Carbed lq4 help

[pontiacgp]

what is your fuel pressure? and how far out do you have your idle mixture screw?

 

[Ryanmjw]

At idle the car is at 10.9 and when your behind it it burns your eyes bad

 

[Ryanmjw]

I had the fuel pressure at 6psi that's what the carb calls for but I went all the way down to 2 psi and they are 1.5 turns out but I went from 1/4 turn out all the way to 2 turns out on the air fuel screw

 

[pontiacgp]

for idle you should be able to get it to 14.7 with the idle mixture screws. If you turn the screws all the way in will the engine die?

 

[Ryanmjw]

That's the thing it doesn't change if I turn the screws only if there all the way in it kills it anything else it dosnt matter

 

[pontiacgp]

That's the thing it doesn't change if I turn the screws only if there all the way in it kills it anything else it dosnt matter

?

 

[vanrah]

Greetings Ryanmjw & all; I've been playing around with Holley carbs since 1969 & I've learned enough to get myself into trouble. I've read your thread & I'll take a couple of shots. First double check your timing, I'm under the impression an Ls engine doesn't like very much? Second I feel that you may have the blades open too far for the idle circuit to work properly? As your idle screws aren't doing much! That's why I want you to check the timing. Next you may have a power valve failure, either check it or put in a new one. And make sure that it is at least 2 & up to 4 numbers below your idle vacuum. I also learned the hard way that Pro Form- Quick Fuel metering blocks want a very thick gasket (red from QF) on the power valve, as the threads don't seem to be as deep as on a Holley block. And last if you think how a power valve works, you soon understand why many do not run a secondary (rear) PV. As the fuel is pulled away from it under hard acceleration & it tends to go lean just when you want it to feed the main circuit, making tuning a problem. But when you plug or have no secondary PV you will need to jet the secondaries 6 to 10 #'s richer than the primary side. Keep in mind that the jets flow when you open the blades (possibly why your idle screws do little) & under full on the the PV opens to add extra fuel. You don't want that extra fuel under part throttle cruise (PV closed). So when you no longer have a secondary PV you have to add more jet to compensate for no PV flow. Good Luck, Ol'e Bob.
Ps: I usually call Quick Fuel about every other year with a new question, their tech line guys are very helpfull.

 

[Ryanmjw]

Thanks for all the help but I took the carb to the local speed shop and they said it was junk so I returned it and got a holly hp and the car runs great the guy at summit said they have had a lot of the quick fuel carbs being returned

 

[pontiacgp]

Thanks for letting us know....🙂

 

[64nailhead]

Thanks for all the help but I took the carb to the local speed shop and they said it was junk so I returned it and got a holly hp and the car runs great the guy at summit said they have had a lot of the quick fuel carbs being returned

I'm really glad you got it running properly, but I'm not buying what you were told. vanrah was onto your issue, but you jumped ship too soon. Almost for sure your idle transisition slot had too much exposure causing fuel to be sucked in from the secondaries at idle, hence the reason why your idle screws had little to no affect on idle AFR. It sounds like you bought a scond carb, bolted it on and it's working - FYI - that is almost unheard of for any Holley of Holley look alike (QuickFuel being one.) The expectation is that you are going to tune it to your motor. Personally I despise carbs and will hopefully never mess with another (until someone shows up with one and asks me too help them with it - lol), but they are time consuming to tune and require an understanding of how they function. I'm sure that a call or two to QuickFuel would've resolved your issue in a hurry. QuickFuel makes a good carb and is praised by many.

My two cents - take it for what it's worth ($.02 - not much 🙂)