sticking throttle on a Holley 670 cfm Avenger

tamanaco · #1 (**permalink**) 07-13-2008, 11:58 AM

Need some help...throttle is sticking about 1/4 open. It has triple return spring, cable linkage that is loose, no pedal sticking...so it is the carb. So what do I look for? It's four years old with 7000 miles mounted on an air-gap clone manifold with a Ford racing oval air cleaner. If you tap the throttle hard, it returns to normal operation.

Rick Parker · #2 (**permalink**) 07-13-2008, 02:57 PM

If the linkage is free, choke mechanism not catching, cable not frayed inside the outer cable(?) focus on the bores that the shafts pass through in the carb base plate. The return spring is best mounted to pull the linkage closed towards the front of the carb IE: inline with the cable that opens the throttle instead of from the bottom of the linkage towards the rear of the carb.
Also check the accelerator pump adjustment.

Buzz · #3 (**permalink**) 07-13-2008, 03:26 PM

Does it have an electric choke? That may be the source of the problem.

wtm442 · #4 (**permalink**) 07-13-2008, 03:49 PM

Remove the carb from the intake manifold and see if problem disappears. That will rule out throttle cable and/or throttle plates hitting bottom carb gasket or intake manifold.

Then with the carb off the car you can play around with abandon and not dump a ton of gas into the engine. Could be quite a few things holding the throttle open, but I know one thing ... its DANGEROUS to drive it.

Once its off the manifold, clean everything with carb cleaner and a small acid brush. Disconnect the choke assembly first. The problem could be with the choke, but more likely the throttle linkage/fast idle cam. Or as Rick said, the throttle shaft is worn and the throttle plates hanging up in the bores.

If you have had 3 throttle springs on it for a long time, a worn throttle shaft could be the problem.

I'm assuming that it sticks with the air cleaner removed. Sorry, but I've seen some strange problems on carbs.

jhv48 · #5 (**permalink**) 07-14-2008, 02:54 PM

Check the butterflys in the bores to make sure they are not sticking. Take the carb off and hold the carb up to the light with the throttle butterflys all the way closed. You should see light all around the butterfly. If not, then it is contacting the bore and could be sticking.

Also, as was said before, three springs could have caused the shaft to be worn and binding. Easy to rebuild.

Jerry Clayton · #6 (**permalink**) 07-14-2008, 04:44 PM

I've worked on a number of BDR cars that had a Lokar throttle cable setup and they had the cable core occasionally come out of the end piece which would then hold the carb about 1/4 open

Dennis Kelley · #7 (**permalink**) 07-14-2008, 09:50 PM

Check that the throttle is not hitting the air filter base also. I had this to happen and it was a stupid little thing but it made the linkage stick and you didn't notice it with the breather off. Good luck
later
dennis

tamanaco · #8 (**permalink**) 07-19-2008, 06:07 AM

Guys, thanks for all the input. Dangerous is right! An up date...I found the problem. It's my N2O WOT throttle switch. The wire linkage from the primary to the secondard shaft under the right vibration/slopping around situation, the end of this wire/linkage is catching the switch. The interesting thing is could not manually re-create this situation.