416 jetting

[Nate]

i am building a 416 10.5:1 comp. with an xr400 cam, large intake valves, and i am porting and polishing the head. also i have a complete big gun exhaust, k&n filter, and a modified airbox lid. I need to know where i should start out with the carb. jetting. it is a stock carb.

Stock or dynojet jets??? which will you be using???

[Nate]

i will be using stock jets for right now anyway

[Crowdog]

I've got about the same setup except I added a 39mm FCR. I run at 4500 ft. and moved from a 165 to a 172. Seemed OK, but I don't know how to really tell if it is running a bit rich.

Anyone?

Jon
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[MX MadMann]

if it sputters its rich , if it backfires its lean. keep it between those 2 somewhere.

[deansfastway]

with pump gas @ sea level we use 42/45 pilot 155/158/160 main jet . I also like to grind away the first 3/8 inch off the rear of the carb slide so it doesnt stick so far(obstruction) into the throttle bore.

[MX MadMann]

could you elaborate on grinding the carb slide , like what party are you talking about grinding off?

[deansfastway]

If you remove the carb and look at it from the back while giving full throttle , you will see that the slide protrudes down @ 1/4 inch. We grind thos down to make a smoother transition at WOT . Only the rearward edge and not too much.