First of all I'll give you the basics: 383 stroker done the old fashion way (not by me, but I got it like this), 68 327 block .030 over with a turned down GM 400 crank with new pistons (zero deck height). 64 #2461 fuelie heads with some porting and port matched to a Team-G intake with a Holley 750DP mech secs. with 76 pri. and 84 sec.(originally 71 pri. and 80 sec.) and a 6.5 powervalve(tried an 8.5-4.5). 1" phonelic spacer and a heat shield. Cam is a .525/.525 lift and .248/.248 dur., and has solid lifters. Valve lash is at .022 int. and .024 exh. with 1.5 int. and 1.6 exh alu. roller rockers. MSD digital 6 ignition, MSD locked out Pro Billet distributor, MSD 8.5mm wires and a Blaster SS coil. The plugs are AC delco R43. with a .050 gap. Engine has 10" hg at 850 rpm in gear. SFI rated flexplate and balancer. Edelbrock high flow water pump

The problem I'm having is the engine stops making good power at 5000 rpm and just falls flat till I decide to shift (TH350 with a TCI full man valve body and a 3500 stall), which is usually around 5500-6000. Also at random times it stalled out and stranded me for 15 minutes till I let it sit for awhile and then had to full throttle it while cranking to get her started again. I put in a vented rubber hose attached to the vent tubes to prevent any fuel from spilling into the carb and causing a rich condition when G-forces are introduced too. I've tried ALL the obvious things and actually I just got this new MSD dist and still the same. I used to have the GM HEI unit w/ vac adv can and a Blaster coil. I've went up and down with jets, advanced and retarded timing, tried diff springs, w/ and w/o the spacer, stock coil and everything. The reason I went with a locked out unit is I had a jumpy timing mark due to a loose distributor and I thought it was a miss or a bad wire. Now with the New MSD dist it is dead on at 34 deg. BUT.....it does advance a little if I bring up the revs to about 3000rpm(about 1.5-2 degrees. I know the MSD ign doesn't have the multiple spark thing happening after 3k but you think mabey there is something wrong there? I am now using the start retard feature that retards the timing 20 deg until she gets up to 400 rpm. I've tried without it too.
I set the pri and sec idle adjustment screws and that got me in the ballpark for a stable idle.
The powerband seems a little narrow for the parts that are on it. I know the heads can flow up to at least 6500+ in stock form with solid lifters but where's the power. I also know that when you stroke out an engine you gain torque and loose topend, but this much?
The only thing I haven't done is a compession test on the cylinders because the tester I have is VERY difficult to install into the sparkplug holes with the Hooker super comp headers (w/sidepipes). The cam was already in(good) used condition when I got this engine but the pistons and rings were new. There was a concern that I didn't seat the rings enough during the tuning phase before I got her on the road but have been putting her hard to work ever since. This problem was there from the beginning but I thought I just needed to tune it out. I even had her on the highway a couple of times for like 30 minutes. She smokes a little when hot at idle but seems to clear quickly, Maybe a rich condition due to it being black when I rev it hard. Like I said before I've had it lean with 67 pri and 76 sec with no resolve on hot days and cool nights.
Any suggestions will be welcome at this point before I break down and bring my baby to the local speed shop. They do have many years there and do a lot of work on Vettes so I trust them, but being a Broadband Data tech at a communications company and an all around mr fixit I would like to solve this in my own garage like a real mechanic.
P.S. Here are two videos I made showing how the car performs right now. One shows the power limit (might want to brighten your display properties to see the tach) and the other shows what happens when she hesitates and wants to stall.


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Flat at 5000-Could it be starving for fuel,I didnt notice where you talked about the fuel delivery.
The stalling on turns sounds like fuel level too high.

