joshd

I have a weber carb on the 80 pickup I just purchased. The base plate was warpped, so I replaced that, but the p.o. must have turned up the idle, or the mixture to make up for the leak that was in the base plate. Truck runs smoother now, but when you hit the gas fast, it stumbles, and it idles really high. What is the proper way of adjusting a weber carb? Thanks in advance.

dcg9381

First, I'd recommend you buy a can of carb cleaner or engine degreaser and check for vac leaks.. It sounds like you still have one... Spray around the carb base, adapter, and any suspect vac hoses.

Adjustment details:
http://www.redlineweber.com/html/Tec...lean_best_.htm

joshd

Thanks for the reply. I will try that and see how it goes. As far as vaccum lines, all are new, and so is the manifold adapter, so I don't think that is the problem.

dcg9381

Doesn't matter.. Especially with the manifold adapter. If I recall right, they're cast pieces and pretty much suck..
Using new gaskets and properly torqued, I've seen them still leak...

joshd

Actually the adapter that I ordered is machined aluminum, their is two pieces though with three gaskets. Why they couldn't come up with a one piece adapter, I don't know. Seemed to seal up pretty good. I took the website listed in a previous post, and adjusted it to baseline readings, and it ran great. Air fuel screw was originally out almost 4 cranks and the idle screw was out 3 turns. Thanks for the info.

TOYZILLA

To Adjust The Weber While Running Set The Idle Screw "screw Next To The Throttle Linkage" I Beleive 750 Rpm Then Adjust The Mixer Screw Down " Screw In Front Of Carb" To Were The Idle Starts To Bog Down ,then Turn Back Out To Were The Idle Smooths . Or While None Running Turn Mixer Screw To The Right Till It Is Bottoms Out "not To Tight" Then Back Out Abought 2 & Half Turns That Will Get You In The Ball Park Then Adjust Like I Said At Top

joshd

Thanks Toyzilla, plain english, just like I like it. I will try that tonight to see if I can get it dialed in.

kyle_22r

it's been said already in here, the 2 piece adapters are cast aluminum and not even machined to my knowledge, so they're junk. there are 1 piece adapters out there but they're a little harder to find(i think trans-dapt makes them, look for a dealer and they *should* be able to order them). you can also get an offenhauser manifold with a weber flange pattern.

to properly adjust a weber carb you're going to need an assortment of jets. racetep.com or carbs.net can set you up, supposedly racetep can tailor a pack to your engine's configuration rather than getting a generic "4 cylinder" pack of jets. basically without an 02 sensor and gauge, you start with the idle jets. if you have to turn the idle screw more than 2 1/2 turns out, your idle jets are too lean, if less than 3/4 turns out, too rich. if it idles somewhere in betwee, you're good to go.

is the stumble happening when you kick open the secondary barrel, or just when you slap the pedal quickly? if it's happening when you give it a slap, it's probably the primary main jet, if it's when you kick open the other barrel it's likely the secondary main. however the way my engine is built, i've tried the largest jets i have in the secondary, and the largest accelerator pump jets and still get a bog even when it's hot. the solution for me was to use a double accelerator pump jet, kind of a trick part but it works for me

http://www.racetep.com/webjettune.html

titicaca

im having a bog issue with my weber 38. it seems to be rich on the main jets but im not sure. my carb has 2 idle jet screws, how are you supposed to set those? are they supposed to be set exactly the same?