truck not running right

[james4499]

I have a 72 swb 350 it has a cam dont know what kind and it also has a holly carb it runs great at idle but when you put it in gear it stalls an sugestions would be great. it also an automatic, here is a pic of the motor if it helps

[Longhorn Man]

WHOLE lotta variables here
does it idle too low in park?
does it slam into gear killin the motor or soes it just not have the power to idle in gear?
Is it a huge cam?
Was the titming set by ear or properly?
What kinda tranny, does it have a lock up converter, and if so, how is it hooked up?
Has the carb been messed with?
Is this an all of a sudden problem... as in running fine yesterday, and this happened today... or has it been slowly sneaking up on you and then pow.... or did you just put the engine together and this is what you found?

[james4499]

ran and drove great now nada, yea its a big cam, it has a 350 tranny,idles at a decent speed normal, carb set by ear, not sure about timing

[straitnate14]

If it runs great in netural it might be somthing as simple as the idle stop screw. My question is have you hooked a vacume gauge to the motor at idle, you hook your gauge up and adjust your bleed screws to get as much vacume as you can until you stop getting improvments then you should be good, you should have a pretty steady reading on the vac gauge and should be around 15-20 less depending on how much cam you realy have

[69halfton]

sounds like most the truck is idleing too low. the more radical the cam, usually the higher the idle speed has to be.

Ive got a pretty serious cam in my 383 stroker. it idles anywhere from 950 - 1000 rpm in park (cold), but once you drop it into gear, it will fall to 650-700 rpm.


once warm it will drop to an even lower 500 rpm in gear. and about 850-900 rpm in park (warm)

[70rs/ss]

I'm guessing idle, slight possibility that it has a vacuum leak, or the timing may have moved a bit as well. If it was running and driving, I doubt the cam is the issue unless the idle speed has changed to coincide with the problem??

[Longhorn Man]

since it was doing fine, and then nothing, I suspect a blown vac advance on the dist.
Unplug the hose that goes to the dist, unplug the carb end of the hose... and suck on it.
If you get a real small bit of air and then nothing, I'm wrong.
If you get air like you are sucking on a straw... then you need a new vac can.

[70rs/ss]

Sweet idea LHM, I was not real confident in the vacuum leak cause it wouldn't want to idle but your idea makes sense!