33 replies to this topic

[Pollarized]

Hi all, after some help.

Car is LJ with 173 with xu1 style headers and exhaust, electronic ignition and 4 speed with 3.55 gears

 

Recently bought a second hand 350 holley on cain manifold, which i bolted straight on to see where it was at and ran really well. After a short drive was impressed enough to go ahead with a proper install.

 

Converted accelerator to cable, pulled holley apart for a cleanout, new gaskets and slight change in jets. (only 2 sizes)

 

Bolted all back together and runs ridiculously rich at idle, sounds like it has a funny car cam, belches black smoke, mixture screws do nothing and destroys spark plugs in no time flat. Get it past the idle stage clear its throat and runs well. Last time i removed it there was a pool of fuel sitting in the manifold below where the carby sits.

Also bolted the carb to another motor (289) and very similar results, so i know the problem is in the carby.

 

Have checked all the usuals, float level is fine, power valve not damaged (replaced anyway) and can not see any fuel coming from nozzles when looking in running car. Have checked the carb body and base plate for warpage but all seem good.

 

I am assuming there is maybe some sort of blockage in the idle circuit caused by me when going through it with carb cleaner but i can't get my head around how it works and what could be causing this. Would love to hear some ideas if anybody has any.

 

Sorry for the long post, Gary

[rodomo]

Float level is fine = ?

[Pollarized]

Float level is fine = ?

Yes rodomo, when site plug is removed and rock the car a little fuel seeps out

[rodomo]

What about when it's running? Float level should be set running.

[Pollarized]

Sorry, should have said running. Sits just under site plug when running.

[Lima31]

Idle screws should be all the way in then backed out 1-1.5 turns. If you wind them all in and the motor still runs, then you have a fuel leak from that circuit (blocked screw?) or somewhere else.

[Pollarized]

Lee, idle screws are doing not much at all. Prior to my cleaning they responded well. I also assumed a leak from that circuit but have cleaned through all passages that i can get to. 

[Lima31]

This page might help then

 

https://www.carburet...base/2300-idle/

Edited by Lima31, 14 January 2022 - 10:57 AM.

[axistr]

Incorrect gaskets or gasket fitted incorrectly is a possibility. Double check for vacuum leak. 

[Pollarized]

Incorrect gaskets or gasket fitted incorrectly is a possibility. Double check for vacuum leak. 

Double checked gaskets, even tried putting the old ones back in just in case.

[S pack]

Did you alter the idle speed screw setting?

[Lima31]

I still think there is an issue with the idle circuit, or something else is pissing fuel in somewhere

 

Set the throttle blade correctly?  Take the carb off, and look at the amount of gap showing at the idle ports

[ozyozyozy]

If the float level is ok.
Possible thought.
You say the idle screws do nothing. Can check with engine off, when looking in carb the throttle blades should be near closed, there may be a small transfer slot(4 barels have this), should be able to see a small amount of it, if not the blades are open too much and engine is not running in the idle mixture circuit.
Not enough intial timing can cause people to run the throttle blades open too far and lead to this.

[S pack]

If the float level is ok.
Possible thought.
You say the idle screws do nothing. Can check with engine off, when looking in carb the throttle blades should be near closed, there may be a small transfer slot(4 barels have this), should be able to see a small amount of it, if not the blades are open too much and engine is not running in the idle mixture circuit.
Not enough intial timing can cause people to run the throttle blades open too far and lead to this.

Exactly, if idle speed screw is holding the throttle discs/blades/butterflies open too far then fuel will be drawn from the transition slot effectively bypassing the idle circuit.

 

[axistr]

Has it got a ball bearing check valve in the accelerator pump circuit. ? Sounds like fuel is being sucked out under the throttle blades effecting the idle circuit.

[Pollarized]

Thanks for the replys

I still think there is an issue with the idle circuit, or something else is pissing fuel in somewhere

 

Set the throttle blade correctly?  Take the carb off, and look at the amount of gap showing at the idle ports

Yes, have started off with the blades closed and opened gradually from there with no better results

 

If the float level is ok.
Possible thought.
You say the idle screws do nothing. Can check with engine off, when looking in carb the throttle blades should be near closed, there may be a small transfer slot(4 barels have this), should be able to see a small amount of it, if not the blades are open too much and engine is not running in the idle mixture circuit.
Not enough intial timing can cause people to run the throttle blades open too far and lead to this.

 

Double checked timing but also swapped the carb to anothere engine whith same results, also tried the ford 2 barrel on the 173 and ran really well which brings me back to definately the carby.

Has it got a ball bearing check valve in the accelerator pump circuit. ? Sounds like fuel is being sucked out under the throttle blades effecting the idle circuit.

Have not checked the accelerator pump as i had never opened it from the start but will check.

I think your second line is exactly the issue, i see nothing entering above the blades but there is a lot of fuel entering from below the blades.

[I'm a Red Motor fiend]

So you have a Weber but want to put the Holley on why?

[S pack]

I think your second line is exactly the issue, i see nothing entering above the blades but there is a lot of fuel entering from below the blades.

The only orifice situated below the throttle discs that fuel can discharge from is the idle circuit, which the idle mixture screws control the rate of flow.

[73SUNBURSTEXYOUWON]

Hopefully this may offer some assistance, from holley,
Taking note of fuel pump pressure too.

https://youtu.be/ge-mIk6nEYQ

https://youtu.be/8LN...53239D6A7D7BFF0

https://www.google.c...h2rA5YDQfcCTfzx

[Pollarized]

So you have a Weber but want to put the Holley on why?

Nope, don't have a weber

The only orifice situated below the throttle discs that fuel can discharge from is the idle circuit, which the idle mixture screws control the rate of flow.

Correct, except my mixture screws are doing nothing

[S pack]

Nope, don't have a weber

Correct, except my mixture screws are doing nothing

Which means the fuel must be coming from a passage/s or orifice/s which is/are above the throttle discs if the mixture screws are wound right in.
 

Edited by S pack, 15 January 2022 - 03:48 PM.

[I'm a Red Motor fiend]

You said you had a Ford 2 barrel. Generally a Weber used on Holden 6's and far better than a 350 fuel funnel.

Edited by I'm a Red Motor fiend, 15 January 2022 - 04:38 PM.

[UCSLE]

have you got a vacuum gauge , whats it reading at idle ? what size is power valve ? 

[Bruiser]

Is the chamber in the main body behind the power valve wet?

[rodomo]

Exactly, if idle speed screw is holding the throttle discs/blades/butterflies open too far then fuel will be drawn from the transition slot effectively bypassing the idle circuit.

 

What is the idle speed?