axapowell

Here's the deal:

509ci NA 9.25:1 compression
AFR 315cc (305 cnc'd) Heads
Crane 741 (168741) Cam
Crane ignition Hi6M
Dart 6200 Intake (HP500)

I am changing out the stock Holley carbs and fuel system. -8 line all the way from the tank to the carbs, new fuel water separators (3/8” to -8 npt bigger openings), Keith Eickert Fuel Pump 120 GPH upgrade and Barry Grant Mighty Demon Marine 850 carbs.

I already know that this is adequate to feed the power.

Here are the questions:

1 – I need a baseline, or a place to start, for jetting. Do I stagger like I did on the Holley’s or do I just start with the standard 85p 93s and go from there?

2 – With so many people talking AFR’s. I purchased a FAST system and have had my tails bunged. Looks like the numbers should be:

Idle 13.4 to 14.1
Cruise / light load 13.6 to 14.1
WOT 12.2 to 13.5

Real life numbers would be great, no need to speculate here as I can do that all day long myself. If you’ve ran a similar set-up, great! That’s who I’d like to hear from. No blower comments, it’s Naturally Aspirated. Thanks in advance!

Dave

klaw

I will dig out my dyno sheets tonight I have a setup similar except for the heads. Got 565 on the dyno will be interested to see how much more the heads do over stock 500 hp heads ported

axapowell

Anybody?

Dave

jeff1000man

No it isn't. Los of differences in the way a demon works.

I for one really hate them.

axapowell

Is anyone running Demons on a N/A boat? I'm really surprised. I know the 850's can flow up to 1000 cfm, just still wondering if I should stagger the jets.

Thanks,
Dave

thumper038

iTrader: (1)

I dont know of anyone using demon carb on a boat.
Merc uses holley on all perf products ???

Is it a merc manifold with the PCV valve in it?

To stagger question Merc sets them up safe and staggerd.
I am sure you know this = but 8 egt's on the dyno is the only way to tell for sure on each cylinder / stagger question.
Your one per side a/f ratio will keep you safe but not perfect.
Find a good dyno shop and spend the money on one at least one to know.
My 2 cents
Thumper

jeff1000man

Demons in my experience work really great at WOT, but they suck everwhere else.

thumper038

iTrader: (1)

I concur Jeff
Me no like the Demon
Thumper

niceguy

By u boy has one on his n/a BBC.

jeff1000man

I have had to float around in Lake Conroe with that busted Demon in that boat also.

Ask him who rigged it so that we didin't crash into a bulk head