Correct Carb for 88 4.2?

tclaremont · 07-19-2009, 02:17 PM

I just bought (about 30 minutes ago) an 88 YJ with the 4.2 / auto trans. The engine dies when going around a corner. It acts like a float problem in the carb. The PO says that the carb that is on there is an "upgaded carb", and I am thinking that it runs too rich, too.

I could rebuild what is on there, or I could seek out the "correct" carb if they are readilly available and not too outrageously priced.

Can any tell me what carb I am looking for?

Thanks!

**jeeepguy** · 07-19-2009, 10:44 PM

Do NOT put on the "original" carb... it is the Carter BBD and is notoriously finicky. Put on either a Weber carb or a Ford MC 2100. Best bet is to convert the whole thing to the later MPI setup and be done with the carb altogether.

Good luck...

Sxinc · 07-20-2009, 12:25 AM

The Carter is a pos I've been swapping and fighting with 2 of them and finally bought my Weber k551 for 320 now waiting for it to get here

tclaremont · 07-20-2009, 05:54 AM

I know the BBD is crap, but I did not realize that it was the original for a Jeep 4.2. Perhaps because you see so few of them still on Jeeps.

I am not afraid of a carburetor, so going to FI is unnecessary. The ultimate carb for a 4.2 would then be the Webber?

I see listings on ebay for emissions versions and stepper versions or some such thing. Since my Jeep does NOT have the original carb, how do I decide which one I want?

Sxinc · 07-20-2009, 07:03 AM

I would suggest a weber if you plan to offroad but if your using as just driving around then go with the motorcraft 2100.
I just purchased this one..
http://www.4wd.com/productdetails.aspx?partID=13835 its the K551 34/34
and also people also suggest the Weber 32/36

**bernm8r** · 07-20-2009, 07:30 AM

Welcome to the forum. I have the MC2100 and am very pleased. This forum has been excellent for searching for anything you want to do or need to do to your jeep. there are lots of great folks here to help you as well. I am biased to the MC2100 only because it was so simple. I was about to pull the trigger on the weber but I found lots of threads about the difficulty of tuning it so I stayed away. I have the install docs so if you want to PM me you can read it and decide for yourself which you want to do. Good luck
Bern

**vmann7** · 07-20-2009, 07:30 AM

Pics of the "upgraded carb" so we'll know where we're starting at, maybe just a simple rebuild.

**rustywrangler** · 07-20-2009, 07:32 AM

Quote:

Originally Posted by vmann7

Pics of the "upgraded carb" so we'll know where we're starting at, maybe just a simple rebuild.

Pics of whatcha got first. Could be throwing $300 at a .50 cent problem by replacing it.

tclaremont · 07-20-2009, 11:33 AM

I totally agree, guys. I am 90 percent sure that I have the Motorcraft carb, but I have yet to trailer the beast home. I will confirm ASAP.

As for symptoms, you need to pump the pedal 10 times to get it to start. It then starts and idles fine. When driving, it sputters pretty often from off-idle right up through the rpm range. While this could be ignition related, I find that it dies when I make a turn of any real size. I suspect that the float is fubar, and it is rearing its head when the fuel level moves around in the bowl.

Once I get it home (maybe tonight) I will pull the plugs and see what they look like. I will ensure that the vacuum lines are as they should be. Checking the fuel filter is always a good idea. Finally I will confirm
exactly what the carb is. If a 15 dollar rebuild kit is in order, so be it.

Since I dont have the truck in front of me, can someone tell me how to identify the carb? Is there a tag or stamping on it somewhere that will ID it?

**rustywrangler** · 07-20-2009, 12:16 PM

Once you get it, take a look at the distributor wiring and see if anything has been spliced in. If you have an aftermarket carb, you need to do a "nutter bypass" of the computer. It almost sounds like that has not been done.

StitchMup · 07-20-2009, 12:48 PM

Quote:

Originally Posted by tclaremont

I totally agree, guys. I am 90 percent sure that I have the Motorcraft carb, but I have yet to trailer the beast home. I will confirm ASAP.

As for symptoms, you need to pump the pedal 10 times to get it to start. It then starts and idles fine. When driving, it sputters pretty often from off-idle right up through the rpm range. While this could be ignition related, I find that it dies when I make a turn of any real size. I suspect that the float is fubar, and it is rearing its head when the fuel level moves around in the bowl.

Once I get it home (maybe tonight) I will pull the plugs and see what they look like. I will ensure that the vacuum lines are as they should be. Checking the fuel filter is always a good idea. Finally I will confirm
exactly what the carb is. If a 15 dollar rebuild kit is in order, so be it.

Since I dont have the truck in front of me, can someone tell me how to identify the carb? Is there a tag or stamping on it somewhere that will ID it?

Easy ID method for Carter Carbs.. If it wont run its probably a carter..
Vacuum Lines? We dont need no stinkin vacuum lines?
Seriously if you end up doing a swap, I have the mc2100 on my 88 and my buddy next door has the weber on his 89, both run great. just dont tell him that i said that.

nickdestfino · 07-20-2009, 01:26 PM

Morning, I can't speak for the mc 2100, I ran a weber 38 for a year or so, only negatives I had were didn't like cold starts and really didn't like being hot. Had a bad vapor lock problem and a trail once. They require a lot of up keep to stay running proper gas mileage sucked as well. A big bang for your buck is the head conversion in both mileage and power. Ultimately I would work towards doing the FI and head conversion on your motor. If I can keep my foot out of it I've gotten 21 mph on the highway without doors on 35's

Ra8erFan · 07-20-2009, 03:11 PM

Weber 38/38 has run great for me. as stated above your fuel milage won't be great. There are some smaller Weber carbs out there to that might work for you better.

**zeus87gn** · 07-20-2009, 03:22 PM

I prefer the Holley 350cfm. To me it's a perfect match for the 258. I have a link to my thread that details what I did. There are a few of us Holley owners who wouldn't have it any other way. Myself mainly because I don't like Webers.

Now that I have my Holley set up right, I haven't had to touch it in quite a while. It runs just fine. It doesn't like to be cold tho. It does act up a tad in the winter, but once the engine gets up to temp it's business as usual.

nickdestfino · 07-20-2009, 05:16 PM

I ran a 500 cfm holley for a min. but at extreme angles it seemed to load up and stall. I'm not sure if holley has overcome this problem or not.

07-20-2009, 12:16 PM	#10
rustywrangler Got my eye on you..... Join Date: Apr 2005 Location: Syracuse, NY Posts: 18,657 Profile Gallery Classifieds My Jeeps	Once you get it, take a look at the distributor wiring and see if anything has been spliced in. If you have an aftermarket carb, you need to do a "nutter bypass" of the computer. It almost sounds like that has not been done.