Bracket Talk
4500 sticking open
May 22, 2021, 08:23 PM
chasracer4500 sticking open
My QF alky 4500 is sticking when you open it completely. I can put a stronger return spring on it but I don't think it should be sticking like it is.
Suggestions?
May 22, 2021, 09:39 PM
Canted ValveMy first response would be to look at the throttle shaft.
Illegitimi non carborundum
May 22, 2021, 10:09 PM
Curly1I agree the throttle shaft may be worn out. Many people have their return springs set up wrong. They must pull inline with the throttle cable or rod. Many put the return spring on same side as the cable on bottom of the shaft. That means when you pull the throttle open both the spring and the cable are pulling same direction and putting too much stress on the shaft if that makes sense. That wears it out and puts it in a bind.
But you must fix it. Try taking the spring and cable off and verify that the shaft is not sticking and worn. If that is all smooth then check out the cable itself while disconnected and verify it is smooth.
https://postimg.cc/gallery/np3zpruo/"Dunning-Kruger Effect"
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May 23, 2021, 01:19 AM
imakehpAssuming the carb still has internal linkage, take the carb off and turn it upside down and carbclean the linkage well then oil it well and see if that corrects the issue.
I've even used motorcycle chain oil because it's made to cling. Also use a 4-h0le gasket so it seals the linkage cavity from air/fuel flow removing the oil.
if that doesn't fix it check the throttle blades are still centered up in the bores.
You did remove the throttle cable/rod when checking the bend right?
.
Dave
F J B
May 23, 2021, 06:43 AM
SP 124XI have to lube my throttle shafts on the regular on alcohol. I also seen this problem on cars with no other noticable problems and it was white death around the squirter check ball holding pressure on the arm/cam. I'd start by taking both bowels off and confirming it still sticks then look at the throttle shafts.
Denis LeBlanc
May 23, 2021, 11:50 AM
chasracerCarb shafts were okay but gave them a few drops of machine oil. Throttle cable seemed to be good, gave it a few drops on each end. Put a slightly heavier return spring on and carb doesn't stick open now.
Thanks for the help and suggestions.
May 24, 2021, 08:55 AM
FootbrakeJimI have an older 4500 on the shelf, bought it fairly cheap, seller said it would stick on him. The throttle shaft is worn, and very slightly twisted.
Does anyone know any company that sells replacement throttle shafts for Dominators?
I've checked with Holley and BLP, no luck...
Dan "Jim" Moore
Much too young to feel this damn old!!
May 24, 2021, 11:53 AM
nomadTweak the secondary pump arm where it rides on the pump cam. Some times the arm will lay flat on the back side of the pump cam. Sometimes a slight curve in the arm contact area will help.
nomad
Bruce Guertin
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May 24, 2021, 01:08 PM
Brktracerquote:
Originally posted by FootbrakeJim:
I have an older 4500 on the shelf, bought it fairly cheap, seller said it would stick on him. The throttle shaft is worn, and very slightly twisted.
Does anyone know any company that sells replacement throttle shafts for Dominators?
I've checked with Holley and BLP, no luck...
Hmmm. BLP has them as part of their kit for the external linkage. Very nice setup.
https://blp.com/cart/index.php...info&products_id=391Instructions (who needs them, lol)
http://blp.com/help-center2/30...linkage-installation
Matt Ward
May 24, 2021, 02:09 PM
nomadYou need this item from BLP.
nomad
Bruce Guertin
Easily distracted by bright shiny objects.
Wife says I'm a new adventure every day.
Call Automotive Performance Engines for all your complete engine building, dyno service needs 863-967-8781
May 25, 2021, 07:21 AM
chasracerSure looks like putting a minor curve in the arm is a lot easier and a bunch cheaper!
June 09, 2021, 10:25 PM
jmarkaudioBLP's shaft kit fits the Quick Fuel body just fine. Their newest shaft kit has the secondary return set screw setup as part of the shaft. The other issue is usually a pump cam hopping up on the flat, not giving it help putting pressure to return the shaft. Some cam massaging or different cams will fix that.
Mark Whitener
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June 10, 2021, 06:18 AM
Rob7181I thought I had the same problem. Took the cable off and problem went away. Cable had a hitch in it that was enough to make the carb stick. Tap peddle and it would return. Replaced the cable and problem was solved.
Rob Robertson