Rochester B

[bloody hammer]

I recently rebuilt the Rochester B in my '62 Stepside (235) but it's still giving me trouble. At first it seemed to be "leaking" by fuel spilling over from the top. I assumed the float had dropped or some such so I rebuilt it with a kit from Mike's Carburetor (kit seemed good quality).

It runs great (better than before) but now it is leaking between the air horn and the bowl. From everything I've read I'm thinking one or both of the parts are warped. Some people have told me to double the gasket and see if that works. I'm also wondering if I can just put a little permatex or indian head stuff on the gasket and see if that makes a good seal.

Any advice or opinions?

[cortcomp]

gas will eat that stuff up, you can try the double gasket, but yes, you probably have warped parts (likely just airhorn side, you can clean it up on a flat belt sander.)

[68Gold/white]

Might try to adjust the float down a hair.

What's condition of float? Brass?

[bloody hammer]

Originally Posted by 68Gold/white

Might try to adjust the float down a hair.

What's condition of float? Brass?

new float, in great shape and brass.

One thing I think I did wrong was when I measured the the float height I didn't have the gasket on there. Seems a small difference though and I'm wondering if it actually matters?


I found some permatex at the store that specifically says is "fuel resistant"... but not sure if I should use it.

[68Gold/white]

Do not use the permatex...it won't do what you want it to, and just make a mess.

Gasket sometimes need to be in place. I'd lower the level, see what happens. Even lowering it a little too much shouldn't hurt. Seen the instructions on those carb kits? A boat load of different settings for different engines w/ essentially same type of carb...

[bloody hammer]

Ok, cool. I'm gonna skip the permatex for now and will only try it as a last ditch effort before giving up and buying a new carb.

i'm going to readjust the float and see how it goes. if it still leaks I'll try the double gasket (there's an extra one in the kit, although it is slightly different).

I'm appreciating your help, by the way.

[68gmsee]

Agree on the permatex. Don't use any type of gasket sealer on carb gaskets.

There's only a few ways fuel can come out of the top -needle valve installed wrong or defective or float adjustment. There is one other rare possibility. Fuel pump putting out too much pressure and forcing fuel out.

In the past I have flattened out slightly warped carb surfaces by lightly sanding with sandpaper laid out on a completely flat surface.

[66Submarine]

Originally Posted by 68gmsee

There is one other rare possibility. Fuel pump putting out too much pressure and forcing fuel out.

Doesn't seem to be rare at all anymore!

[bloody hammer]

re-adjusted the float to 1-9/32" with the gasket ON this time. Still wet between the air horn and bowl but now i'm thinking the leak is actually coming from the fuel line connector.

Also, I'm now noticing that if I rev it real good it spits fuel out the vent (black circle in photo).

[68gmsee]

Originally Posted by bloody hammer

....Also, I'm now noticing that if I rev it real good it spits fuel out the vent (black circle in photo)....

Fuel coming out of the butterfly shaft is a common problem. You can get bushings or kit to fix it. http://quadrajetparts.com/rochester-...aft-p-286.html

[bloody hammer]

Originally Posted by 68gmsee

Fuel coming out of the butterfly shaft is a common problem. You can get bushings or kit to fix it. http://quadrajetparts.com/rochester-...aft-p-286.html

Cool, I will look into this as well.

I really want to get this carburetor back in shape rather than buy a reman but I guess that's not a bad backup plan.

Any suggestions on who to buy one from?

[68gmsee]

Originally Posted by bloody hammer

......Any suggestions on who to buy one from?

The kit is not cheap. Unless you have more than one carb that needs repairing I would take it to a carb shop. There's a few shops in Austin that do carb work. Ask them if they do throttle shaft bushing repairs.

[bloody hammer]

Originally Posted by 68gmsee

The kit is not cheap. Unless you have more than one carb that needs repairing I would take it to a carb shop. There's a few shops in Austin that do carb work. Ask them if they do throttle shaft bushing repairs.

Ok, I'll call around town.

But as far as buying one "remanufactured".... any recommendations? I saw one at a good price on rockauto.com and even tried to order it but the order got all screwy and they ticked me off when I called to sort it out so I just canceled the whole thing.

[66Submarine]

As mentioned, the carb might also be flooding from excessive fuel pressure; go ahead and check it. It should only be 3 to 4.5PSI.

[bloody hammer]

Originally Posted by 66Submarine

As mentioned, the carb might also be flooding from excessive fuel pressure; go ahead and check it. It should only be 3 to 4.5PSI.

Ok, I see if I can pick up a tester. Can't imagine they cost too much and probably a good tool to have around.

[68Gold/white]

I have heard from a few about mechanical fuel pumps, having too much pressure. Problem might be that regardless of what brand, they are made in China.

I'd adjust it down another notch.

