I ran very simular set up. Almost identacle years ago and ended up with simular jetting boating out of MI. I had to dig a little however found the old dyno sheets. Bone stock 800 cfm 9022 with the choke horns and chokes. The prim and sec in seq as you stated 79,74 & 86,89. Worked well and ran great. Plug readings were always great. The staggered jetting you have is just a tad more than stock. I recall spending some time to even out the egt's the best I could. As you know and as mentioned every application will vary. The stock jetting was just a little much for my app. When I got the carbs they were very fresh take offs but I don't remember the jetting being exactly as stated although it may have been. Merc may have changed up the jetting a little back then also.

Just noticed my comp was 9.6/1 and had lightenings for exhaust. Your probably boderline or could go either way with intake. What max rpm you plan on running? I was 5,600 - 5,700. On the water I actually liked the single plane the best. I definately pulled harder mid range.

Either way, you'd probably be changing jets anyway. Now you've got the right carb and some good info on a starting point.

Yep - thanks for the advice.

FWIW, I also have an 850 Demon that is brand new. I thought about running it as well. It's not a marine carb, however.

getrdunn, were you running a 496 with dual plane intake, or single plane? Looks like you were set up a little leaner than my carb is out of the box - which would follow logic as the HP500 has a little bit more cam than I have. I have a set of Lightnings that I considered running, but with my exhaust port mismatch (see other thread), I don't think I could run them without some custom collectors. I am not planning to spin this one up past 5200 - 5400. It has forged Mahle flat top pistons and good I-beam rods, but it has the Eagle cast steel crank, so I am going to err on the side of caution. I spend most of my time cruising between 3000 - 4000 RPM anyway, with the very occasional full throttle blast.

Yes, keep the 6.5 PV in the primaries.

Just looking through the stuff I have laying around in the shop, I have an old 850 Holley with 80's on all four corners, and my Demon has 88's on the primary side. Is 80 primary and 88 secondary a close enough starting point?

Yeah, that should be fine. Pull some spark plugs after running the boat for a minute at the rpm just before the secondaries open and check to see how the plugs look. Probably 3800-4000rpms.

After short time in the water I went to the dual plane with a 1" spacer. Thought I was going to have to rejet but never did with an exception of a day here or there weather related.