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Got my MC2150 dialed in...

4K views 44 replies 17 participants last post by  scrapman 
#1 ·
Title says it. Got the 2150 from the ebay guy, install was pretty straight forward, new DUI at the same time, but had a nagging bog, hesitation, stumble...something, when taking off, and when accelerating with slight pedal from cruising speed.

Checked timing many times, with light, and vacuum guage as well as mixture adjust, choke adjust. Just couldnt get rid of the stumble. Checked the power valve, and it held with a vacuum pulled on it. Played with accelerator pump linkage position and holes. Still no joy.

Decided to try using some of the PV and jetting combos that worked for others here, and went from the 8.5 PV and 49 jets, to a 6.5 PV and 47 jets. Now runs like a scalded dog, accelerates smoothly with none of the afore-mentioned issues, and pulls hard to 75mph with the new 4.56's, at which point I let off. Also noticed that the smelly rich fumes are significantly reduced...really, they are not noticeable anymore.

Just wanted to share the combo that worked for me at basically sea level in Florida.
 
#4 ·
He's a good guy to deal with. Give him specifics (I live a 8,500 ft elevation for instance) and he will pre-tune the carb. Mine arrived and was plug & play and required very little adjustment.
 
#10 ·
Hey Wayne,

Do you happen to know what jetting/air combo he put in yours?

We should start keeping a database of jetting combos that work with each carb at certain elevations. A few shops offer custom-jetting , but I don't sense any of them have it dialed in. Too many variable, perhaps.

National carbs in another excellent company to deal with. They custom jetted my carb for no extra charge. The primaries were perfect, but i did need to tweak the secondaries.

Op, congrats. I know how satisfied you must feel. :cheers2:

Matt
 
#5 ·
I have the same problem (rich fumes gas smell) with my 2150 carburator on my 258 engine and bought it from the Ebay guy also. I have done pretty much everything you described: fuel air mixture settings, new vacum hoses, no gas leaks around the tank, reconect charcoal canister, choke adjustment etc.I don't even know what size jets i have now but I would like to try different ones, i've never worked on the internal parts of a carburator before. What is a 6.5 PV? Did you have to remove the whole carburator off the jeep to change te jets or can it be done on the jeep? where did you get all the parts needed? Do you have a write up for this? thanks for the help
 
#6 ·
Got the 6.5 power valve from NAPA, and the jets ordered on line.

You have to take the carb off to change the PV. Its on the bottom front, under the little cover held down by 4 screws. The jets are easy to change with the carb on or off, but you do have to take the top off the carb to change them. I suggest picking up a jet tool, as the slot can get boogered if you are not careful.
 
#12 ·
Got the 6.5 power valve from NAPA, and the jets ordered on line.

You have to take the carb off to change the PV. Its on the bottom front, under the little cover held down by 4 screws. The jets are easy to change with the carb on or off, but you do have to take the top off the carb to change them. I suggest picking up a jet tool, as the slot can get boogered if you are not careful.
Got a part number?
 
#9 ·
That's a good idea...I'll send him an email with what I did.

Other than that, I'm pleased with the carb. I know I could have done some legwork myself and saved a few bucks, but this was about as simple as it gets...new carb, gaskets and adaptor with studs, 1 transaction, and pretty good install notes as well, if you need them.
 
#14 ·
A part number would be great a I tried to look it up online at NAPA's site but couldn't locate it. I wasn't looking for Holley though as I didn't know if they were the same as the motorcraft. Since I don't have the vac line going to the PV does that mean mine is a single stage?
 
#15 ·
If your power valve has a bowl on it it's likely a 2 stage. If it's flat it's a single stage.....

I have both types. Tagged for more info on best PV to use. Getting black smoke out of one carb when I mash it (46 jets, unknown PV) and the other one runs great (47 jets, unknown PV).

I've always just used the PV that came in the rebuild kits, but they never have any markings on them.
 
#17 ·
Carb on 4.0?

Hi, Ive been embattled with a 88 yj 4.2 to 4.0 swap. My old 4.2 has climbed its last hill and now is being replaced by a 03 4.0 out of a grand cherokee. Having gotten the motor cheap i'd like to use it but now I am at the point that i would like to ditch the f.i. and go back to a carb. What I would like to do is find a carb to retrofit my stock 4.0 intake manifold. i think if i can find a carb in the 400-500 cfm range with a base size of no greater than 3" square I might be able to cut a square in the manifold tread some screws in and be in luck. Have you ever heard of anyone doing this? thanks
 
#19 ·
I went to NAPA today looking for that 6.5 pv for my 2150 Motorcraft and no luck. I got my new 47 jets today but I can't replace them yet due to the ones on the carb having a cap on and I don't know how to take off. I can't get to the jets without removing them, they look like brass caps.
Did anybody have this problem removing these caps off?
 
#20 ·
Couple of questions:

1. Is there anyway tell which PV I currently have on my MC 2150?

2. A part number for the 6.5 PV would be great. I found a few on the NAPA website but it wasn't immediately clear which would work for my application.

I have almost the same problem as the OP and the PV diagnosis sounds spot on. I too bought my carb from the eBay guy and have yet to get a response from him about the issue. Not saying he won't respond, just that he hasn't yet.

Hopefully he will because he sure does talk a big game about after sale support.
 
#21 ·
Couple of questions:

1. Is there anyway tell which PV I currently have on my MC 2150?

2. A part number for the 6.5 PV would be great. I found a few on the NAPA website but it wasn't immediately clear which would work for my application.

I have almost the same problem as the OP and the PV diagnosis sounds spot on. I too bought my carb from the eBay guy and have yet to get a response from him about the issue. Not saying he won't respond, just that he hasn't yet.

Hopefully he will because he sure does talk a big game about after sale support.
Any holley 6.5 single stage power valve will work. A quick google of holley 6.5 power valve turned up several places to buy. Here is one:

http://www.summitracing.com/parts/hly-125-65?seid=srese1&gclid=COzF6cTUjLkCFfFj7AodlXYAww

The only way to tell which one you have is to take it off and see what numbers are stamped on it.
 
#23 ·
The power valves are on the wall at any auto parts store in the performance section. They usually have more sizes then just 8 or 8.5 which is what comes in the kits, I think.

You can pull those brass caps off
 
#29 ·
You're going to have to pull the top off and see what is stamped onto the jets. If I recall correctly, the eBay guy tries to jet and tune your carb based on the info you provide when ordered.

Its close...but fine tuning makes it better. You have to do this with any carb you buy, as there are just to many variables to factor in. Once you determine what is in the carb buy a couple sizes of jets higher and lower then swap them out till you feel its at its best.

Tuning a carb is becoming a lost skill, and it usually takes a couple of tries to get it right, but its worth it.
 
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