Pontiac 400 quits at about 5000 RPM

[dobie6982]

After trying to find the limits and then push it beyond that, I am having trouble getting past 5000 RPM. Its like it just hits a wall, it doesn't bog down or giving any indication of a problem, it just quits then will slowly go to 6000 RPM which is where I am trying to shift. It has plenty of power up till then, like I said at 5000 it just stop accelerating. The stats are listed below.
1973 Pontiac 400
Forged rods and pistons
Edelbrock 750 Carb with stock jets and number 4 springs, 073x042 rods
Edelbrock RPM intake (stock)
Edelbrock D port heads, ported flows 315 CFM
Summit Racing HEI distributor
Comp Hyd Roller Cam Duration at .050 230 I-236 E Lift with 1.5 rockers 510 I 521 E

Pulling about 9-10 vacuum at idle.

I am looking at changing the distributer springs in the morning.

Any of you guys have anything else I may want to check out?

[NOT A TA]

Fuel supply? What pump are you running? Filters?

[Taman]

I agree. Sounds like you are running out of fuel. Pump not keeping up. Need to know the fuel pressure under load at that rpm.

[dobie6982]

Never even thought about fuel pressure. I am running and Edelbrock that is rated at 110 gph.

[NOT A TA]

Will the car spin up in 1st gear? If so, I'd look for a restriction in the fuel supply like a plugged pickup sock or kinked line that would reduce flow. Do you hear a sucking sound if you open the fuel cap right after shutting off engine?

[4mul8ion]

What about the air cleaner? Are you running a shorter air cleaner with the RPM manifold to clear what I'm assuming is the stock hood?

Kevin

[72blackbird]

You may need to upgrade the fuel line as well- a stock 3/8" fuel line may not be large enough to supply a 500 hp combo.

Geno

[Parts Abuser]

What's the A/F ratio at 5000 rpm? 3/8" fuel line will supply 500 hp; there's not a lot of head room, but it will provide the fuel. What's the ignition timing at 5000 rpm?
Thanks,
Vince

[Parts Abuser]

Just reread your post. What does your exhaust consist of? Header primary dia? Long tube or short? Dia of rest of exhaust? Any kinks, etc? With your cam, heads, etc., this thing ought to shoot up past 5k toward at least 6500 before flattening out.
Vince

[dobie6982]

Ok so I put the gold springs on to take some timing out. I ran it out and did great through about 3rd gear. I am now with most of you on it being a fuel issue.

Parts abuser , I am running hooker comp header with 3 in collectors and 2 1/2 the rest of the way back.

I am running a standard K&N 14 in air filter.

I am going to check the fuel filters and lines tomorrow.

[alphaenvirmgt]

Valve springs fresh?