baseline jetting for sixpack

[aarcuda]

I have the promax metering clock, jet plates and base plates for my small block 416 sixpack and was curious what you would use for a baseline jetting and IFR and emulsion sizes.

my motor is a 340 mopar stroked to 416. 9.7:1 compression. hughes solid cam at 565/575 lift, 245/250 duration at .050. hooker supercomps, 727 trans with 3000 stall and 4.30 gears.

i started with 66 jets in the center carb and 84's on the outboards, 2.5 power valve. i had 2 holes drilled thru the throttle plates. 20 degrees initial timing and 34 degrees total all in by 2500 rpm.

it will idle at 1050 in nuetral and down to 750 in gear with 13" vacuum at idle in nuetral and 6-7' in gear.

The mixture showed to be a bit rich at wot and cruise at around 12.0: and into the 11's so I changed it up (a bunch)

I went to 64 jets in the center, 80's front and back, 4.5" power valve and closed up the throttle plat holes. the cruise mixture went to 13.5:1 or so which seems good. I dont have a good wot mixture yet.

my idle mixture seems real lean though but i have an exhaust leak so i dont really trust the 16-17:1 i am reading when i drop it in gear (the mixture is also very irratic at idle).

when do you typically mess with the IFR or the emulsion jets? Im looking for typical jetting setups for similar combos (although I know thats asking for a lot)

[ProMax]

A motor will normally run a little leaner once you put it into gear. When tuning on the dyno, I will have the A/F just a little rich with no load. Then oncle the load is applied it seems to clean out. Its not a big jump or anything like that. I would keep tuning with mixture screws for now on the idle curcuit, unless you just cant get to where you want to be. Then start tuning the mid and WOT settings with jets. If you have 13" of vac at idle you may want to go up to a 6.5 pv. Hope this helps!


Thanks

Ben J. Gorman
PROMAX Performance

[aarcuda]

thanks, the 13" of vacuum in in neutral and it drops down once i put it in gear. i did take it to the track and i lost some time going to the 64's and 80 jets from the original 66's, and 84's. I had been running 10.2 in the 1000' and it dropped to 10.5' with the smaller jets

So I changed the PV to a 4.5", center jet is still at 64, outboards went back to change the power valve. soldered up the holes in my throttle plate, changed the secondary springs from a plain spring to a brown spring.

I havent been back to the track yet (remember this is mainly a street car and the track 100 miles away) but the LM1 plot shows a much quicker acceleration than before.

I am getting a lean spike right around 2800 rpm in first which is where my converter stalls at. The accel ramp changes showing a slower acceleration and when the spike goes away, it accels pretty well.

I am also seeing a lean spike in 2nd gear from 5000 to 6000. I plan on fattening up the outboard jets a little more to see if I can cure it.

Here is the LM1 plot with the brown spring in

board.moparts.org/ubbthreads/upload2/5241617-5236813-BrownSpringAccel.jpg