tuning a carb

[gibson_es]

Slant 6 with a 1 bbl carb. I think its original, the PO said he recently had it rebuilt. He also told me it needed to be tuned.. any tips? For example, which screw is which?

When its in gear its very rough, very shaky. As if I was lifting up on the gas and then stomping on it over and over. It's better at around 60+ mph.... And its very hard to start.

Any ideas and advice would be great.

 

[67Dart273]

You're another guy who needs a shop manual, download one here:

http://www.forabodiesonly.com/mopar/showthread.php?t=132309&highlight=manual,+download

Unless there's something seriously wrong with the carb, like the float level way way too high, or the choke stuck closed, the carb does not normall cause "shaking," that's usually an igntion problem. I guess maybe if the idle was so lean, it might.

There are only a couple-three adjustment screws on the whole carb. Should be an obvious one acting on the mechanical linkage, for the "curb idle." May/ probably is another for the "fast idle" when the choke is in operation. The (normally) angled screw near the carb base is the idle mixture. Turn it out for rich, in for lean. Normally, start out 2-3 turns. Turn in until the engine starts to slow, and stumble, then out to smooth out. Smog cars run on the lean side of this setting. Make sure the car is UP TO temperature for this

There ARE some settings you need to check and sometimes adjust when cleaning the carb Usually right in the "carb kit" destructions. Such things as float level, "choke pull off" which is how far the choke butterfly opens when the little vaccuum pot actuates on start, and the linkage for the accelerator pump.

This is certainly one thing to check for "hard starting." Remove the air cleaner, look down the throat, engine off, choke open, and actuate the throttle. There should be a visible squirt of fuel from the accelerator pump when operating the throttle.

Hard to say, it may be getting "too much" or "too little" on startup, or fuel boiling on shutdown may be causing gas to flood over into the intake manifold.

Life ain't simple.

 

[gibson_es]

Actually. I have the manual. But its a serious PITA to use on a cell phone. My computer is down for a while.... Anyway thanks for the help... Now I need to figure out was IS Causing the shaking. Starting to think trans... However, you mentioned ignition, which I know nothing about.

 

[gibson_es]

You're another guy who needs a shop manual, download one here:

http://www.forabodiesonly.com/mopar/showthread.php?t=132309&highlight=manual,+download

Unless there's something seriously wrong with the carb, like the float level way way too high, or the choke stuck closed, the carb does not normall cause "shaking," that's usually an igntion problem. I guess maybe if the idle was so lean, it might.

There are only a couple-three adjustment screws on the whole carb. Should be an obvious one acting on the mechanical linkage, for the "curb idle." May/ probably is another for the "fast idle" when the choke is in operation. The (normally) angled screw near the carb base is the idle mixture. Turn it out for rich, in for lean. Normally, start out 2-3 turns. Turn in until the engine starts to slow, and stumble, then out to smooth out. Smog cars run on the lean side of this setting. Make sure the car is UP TO temperature for this

There ARE some settings you need to check and sometimes adjust when cleaning the carb Usually right in the "carb kit" destructions. Such things as float level, "choke pull off" which is how far the choke butterfly opens when the little vaccuum pot actuates on start, and the linkage for the accelerator pump.

This is certainly one thing to check for "hard starting." Remove the air cleaner, look down the throat, engine off, choke open, and actuate the throttle. There should be a visible squirt of fuel from the accelerator pump when operating the throttle.

Hard to say, it may be getting "too much" or "too little" on startup, or fuel boiling on shutdown may be causing gas to flood over into the intake manifold.

Life ain't simple.

Thanks for the tips. The majority of the shaking issues turned out to be plug wire #6 was not on its plug good....

I adjusted the screw for lean and rich. it was way to rich. I tuned it like oh said and I noticed a big difference in driving... I'm going to wait a few hours to let it cool down and see if its any easier to start. Thanks again!

 

[slantsixdan]

Welcome on the board. Tune-up parts and technique suggestions in this thread. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download. The engine will require periodic valve adjustment. And depending on your level of skill and experience working with old cars in general and your car in particular, you will want at least one (and probably all three) of the books described in this thread.