Tuning a new quick fuel 850

[brads70]

HP_Cuda I understand what your saying.

Ok all back to tuning....
I drilled two holes (.093") , one in each primary butterfly. The idle mixture screws have me puzzled? When I bottom them out and then wind them out 1 1/2 turn as a baseline it runs horribly rich.... like black smoke and burning my eyes out. When I wind them back in all the way it runs much better, I then slowly wind them back out to 1/2 a turn from bottomed out and thats where it runs the best I get a pretty consistant 13 on the fuel air gauge.
( Improving! )  What I don't understand is why it gets so rich when I go any further? My understanding is it's suposed to get leaner the more you wind the idle screws out? 
Just thinking .... maybe I need to open up the passage in the metering block that draws the air from the idle bleeds? It does have a screw in air bleed in that passage to control the air?
To my way of thinking if the air bleed restriction in the metering block is to small them one would think that the idle mixture screws would have no effect the more I wound them out?, not get bad rich?

 

I have ordered a #61-80 drill set , it was supposed to be here today but it didn't show up yet. I'll need it to drill open the metering block idle air bleed restriction.

[bandt]

Hey Brad,

My understanding is the opposite of yours with the idle screws.
With the screw bottemed out that would be blocking off fuel completely. As you turn it out it allows more fuel to pass through. Typically if the carb is sized and matched well you want to see 1/2 to 3/4's of a turn, so you are bang on as far as where your screws are.

But I have been proven wrong.........lots.

Brian

[Chryco Psycho]

I agree , bottomed out is lean & stop fuel flow , the more you turn them out the richer it gets , also opening up the bleed should lean it as well .

[brads70]

   Thanks guys! LOL wouldn't be the first time I thought back ass wards
 So to lean it out further at idle I have 3 options? ( correct me if I'm wrong?)
1  smaller jets
2 drill 2 more .093" holes in the secondary throttle plates ( butterflies) this seemed to change the A/F gauge by .5 on the front ones?
3 install a smaller idle feed restriction in the metering block ( see diagram in link)
http://www.quickfueltechnology.com/technical-info/3-circuit-metering-block-information
A/F gauge currently is at about 13.0 at idle, in the instructions with the gauge it says 14.7 is optimum?

Which one?

[Chryco Psycho]

1] The jets feed the boosters which are dry at idle so changing jets will have no effect on idle .
2] Drill 2 more holes in the throttle plates , this will allow more air under the throttle plates without exposing more of the transfer slot .
3] this may work also by limiting the amout of fuel available to the idle circuit but if you are under capacity now it may make no difference .
4] installing larger air bleeds for the idle circuit usually helps as well as the vacuum to draw in fuel through the idle circuit will have less effect .

[bandt]

The other thing you can try is putting more initial timing in it. Not sure what you have in it for timing now but typically as you add timing RPM will increase (to a point). The benefit of that is you can turn down your curb idle which may be enough to get out of the transfer slot if that is the issue.
I would keep messing with your idle screws. You will notice with the wide band they are very touchy. As little as a 16th of a turn will effect your AFR.

Brian

[HP_Cuda]

Hmm horribly rich at 1.5 turns out..

What kind of vacuum do you get at 1/4 turn out? Like Cryco said drill two more holes should allow more airflow and cut the richness.

Btw, what kind of cam and heads you have on this again?

B

[brads70]

Hmm horribly rich at 1.5 turns out..

What kind of vacuum do you get at 1/4 turn out? Like Cryco said drill two more holes should allow more airflow and cut the richness.

Btw, what kind of cam and heads you have on this again?

B

I haven't had time to drill the other 2 holes but I will soon. Here is my cam card ( hyd roller)
http://www.lunatipower.com/CamSpec.aspx?p=60312

Heads are fully ported Mopar stage 6 aluminum heads in gear I get 4 inches of vac ( 2.5 power valve installed, dropped down 2 jet sizes from "stock" )

[HP_Cuda]

Hmm you cam is very close to what I have. What kind of flow numbers you have on your heads?

Are you running 2" headers? TTI? etc?

[brads70]

Don't know the flow #'s?  Headmann headers 1 7/8" I think?

[brads70]

  success!  It bounces around between 14 and 14.5 on the A/F gauge at idle now! ( Idles at 750-800 RPM's) Doesn't stink up my garage/house while in then garage now! 
I drilled the secondary butterflies the same ( .093") as the primaries and used the secondary adjustment screw to slightly open/fine tune . Worked great! I've never had a carb with that secondary adjustment screw adjustable from the top. Nice feature to have! LOVE this carb! 
Your right Bandt about the 1/16th adjustments on the idle screws being so sensitive on the A/F gauge!
Also got he vac up another 1/2 to 1 for a total of 5" at best. It bounces around with the idle.
Had a fun evening messing around with this tonight! 

[Chryco Psycho]

 
 I have done this a lot but without the A/F meter

[HP_Cuda]

Way to go Brad, your rings will thank you for not running rich either!

 

[brads70]

Today I decided to rip the  carb apart to apply red loctite to the butterfly screws as they had used it before I took them off to drill the holes in them I took a few more pictures thinking other might like to see whats inside one?
Neil is correct in that Proform and Quickfuel are the same company . In this picture it's cast into the main body, on the other side it says quickfuel


Picture of the .093" holes I drilled...



I never "trust" anyone's work so I ripped it right down to inspect everything. When I did I found this brass thing  was holding up the main body some, so I filed it down flat.
 


Here are a few pictures of the secondary metering block...




This is the screw in air bleed I'll drill out a few thou at a time when I get the drill set I ordered. This allows more air to the idle screw mixture. Quickfuel suggested I drill them bigger on both metering blocks for my application. I believe the idea is to make the idle screws more effective. Only out 1/2 a turn or so now?
 

[HP_Cuda]

Cool pics Brad, glad everything is working out. I'm still a bit shocked at the low power valve (2.5) but I guess if you are 1-2 points below where the car idles then you are on top of it. Now I wonder what kind of vacuum I'll see and if I will have to add a vacuum canister for my power brakes.

Oh the price we pay for fun...

Btw, you are at about 1000ft so you would have dropped 1/2 a jet size right there but still....