Warmed up the drag car today and focused on my Innovate A/F ratio meter.  I have it set to read lambda, so 1.0 is 14.7 gas A/F ratio.  At idle and warm up, the gauge reads 1.1 -1.2, occasionally blipping into the read "Lean" region on the display.  Running up to about 2k with no load, the A/F ratio is nominally 1.0.  Then I foot-braked the car and held the engine fully loaded as much or more than the brakes could hold.  The A/F ratio was fairly steady at 0.70 (10.3).  Video doesn't appear that I'm trailing black smoke, but I think there may be more power to be had.

I know that you're not supposed to tune to a number, but it would seem that I may be fairly fat on the main jets.  Seems like around 0.85 (12.5) is generally where engines make the best power, so I've read.  Would a four-number decrease be a good start?  The carb is a R-9375 first generation 1050 dominator, current jetting is 93 (f) 94 (r).

Thanks for your advice!

New in the original package Edelbrock FE Ford bare cylinder head.  Performer RPM Cylinder Heads Chamber Size 72cc Bare Single 61-76 Ford 390-428 Cobra Jet Polished

Just have the one, save some over Summit, asking $500 plus shipping.  Email me at dajameson427 at hotmail dot com

Assembling an engine for my 66 F250 that will be used for towing and some cruising, no racing.  Block is a std bore 427 with a 4.25 crank setup, for about 480 cubes.  Compression ratio is right at 10:1.  Block isn't drilled for hydraulic lifters, so I'm trying to spec a solid cam.

All the cam recommendations seem to be for 390-428 size engines, with durations starting at 224, 230, 236, 240...., with LSAs at 110 for the smaller cams and 108 for 240 on up. 

How much more duration should the cam have to account for the additional size?  I'd be looking at the 224 duration if it was a 390, but the extra ninety cubes should make a difference.

Thanks for your input and discussion.