kunkles thread on diesling had me curious so i went out to play with my demon 750 double pump today. im still in the fine tuning stages of another car its on . what i want to know is 2 things.

1- firstly the idle mixtures , as its a 4 corner unlike the holley 2 corner does that mean roughly all i should be doing is 1/2 turn out from lightly seated on each screw.

2-secondly i always adjusted my idle using the carburetter adjustment on the driver side of the car . i always knew about the other spring loaded adjustment on the other side which looks the same but i have never fiddled with it.( arrows point to them in the pic ) please tell me exactly what each one does and what i should be doing to set them correctly. i can see my plates opening and closing when adjusting idle on the driver side but when i adjust the other side it does make a rev change but i cant see anything mechenical going on.

3- another point is the easy idle down the stud hole. i do have a slot down there which does turn but doesnt seem to do much so dont worry too much about that.

 

No expert by any means, but I do have an 850 Demon on Ol' Red.

Pull the carb and set the throttle plates so the transfer slot looks square on BOTH primary and secondary- I didn't do this at first- I slapped it on and tried to adjust it like the old 2 idle screw Holley- it Don't work.
run all the idle screws in and back them out 1-1/2 turns. Lightly seat the Idle-Eze- that's the one down the air cleaner stud hole. If you've got a long duration cam you'll get into this one- if not, closed is where it is for now.
Put the carb back on, fill it with gas and start and leak check- you might have to play with the throttle to keep it running. Hook a vacuum gauge up and see where you're at- Adjust all 4 mixture screws the same amount- if you turn the left front 1/4 turn, do all of them that same 1/4 turn. If you just flat can't get any idle, open the primary idle speed screw up a little bit- keep track of how much 'cause you want to get it back where it was- Keep running around looking at the vacuum gauge and tweaking the idle mix screws for the highest vacuum- as the idle gets better, start taking your pimary idle back to it's original point. After you get the mixture screws adjusted evenly for the best vacuum, and the idle screw back to where you started, if the idle is low then open up the idle-eze a bit, then go thru the idle mix screws again- 3 or 4 trips and it'll all of a sudden get really good- weird, but that's how it worked for me. And now- no more burning eyes, no real bad stink, and it's running great. Even cold with NO CHOKE- pump the pedal 2 times, count to 10 and crank it. Starts like, right now. Still have to play a little footsie, but once is sees a little heat it settles down and idles fine.
Sorry, kind of long, but that's how it worked for me. I did it again after I swapped to a 4.5 power valve- the factory one was opening too early and made it stink at idle.

 

I did much the same, except I left the idle eze closed, runs great!

 

oh man O man ... did it have to be such a long answer . i was hoping for a turn of this and a turn of that and a quick explanation of the adjustments. taking off carb is at least another 6 pack . the car does hammer and does idle perfectly with a little footsie at the beginning but i will follow your promps next chance i get.

 

Doesn't sound like you're far off, setting this up as indicated is definately worth the time. You will see a world of difference in drivablity from a pain to a pleasure.

 

I will bet you will end up closer to 1 turn out max, more like 3/4, depends on how much vacumn you are pulling. I used to tune the idle circuit by using the highest vacumn reading method. Once you get an air fuel meter you will see that once you get the highest vacumn reading, lean out each screw another 1/8th to 1/16th of a turn (turn in) and you will be right on the ideal air fuel ratio. When the AF ratio is correct and your car has no choke, it will run like **** untill warm!! If your car runs on its own without a choke, you are way to rich

 

For my demon, I usually just slap it with some Holy Water and scream THE POWER OF CHRIST COMPELS YOU!!!!

 

When I got my demon I read everything I could about how to set up Holley carbs. The Demon web sight has some good tips also.

You need a vacuum gauge and a dial back type timing light.

With a little work you can become the carb expert!

 

That is the laugh of the day for me

The screw on the opposite side of your throttle (passenger side) that looks like another curb idle screw is for adjusting the secondary throttle plate opening.. This is very convenient for cars with large duration cams with off idle stumbles. I would leave this screw alone until you verify you have good off idle response. The main curb idle screw on the throttle side of the carb (drivers side) is for adjusting your main idle speed. Use this screw to get your main idle where you want it and then if you get an off idle stumble after taking it for a test drive, you will need to tune the secondary throttle plate opening.. If you get an off idle stumble, let me know and I can walk you through the resolution..

 

Fishndude... what should I do if I have a slight off idle stumble? I havn't touched the secondaries idle screw from the initial setting...

 

I dont know about the Speed Demons but I have a new Might Demon and they are specificially calibrated from the factory for large duration cams (over .240 @ .050). They come with the secondary plates already open slightly to accomodate for the off idle stumble that will usually happen with a large cam and standard carb. If you have a off idle stumble, see if the secondaries plates are open at idle.. If not, you want to start out by having them open to .015-.020 and the best way to get an accurate measurement is by removing the carb, turning it over and using a narrow feeler gauge (I cut mine down) becasue a fat feeler gauge will not fit due to the radious.. Large dur cams dont have good vacuum at idle so they dont draw well off the idle circuit so it usually requires turning up the main idle screw (curb idle screw) to get an adequate idle but by doing so you expose the primary transfer slots. This causes the motor to start drawing fuel off the main circuit, which causes a very rich idle mixture and an off idle stumble. The cure is to open up the sedconday throttle plates, which increases the idle speed and allows you to go back and turn down the main idle screw (primary throttle plates), which then un-exposes the transfer slots again. This usually solves the rich idle and off idle stumble that is so common with the large cams.

 

thanks to everyone. i have come a long way with all your information and fishndude yours was particularly valuable.