The Jets

[Bobaloo]

Okay, we have the 2 AFB's atop the Offy intake. It idles and it flies wide open, but it soots up the plugs, is unpleasant to your eyes, and at highway speed it's like it has the most radical cam ever made! Also the front carb stays wet all the time! What jets do you guys recommend on a low performance engine like my 1958 348.

[dq409]

First check and see if the meter rod/rods aren`t stuck.
can`t say what jetting though,,

[Ronnie Russell]

Bob, What AFBs??? Identification please.

[Bobaloo]

I have a 1405 Edel and a Carter 625. I have no idea what metering rods, jets or anything else, but I can find out if directed.

[Ronnie Russell]

Bob, One 500cfm carb would be just right for a 250hp 348. You can see the problem attempting to use 2-600s. Use .098 primary jets and .089 secondary jets. Use .073x.052 metering rods. Even then , you may have to adjust linkage so that front carb does not open 100%. I understand the appeal of 2x4s. They look great, but you may have to settle for the look only , the engine just wont handle that much cfm.

[1958 delivery]

Front carb is wet, check for float level too high also.

[models916]

I cured that problem on mine with off road needle and seat on both carbs.

[Bobaloo]

Okay, I see I have too much carb. Back on July 11th when I started the thread Offy Intake you guys told to go for it, but now I see that you mentioned 500 cfm carbs instead of 600's. I didn't realize it would make that much difference. Originally I wanted to actually use one and dummy the other. I know now that will not work. I do not need 8 barrells, is there a linkage thing I can do to cut down on the amount of gas I am getting there?

[Ronnie Russell]

Bob, I didnt mean to sound like your set-up will not work. You must use progressive linkage. Then it is just a matter of playing with the stop. No big deal. But first, it is neccessary to ensure both carbs are healthy. I would agree with others that you have a problem with the front carb. If both carbs are working properly, and you have progressive linkage, you will be able to use what you have and have good drivability.

[Bobaloo]

Thats what I need to hear, thanks Ronnie. My mechanic is going to go thru the front carb tonight, and since he works for an auto parts store as well, get the jets and metering rods you suggested. Thanks.

[buzzard]

If the carbs you have don't work out like you need I have a pair of 400 cfm carbs [ small tops ] that might be a lot closer you need. :coffee:

[425/409ER]

Ahh been there done that with the big carbs on a sbc so here is what I did. I had 2-600 carters that I diabled the secondary sides on both of them and ran on the primarys. The car ran good and was not bad on gas had to jet down though but on my 400sb that engine was fine with all the barrels opening up. I has a friend back in the early 70's that had a tri-power 348 took off the small rochesters and put on 3 holleys as they looked cool untill he got his a** handed to him by some dude one night. Needless to say the next day the small carbs were reinstalled.
Try running on the primarys see how it runs and go from there.

[Bobaloo]

Sometimes I can't see the forest for the trees, = what a great idea, I get the look, (all I am really after) and save some gas. :cheers Thanks 425/409ER.