What size jets should I use on my 414 stroker? Carb is a Proform 750 with mech secondaries, currently has 84/78 jets in it. I haven't ran it yet, as I'm still assembling the engine. Here's some info on the engine:
360 +.060
4" Forged Eagle crank
Eagle H beam rods
KB 745 step dish forged pistons with .030 milled off step.
10.0:1 CR
Iron Ram heads, fully ported by Hughes with 2.055 intake valves.
Hughes Cam 237/242, .584/.592 lift 108 LSA
RPM Air Gap, port matched.

Going in a '74 Duster for strip/some street.

Thank you.

I'm guessing you mean 78-84. I'd try that for starters. Probably could use 31 squirters, and a 6-6.5 PV.

I have a Question??

Why do people want to take a carburetor properly calibrated (jetted) from the factory and go up or down in jetting before even trying it???

Guess carbs should come with no jets and instructions that state get the expert down the street to determine how much to over jet you carb!!!

What's the proform set up sheet recommend, jetting recs are on the instruction sheet for the main body.

You'll need a larger carb to get the best out of that engine is my guess.

What is the carb number

I just found the spec sheet on it online. Comes with 74/84 jets. The guy I bought it from said it had 78/84, so either he was wrong, or the primary jet was changed. The squirters (original) are #31. I guess I'll try it as-is.

This one
http://www.proformparts.com/mistore/Wcbdcafc9f82b0.htm

or this one
http://www.proformparts.com/mistore/Wce00621b4333c.htm

My 408 seems real sensitive to the intake style. My 750 dp has been jetted from high to low 70's in the primaries- higher for single plane/ open spacers, and lower for 4 hole dual plane. I think I have like 72s and 80s in it now with rpm air gap and 4 hole 1" spacer. Still not done tuning but it drives pretty good.

A carb that is probably jetted for one application will usually work just fine in another application. We move carbs all the time from 500 hp motors to 800 hp motors on the dyno and the motors run just fine and they have the correct AF ratio.

A carb is designed to self adjust across a fairly wide range of inputs. So if it is installed on a motor that uses more air then it will also meter out more fuel and everything should be fine.

thats because the engine pulls in air and that air brings gas along with it dependent on the venturies, metering orifaces and so forth. a bigger engine may need more gas when its running at higher power levels but the valving in the carb will still put the same gas to air ratio and if anything, would just slow the engine down somewhat as the bigger motor needs more fuel which the smaller carb might not be able to supply. the only tweaking would be minor adjustments for idle due to vacuum differences and wot if the carb is too small

jetting should be individualized for max power on any engine. internet suggestions should be starting points and not gospel cause you wont have the same intake system from aircleaner, carbs, manifold to heads