Carb advice

I have a 1978 Cj5 with a 258. Right now I have a Carter YFA 1BBL that seems to suck alot of fuel (15MPG-HWY), and I can't get over 3,000 RPM's. I think I want to go with a 2 BBL. I have heard the 1 BBL just isnt big enough to begin with. any suggestions on a swap to a larger carb, can I get adapters to keep my 1BBL intake and use a 2 BBL or is that just a waste? Anyway, just some helpfull suggestions on trying to get a bit more power and reliablity while at the same time replacing this junk carb that loves to leak fuel from the venturies (only 6 months old ). Thanks

 

15 mpg for a CJ is not bad. You may be able to get a few more MPG from it, but I predict you will top out there.

If you can't get over 3000 rpm, then something is broken. The YF is a good carburetor, if properly rebuilt. What do you mean it dribbles from the venturis? :? There's only one venturi in a 1V. Maybe it leaks from the float bowl?

A 2V is a good upgrade, but I believe you will be disappointed if you think it will solve your problems.

 

I have been researching this alot.. everything I find says these 1 BBL carbs are junk. this carb was a new remanufactured unit less then 6 months ago. when first installed I was at about 21 MPG. Now when on a rough road I get fuel spilling in and then it leaks out the carb from the top. seems like a stuck float. When driving on smooth surface its fine. I also had it rebuilt to try to fix this.. didnt work. I also read that because the two BBL carbs have TWO small venturies, when under normal driving you actually use less fuel untill you kick in the secondaries. Also read these carbs where stock on 4 cyl modles and on the six are under carbed I could be way off and what I read was just yappy people like alot of places. I have had great luck here and all GOOD info. I guess the real question I have is will I notice a difference if I get a 2 BBL ( like the weber )and will it really be worth it?

 

First, I don't think it's worthwhile to change to the 2V carb unless you also change to a 2V manifold. If you do that, I expect you will see some increase in power.

The YF was used on lots of different cars for many years, and has no serious flaws AFAIK. It was used on the 134 cid 4-cylinder Jeeps as well as on the 232 and 258 engines through the late '70s.

I suspect you are confusing the bad reputation of the 2V Carter BBD carburetor, which was used on CJs starting around 1979 (?), with the Carter YF 1V carb. Everybody hates the BBD, but not the YF. The YF is fine.

The guys who have the F134 in early CJs have found that the carb kit from "The Carburetor Shop" provides all the parts you need, and the correct parts. Supposedly most kits do not include the proper seal to go around the diaphragm lifter link in the carb. This has no effect on the street, but on a Jeep, fuel sloshes out.

Yes, some carbs have booster venturis. However, that is not the venturi, in the sense that a 1-barrel carb only has 1 venturi, making it a 1V carburetor. Semantics.

hth!

 

ok.. this makes me think now. and you have given me lots of info. Ok.. so, i want to get the carb that WORKS on a JEEP with the mess. I don't have a problem sticking to a 1 BBl.. can you recomend one for me? I know this one is not original because i could only get what I could get here in Mexico. here is what I have now These are all the marking on the carb: Carter Manufactured for Ford Motorcraft, 2251, 2085, 6-2037. thise are all the numbers I can find on the carb.

 

Sorry, the numbers don't mean anything to me. A YF is a pretty generic carb though. Rebuilding it is not rocket science - somebody in Mexico should be able to help you. I don't know of any other source for the diaphragm lifter link seal.

Try searching old posts for information on the YF. Go to Google and enter "site:earlycj5.com Carter YF leaks" and you'll find lots of relevant posts.

My guess is that the fuel sloshing out does not have anything to do with the loss of mileage. 21 mpg for a CJ is phenomenally high, and your measurements might have been mistaken. High teens is excellent for a CJ of this vintage. If the engine is running fine and the plug color looks good, it's probably running normally.