holley 1920 ideling too high

[desy500]

Hi Guys , after rebuilding 2 holley 1920's I can't get the idle lower then 1000 or so ,She starts right up on warm days ( no chokes ) and is running stronger then before the rebuilds. I have backed out the curb idle screws till they are not touching the carb at all , and it won't go lower then 1000, I have read some info that it could be a vacuum leak , power brake ect..

I am looking for a good place to start - it is the offy 2 carb set up on a 225 .40 over with mild cam , and headers

 

[mopar_nocar]

Carburetor linkage?

 

[Killer6]

Dude, did You get rid of the binding? Is this the case w/the linkages disconnected as^^^^? Unless the linkages are totally free throughout their entire travel, and the
adjustment doesn't bind at the pedal i.e. pedal pivot, etc.... then that would need to be corrected 1st.
Second, how do the throttles compare visually both off the screws w/the linkage off? There is a chance the throttle You had apart is not centered in the body, and is
not closing completely? Besides the fuels ability to leak out of the shaft, is there play & poss. vacuum leakage a well? If I remember the throttle blades have a small
hole drilled in them, acceptable when using 1 carb, but You may have to close them up using 2 w/a small cam.

 

[TXDart]

Sounds like a vacuum leak.
Try cupping your hands over carbs to see if you can lower idle....you could also put a vacuum gauge on it and report back what it is pulling ...
Does either carb respond to turning in the a/f ratio screw...
Spray some carb cleaner at base gasket or throttle shafts to find leaks....careful around checking intake gasket...exhaust can ignite the carb cleaner...need vacuun reading first....

 

[desy500]

Dude, did You get rid of the binding? Is this the case w/the linkages disconnected as^^^^? Unless the linkages are totally free throughout their entire travel, and the
adjustment doesn't bind at the pedal i.e. pedal pivot, etc.... then that would need to be corrected 1st.
Second, how do the throttles compare visually both off the screws w/the linkage off? There is a chance the throttle You had apart is not centered in the body, and is
not closing completely? Besides the fuels ability to leak out of the shaft, is there play & poss. vacuum leakage a well? If I remember the throttle blades have a small
hole drilled in them, acceptable when using 1 carb, but You may have to close them up using 2 w/a small cam.

Yes they do have the small hole in the blades , I believe they are centered in the body ,but will take the carbs back off and recheck everything if the easier trouble shooting comes up nil. Have been working , so I will get to it Sat. I can stall the engine if I hold my hand over the carb. I will start with the linkage.

 

[desy500]

Sounds like a vacuum leak.
Try cupping your hands over carbs to see if you can lower idle....you could also put a vacuum gauge on it and report back what it is pulling ...
Does either carb respond to turning in the a/f ratio screw...
Spray some carb cleaner at base gasket or throttle shafts to find leaks....careful around checking intake gasket...exhaust can ignite the carb cleaner...need vacuun reading first....

got some time today to work on her , yes she will stall if I put my figures over either carb , vacuum is around 17 - 18 on both of them , with the screw out 1 1/2 turns on both . My meter is brand new ( innova 3340 ) but I think it is off , or I am? it reads 900 - 1100 nothing steady , so I hooked up an old PRO Tach I had laying around and it reads 650 - 800 again nothing steady.

So I have 2 question for you guys ( please know that I am new at doing anything more then basic tune ups , brakes ect.. ) if I back off the curb idle screw all the way on both carbs shouldn't it stall ? It doesn't , and I don't see the linkage causing it ? And is the cam making the idle jump a little ? I did check all around the base of the carbs with cleaner , and engine stayed the same , if I shot a squirt in either carb , she stalled . And turning the A/F screws in a full turn on either carb will stall , but with the vacuum gage hooked up it didn't change a whole lot when I opened them up and extra full turn to like 2 1/2. It probable changed maybe 2 points at most from 1 full turn to 2 1/2. Did take it out on the road for a couple miles , ran pretty good then it started to drizzle so I put her back inside , when she cools off I'm going out to play with it some more.

 

[desy500]

Dude, did You get rid of the binding? Is this the case w/the linkages disconnected as^^^^? Unless the linkages are totally free throughout their entire travel, and the
adjustment doesn't bind at the pedal i.e. pedal pivot, etc.... then that would need to be corrected 1st.
Second, how do the throttles compare visually both off the screws w/the linkage off? There is a chance the throttle You had apart is not centered in the body, and is
not closing completely? Besides the fuels ability to leak out of the shaft, is there play & poss. vacuum leakage a well? If I remember the throttle blades have a small
hole drilled in them, acceptable when using 1 carb, but You may have to close them up using 2 w/a small cam.

 

[desy500]

The only thing I had changed from the way the linkage was - the little 2 inch piece that has a tiny cotter pin holding to the plastic arm for the accelerator pump was in the first of the three holes on the other end of it. I read in the shop manual that it belonged in the middle hole , so I changed them to the middle hole. Today I changed them back to the first hole , and I think that cleaned it up. both throttles appear to be even. Check my other reply above for more of what I did. And thanks again for hanging with me as I try to learn this!

 

[Killer6]

View attachment 1715045182 The only thing I had changed from the way the linkage was - the little 2 inch piece that has a tiny cotter pin holding to the plastic arm for the accelerator pump was in the first of the three holes on the other end of it. I read in the shop manual that it belonged in the middle hole , so I changed them to the middle hole. Today I changed them back to the first hole , and I think that cleaned it up. both throttles appear to be even. Check my other reply above for more of what I did. And thanks again for hanging with me as I try to learn this!

The carb I have is in the middle hole on that link arm, but if both of Yours were in the first, then they should stay there. Moving the link further out to the middle & end holes
will allow an increase in pump stroke, but the link might need to be adjusted by bending it to take advantage of that. The pump should have plenty of travel that wouldn't be
holding the throttles open just switching holes, there's plenty of leeway, so unless the little links are binding somehow..............................