Tuning a new quick fuel 850

[1970 RT Challenger 1970]

What advantage does a Quick Fuel Carb have over a Holley or any other Carb?

[Chryco Psycho]

I wonder if the orifice is sized as is & you can restrict it by adding bleeds to it , Call OF would be a good start , beats guessing .
 The Proform / QF carbs have built in adjustability in virtually every circuit , Holley is getting better with the HP & new Black Carbs series

[brads70]

Maybe shoot a quick email to QFC tech for a solid answer. I was told these were a Holley knock off and Holley parts could be used - supposedly manufacture is more closely scrutinized- does this look to be the case Brad? Also is the blue stuff on the metering block from the gasket - these gaskets are supposed to be reuseable with no stickum required(on a Holley anyhow)? These QF carbs are becoming very popular and I considered one but change can be difficult.

Email sent to quickfuel? Yep the blue stuff is just gasket residue. I reused the gasket.  Throttle response is wicked!  I've had numerous Holleys and a 850 Demon on my 440, and so far like the throttle responce with the quickfuel hands down!
 I have a fuel/air ratio gauge and it's running rich ( about 10.2, when cruising down the road, foot NOT in it) So I'm trying to get it running better.

Something has to be wrong as I dropped down 2 jet sizes and no difference on the fuel/air gauge?

[mojavered]

Brad, what made you want to go towards the 850 instead of the 950?  Air speed?  I went with a Proform 950 and my rear left (drivers side) air bleed was clogged.  Rear # 7 cylinder ended up washing, not sure how related they were.  There are a couple local speed shops round here and they really recommends the Quik Fuel carbs over the Proforms.
Did you weld the bungs with sensors in to get your AF ratio?

[brads70]

Brad, what made you want to go towards the 850 instead of the 950?  Air speed?  I went with a Proform 950 and my rear left (drivers side) air bleed was clogged.  Rear # 7 cylinder ended up washing, not sure how related they were.  There are a couple local speed shops round here and they really recommends the Quik Fuel carbs over the Proforms.
Did you weld the bungs with sensors in to get your AF ratio?

Don't know exactly why I chose an 850 over a 950?  I  guess I figured a 850 might be easier on fuel? 
Ya my next step when I get some time is to mess with the air bleeds after I hear back from quickfuel reguarding the possible missing emultion bleeds?.
Yep, I welded a bung into the passenger header. ( Just the one)

[Chryco Psycho]

Proform & QF are the same company , 850 is what I would have uysed also , 451X 2 is 900 , I would chose low side 512 X2 is 1024 so I have used both 950 & 1050 on those

[mojavered]

Forgot it was a 451.  Was thinking a 500"+.  Never heard that QuikFuel and ProForm were the same companies before.  Anyway, let us know what you hear.

[brads70]

I ordered a 2.5 power valve and 10 of the smallest size air bleeds. ( I can drill them bigger as I need to?) Should be here at the end of the week.

[Chryco Psycho]

I was talking with my local speed shop where I bought a lot of stuff , one day they had both QF & Proform carbs in stock & I said finally !!!!
 The guys at the shop said they are the same company so if you have access to one you get both , they sure are similar .

[brads70]

Ok a little update.... Thought I'd share my results for reference?
I have dropped down 2 jet sizes on the primary side, installed the 2.5 power valve and drilled the 4 idle circuit air bleeds from .073" up to .078"  This improved the A/F ratio on the gauge from 10.2 to 12.5 or so, and gave me some adjustability on the idle screws. I then tried drilling two more to .086 and installed them in the primary side. This made no difference in adjustability or on the A/F gauge. Just for kicks I tried removing one air bleed on the primary side while the engine was running and again it made no difference?  So that tells me I've maxed out on the air bleeds?
Vac at 900RPM's is 6.5, in park 4.5 in gear drops about 200RPM's to 700 or so

What to do next?
Jet down further on the primary side?
Jet down on the secondary side?
Drill 1/8" holes on the primary butterflies? ( no holes now?)

I never did hear back from Quick fuel reguarding those missing? brass inserts in the metering block? I'll have to phone them this week?
Also it's crappy and rainy here so I can't take her for a rip to see what happens when the 4bbls open up?

[brads70]

I phoned quick fuel today and they said the metering block for my carb doesn't come with the brass inserts . They said what Neil said .....drill ( .093) holes in the  front butterflies.....
and change the air restriction in the metering block from .028" to .032" and see if that helps with the idle screws being more responsive.

    

[HP_Cuda]

So the brass inserts are an upsell? Geez I thought Holley was bad but they started to machine things in like the check ball which rendered that moot with newer builds.

[brads70]

So the brass inserts are an upsell? Geez I thought Holley was bad but they started to machine things in like the check ball which rendered that moot with newer builds.

I think the idea is if you need to make them bigger than you can go back with the inserts if need be? 

[Chryco Psycho]

or with different carbs they change the metering but with the carb brad has the holes are drilled to size

[HP_Cuda]

I guess it's good to be able to go backwards but heck it wouldn't cost them hardly anything to include the inserts knowing that every motor build is different.

Again I'm asking too much of manufacturers these days.....