Dan, Like you said, if you checked the plugs after a high speed run cutting the ign. then WOT looks good but according to you the midrange is where you had problems, so good point!

FYI, I installed a carb Hat on my procharged boat and was up on Lake Charlevoix tunning, turned the key off at 3500 cruise speed, pulled a few plugs and almost $hitt myself, but WOT was low 11s on one bank and high 10s on the other. messed with it all weekend (suppose to be a vacation) Ha right.

You ever see the dyno video where they kept turning the carb hat to tune the engine banks, lean vs rich? It was amazing to see that how the air entering the carb could alter the tune bank to bank.

I remember seeing that on my buddys procharged build while dynoing. If i recall, the hat entrance was on the even side , and the odd side cylinders were significantly richer

Probably a lot more air went thru those boosters causing much more fuel to come out of them.

Plug reading has to be done on a hot shut down, its not fun in the boat. Here's a good reference for plug reading;

That’s the best advice anybody could ever give you right there. Damm I remember 30 plus years ago that’s all we had for the most part. PLUG READING. I would always be checking the hotter cylinders at cruising rpm’s and wot. We didn’t have all the fancy chit then nor could afford it. It was school of hard knocks. Dan that video is priceless IMO. Don’t feel bad about what you may not have known before rather learn from it and move forward. So many people are clueless when it comes to plug reading/tuning. Like whaaaaat?

If you think about it… Do you ever hear of anyone talking about the perfect plug burn and timing? Ah hardly ever! It’s always my afr’s or my egt’s. In fact egt’s almost seem to be less and less of a reference. I still have an old ancient egt probe and digital gauge I use to monitor #8 on some blown bbc’s.

I’ve said it here before but will again and on those same engines the egt’s were like melt piston hot but the plugs told me different. Had to lean it way up to get the fire back in the hole so to speak - Resulting in much lower egt’s. Like the video mentioned there all just numbers at the end of the day.

There you go!!! Thank you! I missed some earlier post. 👍👍👍.

I’ve still got burn marks from doing in the boat from years ago. 😂

No I haven't but now i must see it just to learn, No need for me any longer as I re-installed the Carb boxes and put the jetting back to where it was for years, and realized a few more HP is just not worth the lose of reliability and ease of usage. Another experiment that didn't pan out for my needs.
But what else can we possibly be doing with ALL are SPARE time?

Currently have 8.3's (510R's) on Sterling 1100's. Maybe 10 hours on motors since on the dyno. First experience with 8.3's. Previously had 8-71 and 10-71's with 120 rotors. 8.3's run great but at idle (1000) they seem to make a bunch of racket. Belt tension varied between 1/2 " to 1" cold but no change. Backlash in rotor and input seems ok. Maybe I am being too critical? Anyone else have any experience with this?