engine and drivetrain Quick question for the carb guys

[Byron]

Cleaned up the carb and replaced the gasket tonight. I'm trying to get my manual choke all set. Gas to floor, pull choke lever, and the flaps close up (as I understand they should). When I start up, it idles like a tractor.....low enough that the alternator charge light is on. Without the choke.....it idles higher, but still low and rough. So, apparently I don't understand how the choke really works. Also, it wants to backfire through the carb, and spray some fuel. Any thoughts?

Setup: Weber 32/36, stock engine (76), pertronix, bosch blue coil

Is this an obvious adjustment issue that I'm missing?

Thanks!!!

[nbristow01]

My be too warm for a choke. Electric chokes usually have a fast idle cam. Not sure on manual. How does it run one warmed up?

[Byron]

Runs fine once warm, but I feel like it's not tuned well.....or maybe low compression....or.....??

[Kidasters]

So - what the choke does is make the mixture rich for when the car is cold, by restricting the amount of air that can come in. Which is why the butterflies are closed.

Sounds like fuel delivery problem. I'm betting you need to make some choke adjustments.

Either that - or your timing is way off, or you have the plugs hooked up to the distributor wrong. Backfiring through the carb is bad.

I bought a pretty good book from Pierce manifolds on tuning carbs. I'll look for it to see what it says.

Ken

[Byron]

Cool, thanks. I looked over it. I will tackle tomorrow, and see where I get.

Thanks for the link!!

[02Les]

My Touring is like that.

Will not idle when cold - it started doing this suddenly; have to sit with my foot on the accel pedal until it's warm then it's ok.

Had a water choke carb, changed for an electric choke carb, and finally bought a new manual choke carb. No change.

Methinks it's not the carb!!

[02for2]

When you say '"cleaned up the carb", I'm getting the impression that you didn't actually rebuild it. Maybe just shot carb cleaner through the barrels or cleaned the exterior, is that right?

If so, you may have actually worked some varnish loose which is now partially blocking some of the small orifices in the carb (jets, air correction, emulsifier tubes, etc.).

If you did rebuild the carb, how long did you let the parts soak? I always go 48 hrs. soak time because I've seen several rebuilds with less than this only partially dissolve the varnish and parafins which naturally buildup over time. Once some of this material is loose, it's easy for it to migrate to the minute orifices described above and partially clog them.

In fact, since they're cheap, I always use fresh jets when doing a rebuild. Later, I clean the old ones thoroughly in an ultra-sonic cleaner a friend has, and shelve them, in ziplocks, for future rebuilds.

There isn't a whole lot to setting up a manual choke. Adjust the cable so that when the choke knob is pulled, the butterflies close completely (but only completely), and when pushed back in the butterflies open completely. Too much adjustment and you risk twisting or bending the throttle shafts, and then you're in trouble.

I have some ideas of what may have happened, but need a better description from you re. 'cleaned up' before I can narrow it down.

Cheers!

[Guest Anonymous]

My be too warm for a choke. Electric chokes usually have a fast idle cam. Not sure on manual. How does it run one warmed up?

Man. Deep. Raised on carbs.

[TobyB]

2 things happen when you pull a 32/36 choke.

It closes the strangler ('choke') plate to richen the mixture, and

opens the throttle plate to let in more mixture.

If everything else is OK, (float level set, bowl clean, etc)

you can add more throttle opening. There's a screw- and it's

a booger to find. It DOES wear, so it's not all that unusual for

a well- used carb to need some adjustment. One thing I've found

is that it will wear a flat onto itself- you'll make your life a lot

easier if you take it out and dress it flat on the end if you end up

needing to play with it. It's hard to see but easy to find

if you get a friend to pull and release the choke while you look

at the linkage. I never remember where it is, since it only needs to

be fussed with very occasionally.

On a properly adjusted choke, cold, the right amount of choke

will only raise rpms by a hundred or 2. As the car warms,

revs should rise- until you push the choke back in (or the bimetal

takes choke off).

hth,

t

[Byron]

Correct, I didn't rebuild, just cleaned with some carb cleaner. It didn't seem too gunky or varnished.....but my definition may be different than another's.

Thanks!