Help with info a 425 mixer

crawler nut · Feb 23, 2013

Just bought a new 425 mixer to replace my old one. Got it all put on a fired it up adjusted the idle.
Backed it down the drive way, an when I stomp it an runs up to about 3500 rpm an then after that its like it is running out of fuel.
The engine is a GM 355, flat tops, 58cc heads.
It idles great just seams to run out of fuel. My old hat didnt do this.
Is there an adjustment for this? If so which adjustment is it? Thanks.

altfuel1991 · Feb 24, 2013

re you running a vacuum lockoff valve, if so where is the hose connected to vacuum? It should be connected to a ported vacuum source. This will provide a constant source of vacuum to keep the lockoff valve open. If it is connected to manifold vacuum at WOT there is zero vacuum and the lockoff will close and shut the fuel off.

You should not have to adjust the power mixture if you have a real IMPCO 425 mixer. They are all flow tested and adjusted when manufactured. If the above is not a problem I would check for vacuum leaks and also check the vaporizer. You can test the output pressure at the test port. It should be 1-1/2 to 2 lbs.

If you still can't find anything, give me a call and we can figure it out. Propane systems and repairs are what we do. And no you don't have to buy anything from me to get technical help.

Buddy Gamel
Precision Sales & Service, Inc.
451 64th Place South
Birmingham, Ala. 35212

877-403-7827
205-591-2267, fax

[email protected]
[email protected]
www.alternatefuel.com
www.workhorseservice.com

crawler nut · Feb 24, 2013

altfuel1991 said:
re you running a vacuum lockoff valve, if so where is the hose connected to vacuum? It should be connected to a ported vacuum source. This will provide a constant source of vacuum to keep the lockoff valve open. If it is connected to manifold vacuum at WOT there is zero vacuum and the lockoff will close and shut the fuel off.

You should not have to adjust the power mixture if you have a real IMPCO 425 mixer. They are all flow tested and adjusted when manufactured. If the above is not a problem I would check for vacuum leaks and also check the vaporizer. You can test the output pressure at the test port. It should be 1-1/2 to 2 lbs.

If you still can't find anything, give me a call and we can figure it out. Propane systems and repairs are what we do. And no you don't have to buy anything from me to get technical help.

Buddy Gamel
Precision Sales & Service, Inc.
451 64th Place South
Birmingham, Ala. 35212

877-403-7827
205-591-2267, fax

[email protected]
[email protected]
www.alternatefuel.com
www.workhorseservice.com

I am running an Electric Lock off, Likie I said above, I just replaced the other hat, because I was messing with the adjustments an got it screwed up. An just bought a new one. I put it on an it does this about 3500rpm. I there someone I can send my other hat to to have adjusted where it needs to be? I am getting ready to build a strong 406 an will be running 2 hats. I really do appreaciate your help.

alscott · Feb 24, 2013

take the wot screw (the big one in the front) an turn it out until you get what your lookin for. sounds to me like its turned in to far an your starvin it for fuel

crawler nut · Feb 25, 2013

alscott said:
take the wot screw (the big one in the front) an turn it out until you get what your lookin for. sounds to me like its turned in to far an your starvin it for fuel

What does the WOT stand for? I will try that, I really do appreaciate all of you guys help. Thanks again.

Lil ugly · Feb 25, 2013

WOT= Wide Open Throttle.

altfuel1991 · Feb 25, 2013

I would have to agree if the power mixture has been changed it may be in too far. Bring it out about 1/2 to one round at a time and try it again. You can also take the air valve out of your old mixer and look inside to see where the restrictor plate is positioned and then check your new one and compare. Does your new one still have the restrictor washer in the fuel inlet? If that has been removed it will deal you headaches as well.

crawler nut · Feb 25, 2013

altfuel1991 said:
I would have to agree if the power mixture has been changed it may be in too far. Bring it out about 1/2 to one round at a time and try it again. You can also take the air valve out of your old mixer and look inside to see where the restrictor plate is positioned and then check your new one and compare. Does your new one still have the restrictor washer in the fuel inlet? If that has been removed it will deal you headaches as well.

Thanks to all you guys for the much appreaciated help. I will check all the things mentioned an get back if they all fail, an will take it from there. Thanks again Dustin

crawler nut · Feb 27, 2013

The WOT screw worked like a champ. Ended up going out 1-1/4 turns an I think she is real close. Thanks again guys I really do appreaciate the info. :dblthumb: