The Stovebolt Site Forums The Shop Area Engine Shop Monojet vs Carter YF / Carbking

Okay, here's an opinion poll.

Which is better;
A Rochester Monojet,
Or a Carter YF6420?

Boo

This is a very simple question with a very complex answer.

First, my opinion is that any Carter YF (even a seized-up core) is superior to any monojet

The problem with the question is that we are comparing "apples and oranges" as to applications, as the listed YF is for a Foorrdd; and monojets were produced for GM applications.

We have 1210 applications for Carter YF carburetors, many for various GM. It is generally better (if possible) to acquire the correct carburetor rather than trying to adapt the incorrect carburetor.

Jon.

Back when the family shop was a Carter certified service center, we had the slogan: "The ABC's of carburetion- - - -Always Buy Carter!"

I've never had much luck with a MonoJet, even one that's calibrated for the correct application. Carter just builds a better carburetor, but it still has to be set up for the engine is's installed on!
Jerry

I have two YFs on the 39....put em on they worked for years til I got really sick and didn't use the truck for months....now boilin'

I have two Monos on the 37 Packard....Made them outta a dozen or so cores....Then had to mess with them as per 'inliners directions' Had them off and on many times....they now work pretty well on a Very Custom motor

So YFs WIN!!!

But if you have nothing else to do but get madd at your carbs and keep tuning ..... Mono!

The reason I specifically mentioned the YF6420 is that it is the carb that came on many 240 and 300 ferds. It draws 10 more CFM than the monojet that came on my chevy 250, so it ought to be about right. It has taken me a long time to decide between hopping up my engine really radical, or just making it a real good runner. For my purposes a real good runner may not be as cool as a hot rod, but it definitely makes more sense.

I've been running a Holley / Weber 5200, but in a lot of ways I'm not all that impressed with it. Believe it or not I got better gas milage with the NAPA rebuilt monojet.

So, my thinking is that with a mild cam, some real basic work on the ports, and the mandrel bent exhaust from LMC ( flows 20% better than stock) a properly tuned Carter YF6420 ought to work real good whether I'm high tailing it down the freeway, or putting around out in the hills.

Or,
perhaps,
there may be some other version of the YF I should consider.

Boo

Boo -

Carter YF 4085s, 4369s, and 4371s were all original equipment on 250 CID Chevrolet with standard transmission. Carter YF 4085s, 4370s, and 4372s were all original equipment on 250 CID Chevrolet with automatic transmission.

Of possible note to several of you: 4371s was also original equipment on 292 CID Chevrolet.

While the YF for the Foorrdd would probably work, a YF specifically calibrated for Chevrolet would probably work better. We have stated for years that the most expensive carburetor one will ever buy; is one given for free by a friend or neighbor which is incorrect for your application! :p

Also consider that all the the YF's in this post as well as the Foorrdd YF originally mentioned by Boo are smog emission carburetors, so may (or may not) be lean on idle (early smog carbs were pretty much only effected at idle).

Jon.

Thanks Jon; I will heed your advice if possible. On the other hand I am high bidder on a new YF6420 reman on ebay for $5 plus $15.00 S&H. For $20 bucks I'll give it a try. If I don't like it, I'll add it to the ever growing carb collection under my work bench And then move on to one of the models you listed.
Boo

Boo - we can help that pile of unused carbs, we have over 150,000. That is, if you have a large enough work bench

Jon.

Well, Jon, I was outbid, so now I'm going Ebay shopping for one of the models you mentioned. Unless, perhaps, you can "cut me a deal"!

Boo Radley

FWIW , I have always been a Rochester 'B' series enthusiast as they're simple and like the man said , made for the application .

_However , I recently had the opportunity to rebuild Jim's YF's on his 302 Jimmy engine , they are the Carter replacement # 964S carbies for the Chevrolet 6 cylinder engine from 216 to 235 and they were both stock jetted , these carbies are _really_ well engineered IMO and I may well try one on my old 235 as they seem to carburet more smoothly than the inexpensive Rochester B does .

If you have the time to hunt up the right one , methinks the YF will be the better carby , it bolts right up without any mods whatsoever too .

The cool thing is : every single part in these YF's has a part number stamped right into it so there's no " oops ! " like in a Rochester B when you're assembling one good one out of many old tired cores.....

It helped that Jim loaned me his HUGE carter shop manual and fatory master carby tool set so I could easily make all the pertinent adjustments

What Nate doewsn't say is that my truck was down since Dec last year

I have been so sick and just trying to stay alive....the truck just sat

Nate's efforts got the truck going again

That's what is special about bolters

Thanks Nate