Reply to "Seeking Carburator Recommendations"

3310 has become a generic carb. That is actually the original Chevy number from the Z28. It's a 780cfm.

Ideally, what you want really is a Boss 302 carb and add an automatic choke OR A 428 CJ CARB. They are both generically the same carbs. Maybe all three are just a little too big for their original factory applications?

The Boss 302 is rated at 780 and the 428 at 735. They are very similar carbs. Both would be bolt ons for the Cleveland (the boss 302 is manual choke though) with a square bore intake and could be run as is if you aren't picky.

I ran that carb on the C (B2). It ran great, fantastic in fact, out of the box but it's now a pretty expensive carb because of what it is for.

You can get very close "continuation build" Holley carbs from Carls Ford Parts. They are not cheap but work well. The difference between the B2 carbs is one has 78 secondaries and one has 82's. You have to ask Carl, which is which.

I think the 428cj carb has 70 mains and 72 secondaries. That would work for you out of the box.

The Cleveland likes the B2 carbs because essentially it is a B2 with more cubic inches, but remember those are manual chokes. You would need to put the Holley electric choke kit on it as well.



Personally, I'm not afraid of the secondary metering plates instead of jets. That's not a big deal at all. You don't need secondary jets. The metering plates are fine. The reality is that 95% of any carb tuning is done in the primaries. The secondaries are going to stay put and you only need secondary jet changing ease if you are doing a lot of changes.

Probably any of these carbs is going to run 67 main jets, 6.5 power valve. The equivalent of 72 secondary jets. The Boss and Z28 both ORIGINALLY had 78 secondaries. Why? Beats me. Those are too heavy even with headers and open exhausts under race conditions.

For a stock 351-cj, low compression, even 70/72 is heavy.

ANNULAR venturis ARE VERY HIGHLY DESIRABLE on a carb.

When I first got my Pantera it was running an Edelbrock intake and the generic, out of the box 3310. Secondary metering plate and all. It ran fine. It just wasn't a race car.



Carbs are like camshafts. People TEND to over do it.

The Boss 302 carb, is actually way to big for that engine. So is the 3310 for the 302 Z28 and as a matter of fact so is the Holley 3259 that Shelby put on the GT350's, a 715cfm originally on the 427 Cobras. Both the B2 and the 289 Shelby, should have had 600 cfm Holleys on them.

I just saw dyno results on a 67 289 HP with 2x4 Holleys and a 68 302 with the 600 cfm S8MS Shelby Holley.

The 289, for a T/A racer with real GT40 heads, made 375hp and the 302 365hp. That is a nice strong number for the 302. That 600cfm Shelby carb runs very well. It doesn't kill torque like a too big carb would.



I ran a 4779, 750 dp on the Cleveland for a long time. I had the primary air bleeds leaned down to stock 600 cfm sizes, so the idle wouldn't smart your eyes. It liked 70 main jets and 72 secondaries as the final set up.

On that carb, as on most Holleys, leaning the idle mixture that means enlarging the diameter of the idle air bleed very accurately with a pin vise and numbered drill bits. This is like setting the a/f ratio on Webers with both changeable air correctors and main fuel jets but once the air bleeds are too big, you are screwed, you can't go back.
Better know EXACTLY what you are doing.

Leaning out the idle screws on a Holley only changes the volume of fuel at idle, not the a/f ratio which is built in.

The 750dp ran to 7500rpm AND even with that set up, plugs were still showing heavy with those jets.



I think that a 600cfm carb will crispen up the throttle on a sluggish low compression 351cj. Been there. Done that. I think a 750 is too big for that engine with the 8 to 1 compression ratio.

The 1850 is lean out of the box but will make as much power as the 750 does when you jet it up. Particularly the secondaries.

It will give you 4 or 5 mpg better mileage and pulls very, very hard in the lower gears at WOT.

It will also have a better idle than the larger carbs do because of a stronger signal to it.



I went with 2 4180 Holleys on my 2x4 set up. 59 main jets and 119 secondary plates. Those are annular discharge venturis and the difference between them sensitivity wise and the 1850 is night and day, AND the 1850 is very good. Annular discharge is just so much better! The carbs also are 4 corner idles which helps a lot also. That's a very tricked out set up.



None of these carbs are perfectly set up for you out of the box. The 1850 will likely come with 62 or 63 mains. That's going to be too lean and would need to be changed. The other carbs probably will like 70 primaries, but come with 67 primaries.

Therefore how they come out of the box doesn't matter all that much. To get them right and pull hard, you need to do a little work with them. Probably just a weekend, uninterrupted, as long as they aren't too big for what you have.



I am not aware of any carb, other than the two Ford carbs and possibly the ORIGINAL 3310, that would be jetted really close to what you need right out of the box.