my truck hates me,carb problem ?

[chainsaw]

Finished my engine swap, ran fine for two days, now wont stay running. 350 with big cam, 750 double pumper, hei , dont know anyother specs on engine. Acts like its flooding, have to hold it to the floor to start, sputters then cleans out and runs smooth for about a minute then sputters and dies.If you keep the revs steady at about 3 k, same thing runs smooth then sputters and dies. It looks like gas is dripping in the primaries when engine is off. Is that my problem? I'm NOT an engine guy,I did paint and body back in the day so I dont have any tuning tools or skills other then a timing light. It would start at the touch of the key without giving it any gas yesterday. Sorry for rambiling on.

[brokenspoke]

75% of carb problems are electrical....

[chainsaw]

That was my next question, carb or electrical ? Would a bad voltage regulator cause the same symptoms?

[TopFuel1966]

Originally Posted by chainsaw

That was my next question, carb or electrical ? Would a bad voltage regulator cause the same symptoms?

If you can see gas running down the throttle plates with the motor off i think you can rule out the voltage regulator and focus on the carburator in general and start with the float level in particular.

[fryer1979]

Originally Posted by TopFuel1966

If you can see gas running down the throttle plates with the motor off i think you can rule out the voltage regulator and focus on the carburator in general and start with the float level in particular.

Floats and needle/seats would be my guess, although a 750 double pumper is a lot of carb for a 350.....

[wildearp]

Pull out the sight plugs one at a time on each bowl and adjust your float level until fuel is even with the hole. If it leaks after that, you are gonna need new float seats.

A 750 is just fine on a 350 that is breathing very well.

If it is a heat/percolation issue, you need to add a non-conductive spacer under the carb, preferably phenolic or plastic.

[chainsaw]

I went out this morning and it fired right up like nothing was ever wrong. No signs of gas dripping in the primaries like last night. The float level seams low, not upto the bottom of the sight plug, havent tried to adjust it yet. It has about a 3'' alum. spacer under the carb. I still dont trust it yet, like I said this truck hates me but I havent givenup on it yet.

[TopFuel1966]

Could be that some dirt or other foreign object got caught in the needle and seat and has since passed through. That 750 double pumper is a pretty big carb for a 350 unless you've done some cylinder head work to it.

[Rannos]

Sounds to me either trash in the needle and seat or clogged air bleeds will do the same. If it does it again remove your air cleaner. hold your hand covering the primaries and pop the throttle from idle to full open as fast as you can while the truck is running. Do this 2 or 3 times letting your hand off after it revs up and if it clears up its trash in the air bleeds. Remove them spray a lil carb cleaner in them and let sit for a minute then blow out with compressed air and re-install. Hope this helps.

[wildearp]

To clean your needle seats and orifices:

Turn in the needles clockwise and count the turns carefully. Write this down. Remove the needles. Put the long nozzle on your brake cleaner spray can and hose out the carb a touch on each needle hole. This is a good trick to do periodically.