leaning out center carb on my a12 superbee.

was wondering what is a good jet setting for the center carb for idling and part throttle. i think i'm too rich.
Also whats a good Autolite racing plug for a 11.0 compression 440-6?
I'm running a AR73 plug and i think its too cold.

if the engines stock you don't need anything more than a 64 main jet in the center carb. idle mixture screw settings may depend. i've found the mixture screws on the end carbs turned out 3/4-7/8 turn works good with the center carb screws 1/2-1 turn out. i prefer the j11y for iron heads. an autolite 85 is a reasonable substitute and wouldn't go any colder than a 74. i like the j11y because it has a longer tip, near perfect heat range, and was designed for the mopar head.

if the engines stock you don't need anything more than a 64 main jet in the center carb. idle mixture screw settings may depend. i've found the mixture screws on the end carbs turned out 3/4-7/8 turn works good with the center carb screws 1/2-1 turn out. i prefer the j11y for iron heads. an autolite 85 is a reasonable substitute and wouldn't go any colder than a 74. i like the j11y because it has a longer tip, near perfect heat range, and was designed for the mopar head.

X2

if the engines stock you don't need anything more than a 64 main jet in the center carb. idle mixture screw settings may depend. i've found the mixture screws on the end carbs turned out 3/4-7/8 turn works good with the center carb screws 1/2-1 turn out. i prefer the j11y for iron heads. an autolite 85 is a reasonable substitute and wouldn't go any colder than a 74. i like the j11y because it has a longer tip, near perfect heat range, and was designed for the mopar head.


i have has 2 sets of j11y's get fouled out on me. its a pure stock motor that goes 11.97-12.00 with 11.0:1 compression.
Best Machine suggests AR73 autolites for racing.I think they are a touch too cold.

ar73 is colder than a j11y. if the plugs are fouling something else is wrong. any oil tracking on the plugs?

ar73 is colder than a j11y. if the plugs are fouling something else is wrong. any oil tracking on the plugs?


this was my original a12 car and i sold it to a guy in michigan. rebuilt everything and blocked the heat crossovers under the manifold and disconnected the choke.
i bought the car back years later, runs better but fouls plugs now. plugs look rich.no oil that i see

Part of the problem might be the cold plug. Is your ignition up to snuff? The 64 jets should be all you need with an otherwise unmodified carb. Are you running a factory metering block?

if theres no oil tracking and its just dirty plugs a simple test would be to try a set of 85's. they do seem to burn cleaner for me. i've found that bosch 4036's burn fairly clean. i don't run a cold intake, prefer some kind of regulated heat for drivers.

if theres no oil tracking and its just dirty plugs a simple test would be to try a set of 85's. they do seem to burn cleaner for me. i've found that bosch 4036's burn fairly clean. i don't run a cold intake, prefer some kind of regulated heat for drivers.

im going to pull the intake and put in the oe valley tray, this weekend going to check what jets are in it and change accordingly. im betting the jets are way fat.

what i've done in the past is get the felpro gasket that has blocked heat and poke a 5/8" or 3/4" hole in the block-off panels (both sides) to allow some heat but still have some control. full open is too much and the holes add some regulation. on the engine in my 65 coronet i made a butterfly valve and put it in the manifold crossover. turn the heat on when its cold, shut it off when its hot. i also made a separate valley pan for the cast iron heads (a little complicated) to eliminate any oil being sucked thru the intake gasket.

what i've done in the past is get the felpro gasket that has blocked heat and poke a 5/8" or 3/4" hole in the block-off panels (both sides) to allow some heat but still have some control. full open is too much and the holes add some regulation. on the engine in my 65 coronet i made a butterfly valve and put it in the manifold crossover. turn the heat on when its cold, shut it off when its hot. i also made a separate valley pan for the cast iron heads (a little complicated) to eliminate any oil being sucked thru the intake gasket.


i like this idea alot, so then i'll be able to use my choke again and have it work like it is supposed to. it was not my idea to block off these crossovers. i may do this tomorrow if i get my honey do list finished.
also going to lean out the jetting on the center carb to factory spec or atleast lean it a few .

if you have an original '69 choke, they're adjustable.

if you have an original '69 choke, they're adjustable.

yes its an original choke, everything on it is oe equipment just the motor is rturned up a notch or two.

on the engine in my 65 coronet i made a butterfly valve and put it in the manifold crossover. turn the heat on when its cold, shut it off when its hot.
I don't mean to highjack the thread but could you please provide an example of the heat cross over butterfly valve you designed? I live in Fla. and the heatsoak the manafold goes through in mid summer would be greatly reduced (i think) if i had the option to shut the crossover.

i did the same thing to a ch28 intake thats not on an engine. i'll see if i can dig the manifold out and get some pic's of it. a little work but worth it if your using iron heads.

see if this works

VERY COOL!
It's one of those things that when you see it, it makes you wonder why you (me) didn't think of it in the first place.
Thanks again!

i used to have some pictures of the valley pan i made for iron heads to get rid of the factory valley pan/gasket. that ended being a fairly neat item and is on my 65 coronet now. no more sucking oil thru the intake!