im at a loss on his one

This might sound dumb, but do you have a manual (hand) throttle on it? I had a similar problem on my TJ where the outer housing on the cable had come loose sliding over the cable and with the leverage created caused the engine to rev as if the knob was pulled out.

Jim

 

i do not have a hand throtle, but thanks for the idea

 

This is indicative of a major vacuum leak. If you close the choke plate manually and the idle goes even higher that's a sure sign of a vacuum leak.

 

i cant seem to find it anywhere, its not at the base and its not at the two hoses ihave coming off the carb, where else could it be???

 

This issue is related to the throttle plates; I would do as others have already suggested; with engine off, look down deep inside
If you can't see them, then yank the carb off being very careful; something may have fallen thru and is jamming them from closing
if it has, you don't want it to fall down inside the manifold
turn the carb upside down so you can see better: WARNING: fuel will come out and the neddle/seat/float may stick, so be gentle

 

yes, but a major vac leak isn't going to let the idle speed go to 3000 rpm
...and run smoothly at that
most likely it would kill the engine; pull the hose at the base of the carb and engine will die right away; rpm's will not go sky high

yes the rpm's will increase with the choke plate partially closed, and maybe you can get to 3000 rpms before it chokes out the engine, but highly unlikely IMO

 

you guys are great! i do think that its in the throttle plate. i do have a hose in the back of the carb, but it was connected to my heater controller, i no longer have the old type controller so i just plugged the hose. i have checked all vacuum hoses by pinching them closed and nothing changes, also i did spray the bottom of the carb with caqrb cleaner and no bublles or anything coming out, like i said i put a new gasket on right away. i have no way of checking the timing cause it runs to fast to check. i will look at the throttle plate thing tonight, i bet thats it. i think you guy are right about the 500cfm carb, i think i will just get the rebuild ki for the holly 390 thats on tehre

 

Just for future reference- when you spray the carb cleaner at all possible points of vacuum leaks, you won't see any bubbles, but you will hear the engine speed change if there is a leak.

If the timing was to far advanced, it shouldn't speed the engine up that much, and it would also buck the started while it was being cranked.

 

Maybe only one spring on the advance fly weights broke and it's advances too fast?

 

ok whats this advance fly weight stuff??

 

Another source for vacuum leaks is the intake manifold gasket where it bolts to the heads. Usually though, if it leaks from the bottom side, your engine will smoke due to pulling oil into the intake ports.

 

i have actually had one of the throttle plates come slightly loose from the shaft that they are attached to. make sure that if there are any small screws that hold the actual plate to the shaft in the throat are tight or that the plate is solidly attached/closed. it may be that they are just loose enough to create a gap or leak between the plate and the wall of the throat. when the engine is off it may look ok. but when the engine is running the vacuum from below actually sucks the plate down or in a little to imitate cracking the throttle.

don't look into the carb while the engine is running. (you probably want to keep your eye sight and eye brows in case of a backfire)
or the return spring may weak enough that it doesn't hold the plate closed when the vacuum forms. ( i think this last one was suggested before?)

oh yeah and this last one always works for me. first you gotta find a kosher chicken, some salt and a long heavy string......

 

thans again guys for all the great advice, i did not get out of work till real late last night so no dice on checking all this out. first thing i wll check is the throttle plate, if that doesnt work then i will check this dist. my hei cape conversions dist should be in today ( thanks mruta) so might try and put that in as well

 

well, it is not the throttle plate, or atleast i dont think it is. i looked donin there last night, and when i move the throttle linkage, the plate opens and shuts. are the back plates supposed to open and shut as well, cause i noticed that they dont. but come to think of it, i dont think i have ever seen them move (not even sure if they are supposed to. my hei came last night, adn i bought a carb rebuild kit last night, so i think tonght if i have time i will rebuild the carb and install the new dist and see hwere that leads. i just really wish i could figure this out, im running pretty rich right now just to keep the rpm down around 1500-1700