its in a bottle and fed into the engine by 25 jets and that is just the nos side..

He tried them. No change. When I put a vacuum gauge on the carb adapter under the carbs, at 3500RPM the carbs are seeing 8-9" of vacuum. At 4000, the vacuum drops to zero. So in that 500RPM window, pretty much any powervalve will either be closed, or open.

So measuring the jets it appears to be .001 difference between jet sizes.
I put a .013 wire in the powervalve passages, lets see what happens.

wonder how far that would go in a single engine boat before it ran out of nos,or puked the drive?

i dont trust those jet charts or the number on the jets ,,i always use a pin gauge and at times i will correct the sizes with jet drills..

Anybody have knowledge of blow thru's? Don't mean to hijack your thread Dan but considering the turns this thing took already didn't think you'd mind.

I'm trying to figure out a stumble that almost always happens when the power valve opens. This happens at all loads, RPM's and any power valve used. I was going to change out the power value restrictors but my $1300 Carb shop carb came with less than the desired bleed type screws. Time to get the drill. Also, I can only get 1/2 of a turn on the idle mixture screws before it goes way rich at idle.

I was thinking or starting with the idle feed restrictors since opening the idle bleed really didn't change much. After this, and getting at least a 3/4 turn on idle mixtures screws go after the power valve restrictors. Any thoughts?

Yes, I know this is a car. but the Carb Shop guy is useless. "Didn't do it on the dyno"

on blow through you need jet extensions on the secondarys,,also see those 2 holes under the power valve,,those need to be slightly opened up if your jet is above 88 in size but dont go crazy..

What size are your pcvrs? And are you running a high flow 4 window powervalve?

sounds like the power valve channels may be the issue as well, try to find some stock holley metering blocks and swap those for a test....will know quick...Rob