Carb sticking?

[69importkilla]

So I running a new Holley double pumper. When I first start the car it idles at 800. After driving it for a few and for example, rolling up to a stop sign the car is at 1000 - 1100 RPM. A quick tap of the gas pedal brings the engine back to the correct speed. I have a brand new Lokar throttle pedal assembly and cable.

Side note, by friends OLDS does the same thing with similar equipment....

[Chevelle598bb]

Are you running a throttle return spring? It may not have enough tension to close the throttle blades.

[BCHALK22]

x2 also maybe a bit stronger of a spring.

[69importkilla]

I am running the dual spring set-up from Lokar, shouldnt that be enough?

[Chevelle598bb]

Should be as long as it is installed correctly. Do you have any pictures of your set up. Does the throttle stick with the air cleaner off?

[dontlifttoshift]

Possible causes that I have seen make sure the carb itself moves freely......Is the carpet in the way of the pedal or cable.....any tight bends in the cable housing.......Misalignment where the cable goes through the firewall and attaches to the pedal....not enough slack in the cable, example cable length was set with the choke engaged and on the fast idle cam......I have also seen an improperly set choke come on during cooler weather drving, probably not the case here.

That's all I got right now.

[69importkilla]

Im working on the car right now, I'll let you guys know...

[69importkilla]

So I pulled the air cleaner off and I still have the same trouble. No carpeting around the gas pedal and I loosened up the cable a bit...any other thoughts?

[Chevelle598bb]

Are you running a 4 hole carb gasket? Maybe it is too small for the throttle blades to clear?

[Chevelle598bb]

I would also pull the carb to see if the throttle linkage works smoothly and returns to closed position.

[dontlifttoshift]

Disconnect the cable from the carb at the ball socket, it should snap right off. See if you can't manually get it to stay at the higher rpm. That will eliminate the cable and pedal from the equation. If that works make sure the preload on the pedal isn't too tight.

[TheJDMan]

While you have the cable disconnected from the carb, cycle the cable and pedal and feel for any binding or tight spots in the travel.

One other thing that can effect idle speed is the mechanical timing advance curve in the dist. I had a situation with Dust Off where I set the idle speed to 900rpm and it would stay there but pulling up to a traffic light the idle wanted to settle around 1300 rpm. If I just allowed the clutch to drag the engine rpm down it would idle at 900. I finally determined that the mechanical advance was coming in at around 1000rpm causing the higher idle until I would physically slow the engine and retard the timing. I installed a slightly stronger advance spring and the problem went away.

[69importkilla]

I seperated the cable from the carb and the issue still exsists. The gasket is of an open design, not the 4 hole type.

With regards to timing advance, the engine is distrubtorless, I dont want to say for sure, but I think Steve's suggestion doesnt apply...

I was starting to think maybe the carb isnt sitting flat and when tightened down, it is distorting the base a little?

[dontlifttoshift]

Loosen the 4 bolts holding slightly and see if it is better. If it is better then you know what the problem is.

[Orange71]

2 years ago I bought a new Holley 650DP HP Street. While adjusting the accellerator pump linkage with the carb off the engine and upside down I noticed that the throttle blades (mostly the secondary) would hang open. Touch the linkage and it would snap closed. Not good I said so I sent it back (Summit) and they sent me another one. It did the same thing. These have the standard cast baseplates. I didn't see any binding but it sure seemed tight and there was some noise from the throttle shaft area. Sent that one back and called ProSystems.
Might be worth taking the thing off and check for that.

[Shaker455]

This carb have a choke?

If it does the fast idle cam may need to be adjusted

[69importkilla]

It does have a manual choke, but if its not on the choke why would the fast idle cam need to be adjusted?