Diagnostic help ..

[elwood]

Hey guys, Kinda of a long winded story, but Ill try to keep it short..
I have a late style Merc engine, It runs great, so I couldnt help mess with it,
It had a Finton 2 carb intake with a alternator, with 2 Holly 2110s,
Stock cam, Mallory Unilite, and a MDS 6200 series box.
Well I put a 400Jr cam and a Eddie Meyer intake on it.
Isky single spring, springs and adjustable lifters, and changed the alternator to a generator .
If you drive the car under 28 to 3k RPM it feels great, but right around 3k it acts like its hitting a rev limiter .
I rebuilt both carbs and have the fuel pressure set to 5 pis .
First I thought the coil was breaking down, so I changed it, same thing.
Then I disconnected the MSD box, and the unilite, and stuck one of Jims distributors in, same thing, battery is good.
I actualy spoke with Mr Iskenderian and he said the 400Jr should work with his single spring set.
Im thinking the valves are floating, I dont know what the valve seat pressure is, not sure how to check on a flathead.
I feel certin its not the ignition or fuel, what else could it be ? Valves floating ?
Thanks ...