IF you get another carb, Keep your original. Factory rebuilt carbs usually have more problems, than solutions. It's hard to find an unmolested original anymore. Once you trade in the original, it's gone..........

Sometimes a needle/seat will bleed off, because of improper manufacturing. You can take a check ball slightly larger than the seat orifice, tap it into the seat, to make the seat is uniform. You have to make a judgement call on the size of the ball you have/or use, to make sure it will do the job

[bloody hammer]

I think I got it straightened out. I set the float lower and put a double gasket between the air horn and the bowl. It no longer leaks from the throttle shaft at the bottom or from between the air horn and bowl towards the top. I do not know WHICH of these things stopped the leaking... maybe both. Either way... there's no more leaking (for now).

[thelawdoc]

Originally Posted by bloody hammer

I think I got it straightened out. I set the float lower and put a double gasket between the air horn and the bowl. It no longer leaks from the throttle shaft at the bottom or from between the air horn and bowl towards the top. I do not know WHICH of these things stopped the leaking... maybe both. Either way... there's no more leaking (for now).

Bloody Hammer, how is your Roch B working out? I noticed that you got your rebuild kit from Mike's. I just ordered mine from him. He called me and gave me a lot of time on the phone as we ascertained the precise parts that my version of the B needs. He impressed me as knowing what he talks about. He advises against doubling the gasket because it puts something out of kilter -I don't recall his reason exactly. How did you remedy your leak at the throttle shaft? New Bushing? Or did you change the throttle shaft?

My Roch B seems to be an oddball. For one thing, it has stamping on it of "BC" which should mean that it has something other than manual choke. But all I have is manual choke. Then, whoever did the last rebuild of this carb put on a main gasket that did not have a hole where the carb has a hole. Also, the sintered bronze bearing was missing. Maybe all this is why I was getting bad mpg. We shall see. I have a stock 250. How is your mpg now?
-Alden

[bloody hammer]

Originally Posted by thelawdoc

Bloody Hammer, how is your Roch B working out? I noticed that you got your rebuild kit from Mike's. I just ordered mine from him. He called me and gave me a lot of time on the phone as we ascertained the precise parts that my version of the B needs. He impressed me as knowing what he talks about. He advises against doubling the gasket because it puts something out of kilter -I don't recall his reason exactly. How did you remedy your leak at the throttle shaft? New Bushing? Or did you change the throttle shaft?

My Roch B seems to be an oddball. For one thing, it has stamping on it of "BC" which should mean that it has something other than manual choke. But all I have is manual choke. Then, whoever did the last rebuild of this carb put on a main gasket that did not have a hole where the carb has a hole. Also, the sintered bronze bearing was missing. Maybe all this is why I was getting bad mpg. We shall see. I have a stock 250. How is your mpg now?
-Alden

Alden,

The throttle shaft stopped leaking after I adjusted the float down some. I think the problem was simply too much fuel.

I still have some leaking between the air horn and bowl but with the double gasket it's more of a slow seeping than full-on leak. I know it's not a good long term solution but for now I'm leaving it be.

That's odd that yours is stamped "BC" yet has the manual choke. Maybe someone pieced it together from different carbs?

There's something odd about mine as well... it's stamped with a "C" but as far as I know there is no such thing as a Rochester C (upper left corner). Is that the same place yours is stamped "BC"?

[66Submarine]

Yep.

[bloody hammer]

Originally Posted by 66Submarine

Yep.

That seems like an awful lot of dirt to me for no more than maybe 15 minutes total time of idling... and with a brand new inline filter too.

[66Submarine]

That rust like that is fine enough to get past those cheap filters; it's an awful flour-like powder, isn't it?

FWIW, I had good luck cleaning the tank in my current DD out with a chain.

[bloody hammer]

It is awful stuff and I'm really regretting that I filled the tank up a couple days ago... hahaaa. I thought about draining it but I think I'll just run it close to out and then start all the cleaning.

I'll try the chain thing. I was reading somewhere that a lot guys use muriatic acid and then baking soda to neutralize.

LMC has new tanks for about $150 but I've heard people say they are made of really thin metal.... so, not sure about going that route.

[68gmsee]

Originally Posted by bloody hammer

.....
LMC has new tanks for about $150 but I've heard people say they are made of really thin metal.... so, not sure about going that route.

I bought one from Spectra in Canada (GM49A) for my 68 about 6-7 yrs ago and was really pleased with it. Exact fit, like my original. They cost a little more but worth it if you're going that route.

If you decide to clean and/or replace drive it until you're almost empty and then get a cheap pump from Harbor Freight to completely empty it out. Buy a new rubber grommet and just use a razor blade to cut the old one out. It's also easier remove the front seat and pull it out passenger side.

[gmcdeadhead]

i bought one from rock auto, i am pleased with it, i sent back a used 2-barrel as a core so i can keep my original b carb, they accepted it , rock auto is the cheapest around i found , thanks.