I’m with you! lol Just tired of spending money!

I’d have to run a fresh set of plugs because these have been through it. Dark but from fuel. Even bank darker than odd. No pictures but next time I go out, I’ll have fresh plugs and I’ll take pictures.

I put the data into a graph… interesting to present it that way because the fuel curve can be visualized. For me that helps. Have been doing a lot of reading tonight and I think that there are a couple of things happening:

1. Down low, the IFR is still too big. I made some 33 and 34 IFR jets so I could give those a try, and if needed, I might be able to lean it out just a little with a 71/72/73 bleed. That could fix the fuel curve on the bottom.

2. As rpm goes up so does the A/F. Demons do run some serious jet due to the venturi and booster setup (so I’ve read). Next thing to try would be some smaller main air bleeds, 24 or 25.

Once the curve ends begin to flatten, I can mess with the jets more accurately. That’s the thought anyway.

Tom,
For reference my Barry Grant 4150 carbs on my old 590HP 454's ran 76/82 jetting with a 6.5PV, they flowed 950 cfm and ran an AFR of 12.2-12.8 with your existing cams.
I'd put a couple new plugs in convenient cylinders and go run it.

crazy how some want lots of jet and some dont to achieve afr target. Do you remember size of your PVCR feeds? and bigger question, regular bowl vents, j hooks or this newer bridged holley vent thing? I just installed one of these on a 850 carb on dyno and afrs went down a full point, had to pull all kinds of jet on a 600 hp 509.

Willy’s vent ?

I'm no expert in regards to jetting but they seem pretty high to me.
With all you've been thru already I hate to bring this up, but have you verified you're maintaining fuel press at high RPM?

[QUOTE=zz28zz;4898278]I'm no expert in regards to jetting but they seem pretty high to me.
With all you've been thru already I hate to bring this up, but have you verified you're maintaining fuel press at high RPM?[/QUOT theres a big difference in jetting between J hooks, regular vents and the "truck" vent I just posted, 10 years ago I wouldnt have believed it, thats why Im curious what kinda vents he has

something a customer just bought for 2 engines Im dynoing, says to be a holley part #

[QUOTE=articfriends;4898282]This makes sense cause the J-hooks would produce a slightly neg press in the float bowl due to venturi effect, where-as the straight vents and the bridged thing would have a slightly pos press in the float bowls from the ram air effect.

My comment wasn't directed towards the vents, just a general comment abt leaning-out at higher RPMs.. I went thru a similar situation when I first got mine. In my case tiny strips of teflon tape (from prev owner's handy-work) got caught in the fuel pump check-valves so fuel press dropped at high RPMs.

in a way this goes to my point of the hatch being off. on a dyno the air is straight down to the carb, in the boat with the hatch off the air is a big whirlwind of crap. in the case of the modified boat the carbs had regular straight vents and the air thru the arrestor was so fast that it would draw fuel out of the bowls. seems those vents would negate a lot of the straight down air or cross air or what ever the carb is seeing at the time.