Wont pull hard on top

I had the car out the other day and it didnt pull like normal up top. I had set the carb a few months ago when it wasnt this hot or humid. It ran fine and pulled hard from the lower rpm range but when it got around 5800 or so it tapered off and wasnt revving as fast and it felt like the power was falling off. It was still pulling but this car usually pulls very hard in the upper rpm's. I usually shift around 62/6300 and its still pulling.
I havent checked anything yet and havent had time to drive it either.
anything come to mind ?

what do you have under the hood?????

470" b engine. mopar performance 383/440 aluminum heads .590 cam M1 4500 flange with a 1050 2" tti's 10.5/1 34deg timing no vac adv. chrome box four speed

I am thinking it may be either an ignition problem or the carb, maybe it was just because it was real hot and humid and I havent reset the mixture screws on the carb since this spring?
This carb (1050 model 8082) has never been great, but has always worked o.k.

not enough advance. try 38*

it was working fine the way it was set, I will add a little timing to it.
I think my fuel pump setup may be the problem.
I am going to make a change in that area when I pull the rear out for some new gears.

Your not getting valve float are you?
Mike

I dont think so but I dont know, how do you tell. everything sounds fine and I never did before. I had my springs checked by a machinist when I had all the engine work done. I have recently checked all the lash and its all in spec and the same as assembled .024/.028 cold.

As stated 34 degrees (max for a small block) is a tad low for a big block.

Did you check the plugs after you took it for a blast

Do you have a choke and is it opening?

Are you not getting enough fuel at higher RPM for some reason. Fuel filter restriction etc

You mentioned it was not as hot when you tuned it. The colder the air the denser the air charge charge, as you start to lean out you can make more power.