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07-26-2014, 11:18 PM | #1 |
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Rochester B
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? |
07-27-2014, 09:28 AM | #2 |
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Re: Rochester B
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.)
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07-27-2014, 12:44 PM | #3 |
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Re: Rochester B
Might try to adjust the float down a hair.
What's condition of float? Brass? |
07-27-2014, 01:46 PM | #4 | |
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Re: Rochester B
Quote:
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. |
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07-27-2014, 01:57 PM | #5 |
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Re: Rochester B
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... |
07-27-2014, 02:06 PM | #6 |
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Re: Rochester B
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. |
07-27-2014, 03:19 PM | #7 |
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Re: Rochester B
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.
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07-27-2014, 06:40 PM | #8 |
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Re: Rochester B
Doesn't seem to be rare at all anymore!
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07-27-2014, 04:52 PM | #9 |
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Re: Rochester B
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). Last edited by bloody hammer; 07-27-2014 at 04:54 PM. Reason: photo |
07-27-2014, 07:57 PM | #10 | |
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Re: Rochester B
Quote:
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68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive... |
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07-27-2014, 11:49 PM | #11 | |
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Re: Rochester B
Quote:
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? |
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07-28-2014, 09:23 AM | #12 |
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Re: Rochester B
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.
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68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive... |
07-28-2014, 10:58 AM | #13 | |
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Re: Rochester B
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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. |
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07-27-2014, 06:37 PM | #14 |
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Re: Rochester B
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.
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07-27-2014, 11:46 PM | #15 |
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Re: Rochester B
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07-27-2014, 07:48 PM | #16 |
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Re: Rochester B
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 |
07-30-2014, 09:39 PM | #17 |
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Re: Rochester B
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).
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08-16-2014, 04:55 PM | #18 | |
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Re: Rochester B
Quote:
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 |
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08-17-2014, 02:01 PM | #19 | |
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Re: Rochester B
Quote:
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"? |
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07-30-2014, 09:50 PM | #21 |
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Re: Rochester B
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07-30-2014, 10:03 PM | #22 |
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Re: Rochester B
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. |
07-30-2014, 10:45 PM | #23 |
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Re: Rochester B
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. |
07-30-2014, 11:07 PM | #24 | |
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Re: Rochester B
Quote:
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.
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68 GMC 250/3 speed Saginaw p/b p/s 69 Chevy 350/350 currently in pieces still lookin for a cab 06 Trailblazer I just want a vehicle that I can work on, that won't talk to me, leave error msgs or keep track of how I drive... |
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07-31-2014, 03:16 AM | #25 |
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Re: Rochester B
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.
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