The Stovebolt Site Forums The Shop Area Engine Shop carter or rochester which to rebuild 1 barrel

I have two carbs from older model 235's looking for any input on which carb to clean and rebuild if anyone has any pref. good or bad love to hear about it.

it's going on '61 235. intake is 3836922 and the head is 3836848.

it's in a '51 3100 1/2 ton. Intened to be a nice easy rider, nothing special.
Thanks, Mike

both

Allot of guys prefer the carters. That being said, I've run a rochester on my current truck for the last 11,000 miles with no trouble. Its what I had on hand, so that's what I used.

Truth is, if they are good cores, either one will make a good carb once rebuilt.

The Carter YF, if used with E-10 gasoline, will eventually need rebuilding, as the ethanol will kill the diaphragm-style accelerator pump. Approximate mean time to failure:

Driven daily - 3~5 years
Driven weekly - 1~2 years
Driven monthly - every 6 months
Driven less often than monthly - every other time it is driven

The rebuild simply involves disassembly, cleaning, and a kit.

The Rochester type B will eventually warp due to insufficient screws holding the airhorn to the bowl. This will cause the power valve to always be open, and the engine will run extremely rich fouling plugs, washing oil from rings, and extremely low fuel mileage.

Approximate mean time to failure with either new or straightened castings - 5~7 years.

Straightening of the casting is done by heat and pressure. I have discussed this before on these forums. For step by step, please do a search. It is VERY labor intensive. If this must be done professionally, VERY expensive.

If one compares the two carbs, each correctly restored, the Carter will do slightly better in all categories other than on a points judged vehicle.

Put a different way, we sell the Carters for a substantial amount, and give away the Rochesters (unrestored) with a kit order of 3 kits.

Your choice.

Jon.

Your point is well taken. Gasoline in being "double blended" in many areas. Because of tax credits, %10 is blended by arrival at terminal/port then %10 blended again at local supplier/delivery co. Why don't your suppliers make the diaphragm out of a material that withstands ethanol, for the YF? E-10 is not going away soon.
Also, what carb would you recommend that would have good MTBF for this engine.

OH, if it were that easy!!!!!

The problem is three-fold:

First, according to our all-knowing government, neopreme is approved for use with ethanol. Thus, the suppliers that make the diaphragms ARE using an approved substance, even though it doesn't work well.

Second, the accelerator pump diaphragm is part of the metering system. It is designed to flex a given amount with a given imput. Change the amount of flex/input, and the height of the metering rod in the jet would change, thus changing the dynamic calibration of the carburetor.

Third, I have checked with a friend that manufactures kits for fuel pumps. The material he is using is buna N rubber with embedded fiberglass particles for strength. Just assuming that the flex rate for the buna N is identical to neopreme (it isn't); buna N/fiberglass does not exist in the proper thickness for the YF diaphragm. And there is insufficient quantity of carburetors left to justify the minimum order to have buna N produced in the proper thickness.

As to what carburetor I would recommend?

Well, the YF is still a great carb, with the caviat of the periodic replacement of the pump diaphragm. And the YF is reasonably priced.

Both Stromberg and Zenith offered excellent carbs with ethanol friendly accelerator pumps, but at a higher initial cost.

Carter also offered a WE with a normal leather accelerator pump (730s was released for the Chevrolet 216, it would probably work well with the 235 on a 216 intake manifold). I have never researched this to check the calibrations. And remember, Chevrolet used the 216 W-1 on 235 engines in the 1940's.

Jon.

In the Model B portion of Doug Roe's Rochester carb book (first printing) he mentioned that some of the earliest model Bs did have some problems with their airhorn castings warping, But he says a design change corrected this problem and subsequent models were trouble free. Having never had this problem with the several model Bs I have owned (all passenger car '54 and later), I would think simply sanding the gasket surface flat would be sufficient. How much do they warp? Never had a Carter YF, only a set of YHs and some WGDs, I think they are all a related design that uses metering rods and diaphram accelerator pumps. I like the metering rod system but am not a fan of diaphram style pumps. Over all I would prefer the model B (but I just dont like their nasal sounding part throttle whistle when used with unsilenced air cleaners). My two cents.

The early B's warped in a couple of years. I was referring to the newer design at 5~7 years in my previous post.

Sanding the edges makes the problem worse, as one removes metal, plus removes the ridge that helps the seal.

And I agree with you about the diaphragms.

Jon.

carbking -

Thanks for the info.

> Anyway to tell if the power valve is open in my Rochester B while it is on the engine without taking off the airhorn?
> If it is always open, will it damage the engine?

'54 3104
'54 235 w/'59 head
Rochester B (no tag, just casting numbers)
New NAPA rebuild kit a year or two ago
Carb oozes a little gas
Non-ethanol gas
Never checked the mileage - probably over 12MPG
Engine runs good
Plugs are soft black
Less than 1,000 miles/yr

Carbking,

Where would you put the Rochester Monojet in the spectrum of carbs?

Lonnie - use a tailpipe sniffer. If the A/F ratio is less the 14, the power valve is probably open.

Wally - (strictly opinion, but you did ask). I don't like ANY of the Rochester single barrel carbs; whether you are talking B series, M series (monojet) or R series. On the other hand, with the exception of the AA and BB series, the Rochester 2 barrel carbs are in the top 5. Ditto for both the Rochester 4 jet and the Rochester Q-Jet.

I guess my top tier of single barrel carbs would be:

(1) Carter WA series
(2) Stromberg B series and Zenith 228 series
(3) Carter W series and Zenith 28 series
(4) Carter Y series (only this low because of the ethanol/diaphragm issue
(5) Holley 847 series

There are other good single barrel carbs that don't make the above list because of the cost of repair parts. These would include, but not in any order: Stromberg A, E, and W series; Zenith 20 and 23 series.

Series that I don't really care for would be, again not ranked: Carter AS, BBR, BBS, and RBS series, all Holleys except the 847 series, all Rochesters, Stromberg D series, and Zenith E and IN series. And I probably forgot something!

Remember - all of this is my opinion, others will differ.

Please understand I am not saying the single barrel Rochester carbs cannot be made to function (for awhile); I just don't like redoing something every so often because the manufacturor failed to spend a few extra cents to prevent the issue.

Just as something to shoot for: the dual 4-barrel Carters on my 1968 non-GM 390 truck haven't been touched in roughly 10 years (other than to change metering rods for E-10). At 70 MPH, the truck will get 22 MPG on gasoline, 19 MPG on E-10. The carbs are set up so that both run simultaneously.

And Ed - here is a picture of the "ridge" used to help seal the gaskets. Sanding and removing this ridge will guarantee issues:

http://www.thecarburetorshop.com/Rochestersealingridge.jpg

Jon.

Hi Carbking.

I have a NOS WA-1 413S that I want to use on my 1955 235 engine.
Is it possible to find out if the nozzels and settings are compatible with that engine?

Regards Torbjorn in Norway.