 

The fuel pressure and level has been played with many times but to an extent that I might have to go further into the extreme numbers to see when it really messes up. My only fear is that this seems to be a rich condition and I'm afraid to go too lean in the process of trial and error. According to 2 different gauges, I got 2 diff pressures and I don't know which one to believe. Was set between 5-6 psi on a cheap gauge that mounted right into the fuel rail and then when I installed an Autometer (w/ isolator in car) it was immediately at 8-9. But the Autometer never went to 0 when off, it stayed at 3psi. I even tried to bleed it several times to get it to 0 and ultimately set the psi at 6.5. Fuel level is fine (just barely dribbles out the hole) at both high and low pressure settings so the high setting is not blowing the needle and seat, maybe I should keep it at 8.5 psi and go from there? Maybe the gauge is off?

 

When you were making your turns and the engine began to stumble did sound like a rich condition.As though fuel was sloshing over and trying to drown engine.
On the running flat at 5000 I could not actually hear it but if its running out fuel due to lack of flow to the fuel pump starving on the pump side.Like the line going to the pump is too small or the fuel sock in the tank is plugging up or the tank is not vented.Watch your fuel pressure at 5000 and see if it begins to drop off.

 

Yes the pressure begins to drop around 4000 on hard acceleration, but I removed the fuel filter that was inline before the pump near the tank that I put there to protect the pump and the element became detached from the housing inside. It was glued somehow on one side. I just had to open it when I heard a rattle in there. I now have a temp junction there for test purposes. I don't think there was that much restriction there but ya never know. I'm not running a fuel sock at the inlet, I removed that when I installed a new sending unit. I also replaced the 6.5 powervalve with a 4.5 because vacuum is real touchy even when just stabbing the pedal in neutral, when driving under a load it drops quickly before building up again. The #8 and #1 plugs look a little dark but the rest are perfect so the sec jets seem to fine, I just have to get another set to get an accurate up-to-date reading now that I have made some changes. It was raining here tonight when I got it done so I will test it tomorrow.

The time I was making those turns and the engine was running rough were due to the lower rpms, it was doing that even when stopped and I barely made it home that time, had to keep some throttle on it when stopped. Besides, like 2 weeks ago I already made a vent tube apparatus and connected them to the vents on the top of the carb to catch any fuel slosh.

 

I would check the fuel flow on the pump.Put the outlet hose in a bucket and turn pump on for say 10 seconds.Measure the fuel.I would say it should be no less than 24 oz.Check that spec.with the manufacture of your electric pump.
On the sloshing -I'm talking about internal flood over not fuel coming out the vent tubes and going down the carb in the air cleaner opening.If the level gets too high for some reason it can start flooding over inside the carb before it comes out the top.

 

I got the Holley (Blue) pump rated at 120 gph. Well I went for a test drive after yesterdays adjustments and without that busted fuel filter it now makes alot better power to 6000 rpm. Along with removing that filter I reinstalled the stock pri jet (71) and threw in a 4.5 powervalve and let me tell you my baby is finally starting to shape up. I left the secondary jets (84) in there along with the 50cc pump because it still feels good into the transition and hangs it out on the topend without black smoke. Also it's not smoking when I rev it up in neutral anymore, even when I get into the secondaries. I still have some fine tuning to do and will post updated material here when I come across anything. Thanks.

 

Have you checked to see if the heat riser on the exhaust system is functioning properly? If it gets frozen in the "closed" position, you will end up with similar symptoms.

 

Don't have a heat riser setup, I got Hookers Super Competition Sidepipes. So far it ended up being a defective fuel filter inline before the electric pump.

 

You must be running a hydraulic cam! Solid lifter engines don't stop at 5K

 

Plugged up fuel filter and/or pinched fuel line would do it. I hope [for your sake] it's that easy.

 

I hope your kidding. I actually resolved the issue. Here's the my post on it.

And what I was refering to was the feel of the powerband at certain rpms. I can actually rev the engine to 7000 rpms but it wasn't performing the way it's supposed to. I have a hydralic cam in my van and I know what valve float feels/sounds like. Plus a .022 valve lash on a hydralic cam setup would rattle like crazy.