Ok, this one has me pulling my hair out. I'm open for ideas on what to try next.
Basics
2.4 200 83 block
wh22 carbs
holley red pump
aeromotive regulator
at high rpm, exactly 7k it seems every time it falls flat on its face, boat noses over. If you keep your foot in it a moment later it will snap back to life an pull clean to 72/300immediately. Fall over again, snap to 75/600 immediately again and fall over. I get out of it at this point because I don't want the boat nosing over going even faster.
This is a recent issue that has come up once I started testing with shorter props and race gas. The first time it nosed over at 7 I suspected had jetted down too much and never stayed in it. I kept going up in jet sizes until I got back to my fat cruising pump gas jets and it never changed. That's when i decided to keep my foot in it and see what happens.
This was with a 20p drag prop. The same boat has turned a 30 to 7800 and was still pulling when I let out.
I have not put a big wheel back on to see if it does it with it again or not. I suspect it would, I had some mid speed stumble that was starting to show up every now and then before. I suspect what ever is causing this was causing that.
But it could be perhaps its accelerating so much harder with the short wheel the fuel demand can't keep up.
Anyway in testing I have also developed an off hit stumble a few moments after you punch it, not when you punch it but right after its up, and it's very quick. Nail throttle, pulls out of hole hard, stumbles for a fraction of a second and pulls clean to 7k the. Stumbles again.
I have changed jetting from 78/80 all the way up to 84/86 with the Same stumble everywhere. No difference
raised float bowl height thinking it might be draining the bowl too fast, no change
cleaned and inspected fuel filters no change.
Checked compression and leak down, all good.
Checked stator, switchboxes etc all good.
It has become extremely hard to start for the first time of the day, after that look at the key wrong and it barks off, was never this hard to start before
cleaned and inspected carbs, rebuilt with new gaskets, new needles and seats.
I suspect a fuel dilevery issue at this point but I'm out of ideas.
10an from sumped tank to 10 micron filter, 6an from filter to pump, pump to reg reg to motor and reg to return
adjusted fp from 3-7 at 1/2lb increments. No change.
The pump is new, but I'm starting to suspect it. I have a blue I can swap out to eliminate that issue.
Any other thoughts?? Seems like I've tried all the things I can think of at this point??