sbc stumbles and belches

So i have a 400 sbc with trick flow heads with a 274 comp cam and a unilite dizzy with mechanical advance,running 4x2 intake with 4 new 97's(not speedway)with progressive linkage,intake is wiaend staggerd.The car runs real good.The problem is when it's warm and i turn it off it stumbles and belches out the carbs.I checked the timing and at about 600 rpm i am about 8 degrees,i have moved the timing both ways and does nothing for it.I am also running a 1 wire alternator.Could i be getting feed back from this...

 

Sounds like its to lean and high cly. pressure. Try a richer idel mixture.

 

Backfires through the carbs or spits raw fuel out?

 

Try lowering the idle speed and advancing inital timing a couple of degrees.

 

It's not the alternator feedback/diode thing... when that's a problem it just doesn't turn off at all!

 

give this a quick look..it might help ya out..

 

thanks for all the info..

 

Did you syncoronize [sp] the primary carbs?

 

Yes i did..But i just now was thinking, it started doing this when i changed air breathers,could this be the culprit..I went to a different style of breathers..

 

thanks gunny.

 

when you say stumbles and belches do you mean when you shut down it runs on for a little then spits fuel out the carbs?

 

yes

 

ok i just had this problem .it was before i put a timing light on it .my timing was to retarded and cause this .i advanced my initial timing to 18 your cam wont need this much at idle but more than 8. whats your total timing at 3000 rpm should be 36 give or take a degree or two, at 8 degrees yor distibutor is adding 28?

 

Stumbles and belches? I'm sure quite a few HAMB members can relate to that. Seroiusly though, try a little more initial advance- 12 degrees or so, richening up the idle mix, and closing the throttle plates a little. Use a vacuum gauge connected to constant maniflold vacuum and set idle mix screws for highest vacuum. That, and more initial timing will let you have the correct idle speed and allow you to close the throttle plates via the idle speed screws. Having the throttle plates too far open at idle can make it want to run on.

 

Stumbles & belches?

You running it on alcohol?

...Oh Wait, that's me.