Edelbrock Carb Jetting for 440 - lessons learned

[Mosin]

Just to potentially spare someone the time/headache/s:  Edelbrock makes two Performer-series 750cfm carbs, the #1407 and #1411. The 1407 has a manual choke, and the 1411 an electric choke. For that reason, many classic Winny owners opt for the #1411 to replace their electric choke Thermoquads, as I did. Beware: the 1411 is factory jetted "for economy" which means it is jetted way lean compared to the 1407. In fact, the two are jetted so differently that the calibration charts in the Edelbrock manual don't even overlap (meaning the richest #1411 setting isn't even on the lean side of the #1407). I was experiencing stumbling, hesitation, and a lean condition until I made this connection and fattened up the mix. I am currently running my Edelbrock #1411 with configuration #21 on the Edelbrock #1407 chart... that is .113 mains, 073x37 metering rods, with .110 secondaries, and stock orange (5lb) step-up springs. The difference is amazing! Now as for my MPG...

Cheers,

Dave

[Oz]

I've been running the 1407.  Another note with that from Sea Hag is that the 1407 requires buing the orange spring and replacing the blue one.

[Mosin]

I've been running the 1407.  Another note with that from Sea Hag is that the 1407 requires buing the orange spring and replacing the blue one.

I could be mistaken but I believe it's the other way around. The 1407s and 1411s come with the stock 5" orange step-up spring. You can purchase a spring set separately, or calibration kit #1489, which comes with a complete set of springs (Blue 3" ; Yellow 4" ; Orange 5" ; Pink 7" ; Silver/plain 8") as well as jets, rods, and rod clips. I tried all of the spring combos and ultimately went back to the stock orange 5". NOTE: The paint comes off the springs rather easily so be sure to pay attention to which is which (the #1489 kit comes in a plastic container with various wells to assist with organization) as your stock "orange" springs will look "silver/plain" when you pull them out!

All the best,

Dave

[Oz]

Yeah, I could have them backwards.  I was going by faded memory. 

[BrianW21]

Installed a 1411 edelbrock two weeks ago and found the same thing you did, she was jetted very lean from the store. In fact lean beyond the point of combustion for anything other than idle. I had the exhaust shop install an oxegen sensor bung so I sould put my wideband on and see what was going on.

I took your advice and went with  .113 Main Jets, and 73x37 rods and moved the old .110 jets to the secondaries. Using my wideband I checked the resulting A/F, and found that while this did fix the "power side" (low vacum) of the equation, the cruise side (high vacum) and WOT (secondaries) are still off. I used the 1489 kit to make your suggested changes.

From my Wideband (at 3200 feet).

Cruise Mode is running around 16:1 to 17:1  (I can feel a stumble)
Power Mode is running around 12.8 to 13:0
WOT is running around 14.5:1

I am going to order the other jet kit, and work some more on this to get it where it should be. I think going another +8% - 12 % on the Cruise, -4% on the power, and maybe a step up on jets for the secondaries.

As workaround I went with the pink spring so that she drives in power mode most all the time, but really we should be using the Yellow spring so that she stays in cruise mode at 65-70 on the highway.