What jets to run?

[HitsonRacing]

:miss:
I have a 302, 9:1 comp., ported gt40x heads, x303 cam, 289 torker intake, big tube headers, 750 quick fuel racing carb, C4, 4.10 gears.

Quick Fuel says 84's squared but It fouls the plugs.

Any suggestions?

[White00gt]

Did you speak with QF? or buy the carb second hand? pull some jet, but I have no clue what to tell you other than start pulling jet till she cleans up. maybe 2 sizes at a time.

<--I know nothing about carb jetting, and the effects of jets sizes.

well. second thought, what heat range plugs and have you run the car and checked the plugs to see what they tell you? If this is just idle time it could be fouling cuz the plugs are too cold...my car will foul the plugs if I let it idle regardles of the A/F...it's because of the cold plugs I have to run to keep her from detonating.

[HitsonRacing]

I dropped the jets down and the car spits and sputters. I got the carb for a friend and it is brand new. I talked to the people at quick fuel and he told me to put 84's in it.

[HitsonRacing]

It does it at higher RPM only.

[White00gt]

if QF told you those numbers that should be a good starting point, if you gave them the correct info for your combo. other than that, you will need somebody who is carb friendly to help you with the low speed, idle, air bleed stuff, or your plugs are too cold. Have you run it on fresh plugs, and checked them? what did the fuel ring and timing marks lok like? did the plug have any heat in it\?

[HitsonRacing]

New plugs turn black after the first pass, I am running AR3935 (the hottest in the group)
everything else is set right. I put a 750 vac. secondary on the and the plugs clean up but the car fell off two tenths.

[White00gt]

The plugs were black?? that mofo must of been smoking like a freight train going down threw there..or.... to read plugs you must click it threw the lights then pull them and read them.. if you don['t click it a WOT your reading is null and void. If you drive it back to the pits null and void, idle null and void blah blah blah.

If they were black clicking it threw the lights then pull jets, if they were black after driving it back to the pits, then somebody who knows about carbs needs to help you

[HitsonRacing]

Thanks for your help! I think I will just put a 150 shot on it and ride!

[White00gt]

another 2nd thought.. what fuel? might not be burning the fuel.. you runing vp 110 or less? 9:1 = 93 octane pump gas

[HitsonRacing]

93 octane

[White00gt]

Thanks for your help! I think I will just put a 150 shot on it and ride!

That will get it, and if it's super fat lift ring lands at the sametime :) good luck.

[HitsonRacing]

That is what Big Daddy Dupree says to do!

[ShawnBoyMoody]

Hmmm. Im running 80/88s in my 650DP right now. Its a 306 with performer RPMS. You shouldnt be crazy rich with 84's squared. What about your power valve? Could it be blown or stuck?

[Pesce Nero]

84 squared, if it has a power valve then that is the problem


if you dont have the throttle blades set correctly then that could be another problem

trash in a air bleed could be another problem

[OUTLAW]

what trans do you have

[HitsonRacing]

There is no power valve, it has block offs front and rear.
I have a C4 transmission with a 4500 stall.
I have three differant linkages, 1 to 1, 40%, and 60%, right now I am running 1 to 1.
I was thinking about switching it to the 40% open linkage.

[OUTLAW]

You might want to try 82 but keep a eye on the plugs

[HitsonRacing]

I am open to give about any thing a shot right about now.

[Harry]

What kinda fuel pressure are you running?

[Darryl Buckner]

What kinda fuel pressure are you running?

Ding, Ding, Ding. Popping down track with a carb is usually fuel pressure related. Those BS Holley regulators that come free with a fuel pump, are just that BS! Easy way to tell is put a fuel line in the guage port on the regulator, and put the guage on the line under your windshield wiper so you can see it going down the track, and see what the pressure does. I run AR3911 in my 306 and a 950 carb from AED set at 81 square with power valves, 10.5 to 1 with B303 cam and Edelbrock 1.94 valve untouched heads.:bigthumb:

[White00gt]

I knew some Car-bi-nator guys would be along to help :)

[Darryl Buckner]

One day I am going to convert, actually already started, but those $200.00 each Moran injectors is a hard pill to swallow..:bigthumb:

[White00gt]

Yes but it is the last injector you will have to swallow :).. adjustable FTW just got me some 220's.. and man the spray pattern is B-E-A- utiful, compaired to the 160 bosh/ford CNg injectors I was running.. and the flow rate isn't all fubared around 1-3ms, ahh they are nice.

[bwelch]

How much for the 160's if they are still good?

[HitsonRacing]

I am running 7 lbs of fuel pressure. I have a oil filled fuel pressure gauge mounted at the outlet of the regulator.
I am going to change the carb to a 750 vac secondary and see how it runs.
It use to run fine with the 750 vac secondary on it before.

[Darryl Buckner]

Electric fuel pump? If so, does it have a return to the tank?

[HitsonRacing]

stock in tank electric fuel pump with return line

[Harry]

I am running 7 lbs of fuel pressure. I have a oil filled fuel pressure gauge mounted at the outlet of the regulator.
I am going to change the carb to a 750 vac secondary and see how it runs.
It use to run fine with the 750 vac secondary on it before.

7lbs could be a little high. Try 6 and run it. If that doesn't work try 5 lbs. I wouldn't go any lower than 5lbs though. Anywhere in between thouse #'s will work also to fine tune it.

[WWhittle]

Are u driving it back to the pits and checking the plugs? If so, of course they are going to be black. If u want to read your plugs you need to shut it off as soon as you go through the traps and tow it back.

[BigdaddyDupree]

Kill it at the eighth let it coast pull a plug swap a new one with it. Drive it to the trailer. Read the plug. Adjust.

[Illusions]

Are u driving it back to the pits and checking the plugs? If so, of course they are going to be black. If u want to read your plugs you need to shut it off as soon as you go through the traps and tow it back.

x2, every serious nitrous user I know does it this way while tuning it. :cheers

[WWhittle]

Kill it at the eighth let it coast pull a plug swap a new one with it. Drive it to the trailer. Read the plug. Adjust.

If you are going to do it this way, I would pull atleast 2 plugs. One from the front and one from the back.

[WWhittle]

x2, every serious nitrous user I know does it this way while tuning it. :cheers

Yeah, the only way to tune off a set of plugs is to have a fresh set of plugs and shut it off as soon as you go through the traps. Otherwise, you are trying to tune for WOT off a set of plugs that are showing you your idle and part throttle.

[Illusions]

Yeah, the only way to tune off a set of plugs is to have a fresh set of plugs and shut it off as soon as you go through the traps. Otherwise, you are trying to tune for WOT off a set of plugs that are showing you your idle and part throttle.

That's why i have a 4wheeler at the track. when we make changes up or down in jet size she gets towed back and plugs read. :cheers

[RobertHolton1]

stock in tank electric fuel pump with return line

so did you fix your problem