trying to build an engine for the Vette that looked completely original and stock but it'll be a hopped up 400ci. 10:1 compression, ported 2.02 041X heads, 230ish cam @ .050. The 400 will probably make peak power about 5500rpm so if the carb can even get close to that I'd be happy. But if it's going to stall out at 4500rpm that's probably not going to be worth trying out.

I just finished a full rebuild lastnight


And here's a pic of the primaries and secondaries if that helps determine which carb it is

[Mark Yacavone]

The 59 is the smallest.
The 65/66 PP is a bit bigger.
What you want is a 340 hp 409 carb.
I don't think they had the filter up top , but that top you have will fit right on it. ;-)

[67Nova421]

Originally Posted by Mark Yacavone

The 59 is the smallest.
The 65/66 PP is a bit bigger.
What you want is a 340 hp 409 carb.
I don't think they had the filter up top , but that top you have will fit right on it. ;-)

Ok that's what I was afraid of. I have a nice 750 double pumper and a Victor JR I can paint the engine color and somewhat hide it all with a factory Corvette air cleaner. Is there a certain name for the 340hp 409 carb to search for it?

[pmrphil]

Getting a Victor Jr. to fit under the hood of a Vette may be a touch interesting

[67Nova421]

Originally Posted by pmrphil

Getting a Victor Jr. to fit under the hood of a Vette may be a touch interesting

Yeah good point. It seems like there's a lot of room under there on the 59 but maybe it's misleading. I've still got the block in the car I'll just sit some heads back on it and mock up everything see if that's going to work.

[Dwight Southerland]

Originally Posted by Mark Yacavone

What you want is a 340 hp 409 carb.
I don't think they had the filter up top , but that top you have will fit right on it. ;-)

Or a 63-65 Oldsmobile 394 carb or 63-65 Cadillac 390 carb

[Alan Roehrich]

You can actually find the 2x4 setup for the WCFB for the 265/283 on a fairly regular basis. They're not cheap. But they're not crazy expensive, either, especially if you don't care if it is a "correct" setup. They actually run good, they're driveable, and they're pretty reliable. I saw set on farcecrook the other day, the guy was asking $2500, I bet $1500 or less would buy them.


By no means are they as cheap as any single 4 barrel. But they're seriously cool, and way cheaper than fuel injection.


Jimmy Bridges and I recently built a set for a 283 I built for a customer. The other day, I literally connected the battery, stepped on the gas one time, cranked it, and it fired instantly, maintained and idle, and ran perfectly. I've never even set the timing or adjusted them, we fired it, broke in the cam, and shut it off, without every turning a screw.