63 c-10 1bbl carb question

[1963c-10]

Ok, truck full of gas, fuel pump working, fuel filter clean. Truck will only run with choke cable pulled all the way out. Carb is Rochester model B which was rebuilt by Holley 6mo ago. My guess is trash in the carb, but wanted a couple of opinions before I start tearing into it. Engine runs smooth with the choke out and cuts off if choke in. Engine was ideling fine and truck has been running great and then just cut off (luckily in the drive). If trash in the carb...what part of carb would it most likely be in?

[1963c-10]

Also....vacuum lines good. With choke pulled out gauge shows 10, normally around 3-4 with choke off on dash guage.

[Gianyveedub]

Does it do this when the engine is warmed up? If so, check for vacuum leaks. If it does it when its cold it might be like the problem I finally solved, in which the engine had to be warm up to operating temp. My truck would start fine and idle with the choke out, but the moment I pushed it in, it would slow down and die. or if I gave it gas, it would backfire and die. I hope this helps some.

[1963c-10]

Does it either way. Cold or at operating temp

[cb1965]

idle screw? when ive had issues with my carb( not a 1bbl ) i get it to operating temp and start messing with idle screw and throttle, test drive and repeat untill i feel the engine run good.. good luck
ps. check timing.... might have an effect but not sure...

[maxwoof]

Check all ignition sources first -timing, etc. They show up sometimes in strange ways that are often mistaken for the carburetor.

Manifold vacuum (below the throttle plate) should be highest at idle - definitely more tha 3-4 inches, which makes me think you have a leak somewhere. Check carb joints, carb base, intake manifold, distributor line, etc. Also, throttle shafts tend to wear the bores and leak. Could also be a valve issue. Could also be a defective rebuild, or dirt in the carb somehow. Could be as simple as the air screw.

[1963c-10]

Took the carb off last night and disassembled. Everything looks good there. I plan to check for intake manifold leak tonight. And I want to run it off a different fuel source just to rule out bad fuel. Pertronix was installed 2 weeks ago, timing seems good. Runs like a champ with the choke out, put the choke in and it just shuts off. Damnest thing....Plan to contact Holley this a.m. just to see what they suggest also. Carb was installed this past June.

[1963c-10]

Talked with Holley this a.m. They think that its either trash in the mixture passage or intake manifold gasket has a leak somewhere. Guess I'll do the carb cleaner trick tonight to check manifold gasket and repull carb to double check passages.

[Gianyveedub]

If you have a propane torch, open the vlave on it while the truck it running and place it near the intake openings and carb base. If the idle increases, then you know you have a leak.

[1963c-10]

No propane, but I have aerosol hairspary (my girlfriend donated it) and carb cleaner

[1963c-10]

Well, with 60mph wind gusts and heavy downpour, was unable to go out and do check for intake leak. Tried, but unable to hear any rpm drop. Have to choke her hard, so I dont know if I'd be able to hear it anyway. My plan is to change the intake gasket this weekend anyway, reclean carb, replace fuel filters, check spark plugs and pray for the best. Any other opinions would be great.

[1963c-10]

ok, well cant seem to find an intake leak, but theres alot of small places that I cant get into to check. My plan of attack is to take the carb off again 1st, clean again...check idle and mixture screws again, and if problem persists...then I go to intake/exhaust gasket.

[Gianyveedub]

Before that, check your PCV valve. I know my truck ran like ....poop... when the PCV gasket was bad and was letting the truck run lean and all it would do is stumble and die.

[1963c-10]

Okay thanks.

[1963c-10]

Ok, changed out exhaust /intake gasket (of course I couldnt help myself to clean and repaint intake), replaced fuel pump (under warrenty), new fuel/vac lines, installed a fuel pressure guage (holds 4psi), and took off carb -recleaned, new gaskets, new pcv valve and line, fuel & air filter. Plugs are clean, fuel tank full, and checked strainer in tank, clean as a whistle. Fuel flows good, just wont run unless choke is closed on carb. Need help. Still having same problem...only runs with choke cable pulled out. Any help be appreciated.

[Gianyveedub]

Have you done a idle mixture adjustment. I know with my dad's truck, it had similar problems. I hooked up a vacuum gauge and adjusted the mixture till it was at a steady vacuum, then I adjusted his timing until I reached the max vaccum and it solved his issue. It's worth a shot.

[1963c-10]

Waiting on Napa rebuild kit that ordered yesterday. Be here tonight, so be out in the 40degree weather pulling carb and rebuilding. Gota love it.

[1963c-10]

Ok, got her running again. The little tube behind the main metering jet which is pressed in by the factory fell out

[Gianyveedub]

Glad to hear you got her running, nice work man.

[X24]

You the man.
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[1963c-10]

Thanks....was a real pain in the *$$ to figure it out. The tube is pressed in at the Holley. They just had carb about 6mo ago, but I will say its the 1st time Ive ever encountered this problem with the Rochester Model B. They have been very reliable carbs since getting my 1st 63 at the age of 16.