The Stovebolt Site Forums The Shop Area Engine Shop Getting Frustrated with Rochester B

I needed to replace my carb. I went to O'Reillys and bought a Tomco rebuild. It was a mess. The fuel inlet gasket was leaking fuel. I replaced that. Got it back in the truck and both main gaskets were leaking fuel as it was warming up. I took it back. They replaced it. Took the new one home and the fitting on the bottom that attaches to the intake is a completely different size. So, I take that back and asked for my money back. Now I'm at a loss. How do I know the next one that I purchase is the going to be the right size and not leak every where. Arrhhhh.

Calm down. Piece of cake. Read the numbers in the carb. Order from a carb place online, not O'Reilly's. Order from CarbKing here (The Carburetor Shop, Eldon, MO. online) or Mike's carburetor shop online. Either of these guys are nice people and will communicate with you by email and/or phone. Give them every number you find and pic or two. Mikes Carburetors has several good videos online on how to rebuild a B. Both websites have good info and pictures to ID a carb.

I'll look into those options. Thanks for the input. I also just found a local carb shop that also sells these. I'll swing by there and also look at the above.

The problem with carburetors rebuilt in a production environment is they do not keep the original parts together. When they disassemble all of the uppers go in a bin and so on. After cleaning each carburetor is assembled with mis-matched parts.

What is wrong with the carburetor off your truck? If possible, rebuild it with the kit and instructions from Carb King. If that is beyond your comfort level, take it to your local shop and see what they can do. These carbs can be rebuilt, the biggest problem is wear of the throttle body around the shaft, which is repaired by bushing the hole.

Matt, another vote for carbking. Do a search and check his contact info at the bottom of anything he's posted. Phone calls only and only certain days. I visited with him last year (?) and bought a NOS Zenith replacement for my 47,000 original mile Rochester. Best upgrade I've made on my '51. Next best is the T5.

Good Luck
RonR

Jon (Carb King) has been trying to give away a huge supply of "rebuildable core" Rochester carburetors for years, after giving up on trying to make them work right. So far, no takers! Unless the little triangular brass tag is still on your carb, there's virtually no way to identify what you have or order the right parts for it. There are no usable numbers on the castings. Use the Rochester for a stinky paper weight and buy a Carter carb from Jon that's calibrated for your engine.
Jerry

Carters are good carbs. So are Rochesters. If you find 4 digit or 5 digit numbers on the carb mounting flange bottom or other places, add 700 or 70 as a prefix and that is your number. As I said, these two guys can ID any carb close enough for a carb kit part number. Sometimes these carbs get parts from other carbs but are still buildable. Any carb can get warped or unbuildable.

A "local carb shop" can be worse than O'Reilly's. They hire off the street and "train". They need the income and will tell you or do anything to get it.
Jon and Mike don't "need" your business. They just "need" to tell it like it is and if all is OK, they will supply kit or carb or service. Rebuilding is a DIY effort if you study the available info and you are clean an careful. All you want is the correct kit. The problem with DIY is you don't know when a carb is not rebuildable/warped/screwed up, etc.

With the trouble you have described, you are in an area of either out of your expertise, some kind of unbuildable carb or bad/wrong kit.
You said you need to "replace" your carb. You are probably right. Buy a rebuilt carb from Jon or Mike. Whatever one they say is for your truck motor. I advise you to ALWAYS mention the year, make and model of the truck and motor when posting.
Don't start thinking Holley or clones.

Hi Matt.
What engine? What year? Manual choke or automatic?

In September I posted lots of information on the Rochester carburetors...emphasize the word lots. If the castings are not straight, I do not believe for a moment your Rochester will ever be worth using and out of 5 I dissected all were warped. I spent a lot of time (and money) showing everyone here how they can be straightened rather simply using a gas grill, 4 screws/nuts, a dial gauge and a piece of 3/8" thick metal. If they're warped, they'll seep fuel at the air horn to bowl mount and you'll also lose vacuum needed to keep the power piston off the power valve ball. There are about half dozen other things that will make trouble for you.

The Carter carburetors were also discussed in September. They're a different design entirely and I believe will work better than the Rochester...if and only if you use the truck frequently. If you drive your truck once every few months, you're going to have trouble with almost any carburetor using today's gasoline. The Carters will suffer cracked and useless accelerator pumps. The Rochesters will suffer stuck and gummed up power pistons and deteriorated and dried out accelerator pumps.

Whatever you do, please don't buy a carb from O'Reilly's, Auto Zone or any of those places. Please go read what I posted. Learn about the animal and then you can deal with it.

Can I add a question onto this topic...if your truck is going to be sitting for several weeks at a time without cranking, is it smart to put an inline shut-off valve ahead of the carb, and run the carb dry before shutting the truck off?

