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Advice for rebuilding Carb


Chimi562
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Well I decided to rebuild my weber 32/36 carb and it's my first carb rebuild. Is there any advice you fellas can give someone like myself who has never rebuilt a carb before? What should I watch for? Should I be nervous? Appreciate the help and suggestions.

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Some suggestions:  

1.  Before dismantling, see if your accelerator pump is functioning properly (work accelerator linkage and look for a squirt of gas from the nozzle in the primary carb throat).  If it is, you don't need a new diaphragm.  If you do need 'em, O'Reilly sells just the diaphragm, not only as part of an overhaul kit.

2. buy one of those gallon cans of carb cleaner sold at auto parts stores (the kind with the small metal basket to hold all the bits & pieces).  An overnight swim in that cleaner and the carb will come out amazingly clean.

3.  When dismantling, take pictures/draw sketches of how things go back together.  Shake the float; if you don't hear sloshing, it's OK--not necessary to replace.

4.  You probably don't need a complete rebuild kit.  Jets rarely wear out, and you can make a top gasket from a sheet of gasket paper, using a hole punch and some sharp scissors.

5.  Keep all the jets for the two barrels separate from each other--you don't want to mix 'em up.

 

You'll find it's a lot easier than you thought; after you've done one, you won't fear a carburetor again.

 

happy tinkering

mike

 

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Check the play of the throttle shaft bearings. These tend to wear out and become a source of vacuum leaks. Bearing kits are available from Summit Racing.

Another part that is not typically included in a rebuilt kit is the power valve. The diaphragm in this valve tends to dry out and leak, also creating a vacuum leak.

If the carb has been sitting for a long time (dry), I would replace the plastic float.  Even though it still "floats", it could become soaked with fuel and sink....creating a tuning nightmare.

Don't for get to connect the idle cut-off solenoid  (next to the electric choke).

Take your time, take pictures or write down all the jets and seals that your remove.  Don't be ham fisted...these are delicate parts (brass and aluminum). 

 

John

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Here is one source for rebuild kits.

http://www.piercemanifolds.com/category_s/285.htm

 

A handy exploded view from the same site

http://www.piercemanifolds.com/category_s/322.htm

 

The bearings John refers to are plastic bushings, originally; but can be replaced with sealed ball bearings if you'd prefer.  Assuming that yours are worn / have side to side play. (Part 20 in the exploded diagram). 

 

If you do have to go that deep into it, the screws that hold the butterflies into the shafts have been staked in, so find a screw driver that fits them well and expect them to be tight.  

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I hate to be that guy. But if you factor your time into finding the parts installing them, tuning, fiddling etc..  You may want to get a new one.  I had gone down the road of rebuilding mine but found out that I had bent throttle shafts.  I strapped on a new one, and that fixed a whole bunch of stuff. 

 

I got mine from webberjets.com.  It is a knockoff but is identical and interchangeable with a Webber.  The throttle shafts are the bitch if they leak or are wobbly.  I got bearings to help solve that, although, with the bent throttle shafts in my original carb, I never used them. 

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Thanks to everyone for your advice. After diving into rebuilding the carb, it wasn't as scary as I originally thought. 

I got it all together but when I try to start the car, it dies right away. I tried to adjust the choke and that helped but it stayed at 3000 rpm. Should I be tinkering with the choke or should I just work with the idle mixture screw?

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11 hours ago, Chimi562 said:

Should I be tinkering with the choke or should I just work with the idle mixture screw?

 

Idle mixture needs to be set on a warmed up engine.  Butttttt... to get the engine warmed up, the choke has to be functioning properly.  There is a cold-idle adjustment screw to keep the revs down at a more reasonable 2000rpm.  It tucked in behind the choke dial and acts on the tiny cam mechanism.  I've found balancing the cold idle and choke plate requires only tiny adjustments to make everything work correctly.  The choke mechanism must be very clean to operate correctly, too. 

 

I meant to post this on your thread but never got around to locating it... a very good on-line tutorial

 

http://www.mk3supra.org/topic/561-guide-rebuilding-a-weber-3236-dgav-carb/

 

 

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4 hours ago, zinz said:

 

Idle mixture needs to be set on a warmed up engine.  Butttttt... to get the engine warmed up, the choke has to be functioning properly.  There is a cold-idle adjustment screw to keep the revs down at a more reasonable 2000rpm.  It tucked in behind the choke dial and acts on the tiny cam mechanism.  I've found balancing the cold idle and choke plate requires only tiny adjustments to make everything work correctly.  The choke mechanism must be very clean to operate correctly, too. 

 

I meant to post this on your thread but never got around to locating it... a very good on-line tutorial

 

http://www.mk3supra.org/topic/561-guide-rebuilding-a-weber-3236-dgav-carb/

 

 

I followed those steps which helped alot. I guess once I get home from work I'll double check everything.

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Don't forget the choke needs to be 'set' before you start by slowly flooring the gas pedal. When the choke is cold this works to close the choke plates at the top and advance a stepped cam on the throttle linkage to give a high idle speed. This could explain the difference between your symptoms of no start (choke not set) followed by 3,000 rpm (high idle, albeit probably over adjusted). Plenty of info on here with regard to adjusting the choke. 

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