holley wire mod

[baxsom]

maybe you guys can help me get a holley tuned on my old mustang. something that i read here that i have never seen on any of the classic mustang sites said that a lot of them run rich at idle regardless of how far in the idle screws are. that is what this one is doing.

so i read about the wire mod. putting a .015 wire in the restrictors inside the metering block. seems to help a lot in many cases. i went to hobby lobby to find some rod and the closest that they had was .016 brass rod. is that .001 of an inch going to make a difference or should i hold out for another source.

thanks

 

[Rodney Gold]

IMHO The better bet to get the car to respond to the idle screws is to
1) Drill a small hole in the primary butterflys
2) And do that ONLY AFTER you cannot get the car to idle correctly after having adjusted the little screw that sets how much of the transfer slot the throttle butterflys expose.(need to take the carb off for that)
I would NOT put wires in the restrictors

 

[baxsom]

i have read about that too but in every case that it comes up here it is always mentioned as a last resort since it is permanent.

the wire in the bleed restrictor trick is talked about a lot here. (that is what i get for searching)

 

[baxsom]

IMHO The better bet to get the car to respond to the idle screws is to

2) And do that ONLY AFTER you cannot get the car to idle correctly after having adjusted the little screw that sets how much of the transfer slot the throttle butterflys expose.(need to take the carb off for that)
I would NOT put wires in the restrictors

you mean the fast idle screw?
there are two screws on a holley that set the butterflies
the fast idle and the curb idle.
neither of them require removal of the carb.

i have the 4160 taken apart to every last screw, part, and gasket on my workbench now.

 

[Rodney Gold]

Its the screw that allows you to allow more or less of a throttle butterfly slot when the throttle is closed , tuning it allows some carbs to idle normally and respond to mixture screws. its under the carb , it cant be set while the carb is attached.

 

[baxsom]

well like i said that is either the fast idle or the curb idle.
i have the baseplate for the carb in question fully taken apart with the butterflies off and the shaft out and those are the only two screws that stop the butterflies from going farther forward.

what i dont understand though is that both can be adjusted with the carb on the car. so without a picture showing this third screw i am lost.

 

[Rodney Gold]

Well , if you can be a contortionist and get under the baseplate of the carb , you can maybe adjust it , I dunno the exact name , but I think its called the Secondary idle speed adjustment screw and its under the baseplate in a recess right near the secondary vacuum pot/secondary throttle shaft side of things. It allows the scondaries to either be closed or slightly cracked when at zero throttle. Good luck with trying to adjust it when the carb is on the car.........

 

[Hib Halverson]

Inserting wires into the idle circuits of the metering block to lean the AFR at idle and part throttle is a common, accepted tuning technique with Holleys. That said, typically, you only need to do that when you are trying to adapt a racing Holley to street use. The initial post doesn't say what kind of Holley is being installed on this Mustang but if it's a Holley intended to replace the OE carb, I'd make sure there isn't another problem with the carb (an internal fuel leak, perhaps) that's causing the problem at idle.

Now, several of the posts above talk about drilling the throttle place or adjusting the secondary idle speed screw but, if we assume that the diagnosis of overly rich mixture at idle is correct---neither of those ideas will work because they address problems with either idle speed or the location of the throttle plates in the primary bores when the primaries are at curb idle.

As for what kind of "wire" to use, the best stuff are the strands of common automotive electrical wire, either copper or aluminum. I have tons of scrap wire in my electrical scrap box. When I'm fooling with the restrictors in my Holley idle feed restrictions, I cut several 1/2-in lengths of different gauge wires, strip the insulation then pick out several strands and measure their diameters with my micrometer. Once I find two I want, I bend them into "V's" and insert them into the IFRs, put the carb back together and go on a test run using my wide-band O2.

I've tuned Holleys this way for nearly 20 years and the 850 on my 71 Coupe has had wires in the IFRs since the early 90s.

 

[Rodney Gold]

This might help a little
http://www.fordmuscle.com/archives/1999/12/holley/index2.shtml