Not a bad idea Patrick, but I'd be inclined to doubt it would do much good. The problem with the Carter is the neoprene accelerator pump will be damaged when it dries out (after exposure to the ethanol gas). This means your pump might only last a few months. The problem with the Rochester is the power piston will wick fuel up into the gap between it and the air horn shaft and this will dry as a sticky varnish-like mess. Given time, it will cause the power piston to stick in the down position, and I have not observed that it will correct itself. This will make your carburetor run as rich as it possibly can. Also the ethanol won't do your accelerator pump any favors, either. So either way you're sort of goosed. The best of worlds is to drive them or start them often enough that your carb doesn't dry out, but I realize that can't be done by everyone. Personally I'd avoid the Rochester in this case, get a Carter and buy a few replacement accelerator pumps so you'll have them as needed or try one of the ones being sold on eBay claiming to be resistant to ethanol (they are orange in color and have a fiberglass web molded into them). I don't know if they are as good as they claim to be, but it is worth a try, I suppose.

Jon G, that sounds like a good option, but I am going to be running a 261 shortly, and not sure if a Carter will provide sufficient air flow for it. I am tempted to experiment with Jerry's idea of the 258 AMC carb.

Patrick, the 261 runs the same intake and exhaust manifolds as a 235 so swapping carbs might not produce a noticeable gain in performance RPM-wise. Finding one that's jetted for a similar cubic inch displacement engine would probably improve the low end and midrange performance, or at least provide a good starting point. The 261-specific Rochester B is a scarce item, and I'm sure it would have all the characteristic Rochester headaches as well.
Jerry

I'm just looking for a "best, most reliable" option to use. I have a Rochester B (not the 261-specific) that will be used for now.

This would be either a Stromberg or a Zenith. In addition to adjectives "best" and "most reliable", you can also add "most expensive".

Jon.

Or a Carter 3211s. That is a very nice carburetor with an automatic choke and occasionally one shows up on eBay.

Lots of good info. Live and learn I guess. I found a local shop that advertises that they work on Rochester B carbs. They discussed the warping concerns with me and said they know how to repair it. Hopefully I'm on the right track. I'm bummed the first carb that came with the truck is long gone.

Second question. I asked about a port on the side of the carb. He explained thay it was a vacuum like that attaches to the distributor. I told him one was never plugged in. I looked at a bunch of pics online and looked at my truck again. The mentioned line from the distributor runs to a port on the intake. If that is correct, what is done to the port on the carb?

Attached a pic, also here is a video of me following the line.
Me following the line...

Its a 1963 230. Manual choke. I drive it on the weekends, but that's about it....

The proper vacuum feed to the distributor vacuum advance is almost always taken off the carburetors "controlled" vacuum port. This vacuum port can usually be identified as being slightly below the throttle plate cross shaft. Basic operation:

1) At idle the throttle plate is nearly closed, cracked just enough to allow "some" air to pass through the venturi to mix with the low speed/idle port fuel mixture. There's very little vacuum present below the throttle plate so NO vacuum is passed to the distributor's vacuum advance. You don't need timing advanced at idle.
2) As the throttle is opened, vacuum is generated under the throttle plate which is then applied to the distributors vacuum advance which activates it (advances timing)
3) Vacuum will continue with increasing RPM until the throttle plate hits a certain degree of open when the vacuum under the plate ceases to be enough to operate the distributors vacuum advance. This is OK as the mechanical advance has taken over by then.

Vacuum advance is off at idle, begins to advance timing at low speeds to mid speed then drops away at higher RPM and/or acceleration.

The vacuum for your distributor should come off of the control port on the dist and not from the manifold as it probably provides vacuum at idle (not needed) and at higher RPM when the mechanical advance should have timing advance control.

Easy way to determine which is the control port is by placing your finger over the port, at idle there should be no vacuum (suction), open the throttle a little and you should feel vacuum (suction)..

FWIW, I have had good luck with replacing the Rochester B/BCs due to recurring leak/warpage issues with the Chevy-spec code 14-xx Stromberg carburetors (BXDV-3 or BXV-3s) on 235s, and using BXOV-2s on the 216s. The nice thing is they have leather accelerator pump seals, so will last better with ethanol (E10) fuel, to Jon G's earlier comments. The Stromberg's pop up regularly on eBay, sometimes well priced, and sometimes at ridiculous prices.

Many times, I've found NOS or old-rebuilt Stromberg carbs at very good prices, just takes some shopping and patience. It's getting much harder to find BXOV-2s that are good and affordable, especially if they are the later 1-5/32 venturi models. Earlier 1-3/32 venturi models are still fairly available.

I have a bit less experience with the older Carter OE carbs, but the W-1s seem pretty bullet proof. The Carter WEs seem viable as an alternative, and I've used some of the fairly common 730s replacement carbs with pretty good results.