Holley 4150 (9381) 830 Jetting
 

I know this is a sacrilege but I am going to detune the 500HP clone in my 22 Classic Donzi to make her more manageable around the marina.
502, 9.5/1, Dart heads, Gil exhaust (Long risers), Crane HP500 cam retarded to 111* ATDC
Currently running a HP500 World Products single plane high rise.
Going to a GM dual plane aluminum high rise.
Currently running 78s and 6.5 power valve in Primaries, 91s w/plugged power valve in Secondaries.
Sea level
Does this jetting sound about right for the dual plane?
THANKS!

Watch how #3 colors with that intake as its about the leanest cylinder, 2 will be rich, no way around it, ignore 2 if doing plug readings, Smitty

What sre you having problems ‘around the dock’ with, specifically ? Maybe just a carb or ignition issue ? I know the non marine 830’s can be pain in azz to tune for some reason. Marine 800’s like that came on hp500’s are straightforward. Once those are fixed/tuned correctly Can even mellow idle out more between shifts with a Daytona Sensors box probably.

Are you interested in parting witj the singleplane intake? If so, how much?

Best me to it.

i assume your talking gms copy of a edelbrock performer rpm intake, if so, thats a GREAT intake for a 502, you'll see a 20 to 40 or MORE foot lb of tq increase in usable powerband at the sacrifice of 5 to 8 hp from 5500 to 6000 that most boaters never even reach. I discourage my customers from ever single planes on 502s and smaller unless they want to pump compression to octane limit, put a huge cam in that also sacrifices tq and spin it 6k, Smitty

THANKS I will check #2

https://cimg6.ibsrv.net/gimg/www.off...941f287feb.jpg
Idle too high or she loads up. I will look into Daytona Sensors
Plan on keeping it.

Yes, similar intake. 5800 RPM motor but usually prop for 5600. PLENTY of torque for a 3800# boat. I don't mind a little off the top end if it will keep people from shaking their fist at me in the marina ;)

THANKS, for the help guys!

I've dynoed 502s with both, a perf rpm makes significantly more power thru 60 of power band, about same power for next 20% and gives up 2%hp on top unless your talking 10, 10.5-1and a cam in the mid 240s or bigger for most part.. we made 640 hp and 625,630 tq are (open headers, no accessories) w perf rpm, afr 305s, Bob m cam , 850 holley and 2" of carb spacer. 26 ft liberator it went in has broke 80mph mark gps with good air and low fuel fwiw.