engine idles too fast?!?

[Anonymous]

when i turn on teh car the engine idles a very high speed, like if i was on the gas to bring up the res, also this occurs after short drives of less than a mile or two and when i put it in park or neutral...if i dont get the car to slow down on teh revs i also get very wicked backfires...what can this be...do i have to adjust something...i have very little mechanical experiance but would like to fix this problem....any help is appreciated...gary

 

[rbohm]

8) sounds like a vacuum leak to me. check that the carb is securely mounted.

 

[Anonymous]

i have checked my carb out a while ago and found i had a leak from the carb gasket...changed it out but still have the same problem...where else can i look for a leak???

 

[CobraSix]

Best way to check for vacuum leaks is to buy a can of carb cleaner. spray around the base of the carb and all over the carb one place at a time. When you spray a certain area listen to the engine RPMS. If they go up, that is where your leak is located.

Slade

 

[Anonymous]

thanks for the info...ill try that and see if i hear anything...

 

[mugsy]

Sounds like your high idle is too high!

The choke system, besides increasing the vaccuum in the venturi also opens up the throttle plate. If the choke coil pulls the choke off too slowly the car will idle high. So it could be either the choke coil needs to be backed off, or the high/fast idle needs to be knocked down.

Without knowing which exact carb you have there typically is a srew on one side, near the base. This controls the idle speed AFTER the engine/carb is warm. With the FoMoCo 1 bbls I have seen there is a lever that rests on a cam that opens the throttle plate when the choke is "on"; this controls the High Idle speed. To decrease the throttle opening that level has to GENTLY be bent.

You can either go out an fiddle around with the carb when it is cold to see how it works. You can open and close the choke plate with you finger to see how all the levers and cams work when the choke is on and off (again be gentle). Or the best bet is to buy a shop manual and it explains all the carb operations in there!