I have a 355 I am looking for some help on. I have 2 new carbs a holly 670 avenger and a quick fuel 750 slayer I have tried the both and have to pick one to tune in. The holley runs better out of the box but it is a little lean the QF is way rich both are VS and setup the same which one should I run?
My combo is a 355 10.1CR
Sportsman II heads milled to 66cc light port work 2.02/1.6
XR276HR cam .502".510" 110 lobe sep 224/230@0.05
Performer RPM intake cut bridge

timing set at 12 initial 35 total no vac adv
vacuum looks a little low at 8" the power valve has been changer

any tips will be appreciated Thanks Tyler

 

also it has 700r4 2700 stall and 3.42 gears.

 

i would start by giving timing a little more mine is about 18, then use the 750 you have enough engine to benefit. use sofas sticky in this section its pretty good. i have a similar setup, more gear and tq converter though. i have the big jet kit and still ended up buying a few sizes below for the primaries. like 65ish i think it 70's or so from the factory. jegs has them on ebay for 5 bucks free shipping. my carb is a 4150 mech secondary so someone else have to suggest what they did.