I just finished my 68 camaro and have been encountering several problems that you guys have been a lot of helo on, Thanks. Anyway i got it running and i thing the carburator is too small. The engine is a 468 with 11.5:1 compression a Wieand Team G intake on top of AFR 305cc heads. The cam specs are 310 degrees adv duration and 264@.50 duration with .590 lift. It is a solid flat tappet isky grind that the RPM range was supposed to be 4000-7500. It runs great up till about 6300 actully it is a little scary on street, and then it falls on its face and wont hardley climb any more. I didn't expect 7500 but i did expect at least 7000 out of it, could it be the size of the carburator. According to the cfm calculators it is too small but it seemed like it would be fine or at least only lose a little power but still rpm. It needs to go farther because i Have 4.56 rear end gears and i wont have enough trap speed when i finally get it to the track. Thanks alot.

It's not the 850. I have run 468s in excess of 8000rpm with one and had no complaints. Does it do it in every gear? If so make sure the valve springs are ok and there isn't something wrong in the ign. system. If it only does it in high gear take a good look at the fuel system.

Yes it does it in every gear. I talked to a guy here locally and he said he thought the cam was too advanced, has anyone had expeierence with this?

List out your entire fuel system front to back.That could be your problem.
Weak or broken valve springs could do that too, what are they rated at?
Are you sure you have WOT?? Easily overlooked

I am running the factory 3/8 fuel line with a holley Black electric fuel pump(140 GPH)up to two regulators. One for the engine one for nitrous when i upgrade the rest of the fuel system to bigger line and pump. Too many kinks to work out before i dare to hit the button. I am running 5 psi to the carb and i am getting WOT. The Valve Springs are brand new Howards Brand 150lbs on seat and somthing like 350lbs at max lift. No flattend cam lobes when I had the motor out due to oil leak during initial break in.
Thanks,
Kyle

What type of ignition are you running?

My ignition system is a mallory hyfire VI CD ignition with the rev limiter set at 7200. I have an msd pro-billit distributer and blaster 2 coil with msd 8.5 mm wires. I am running 18 degrees initial timing and 36 degrees total timing.

Do you have a dwell/tach meter that could eliminate the tach being off calibration at high rpms? I'm not sure but I think the rev limiter starts cutting spark to some plugs prior to the limit to assure it doesn't get passed. Not sure of the numbers. Maybe just try setting the limiter higher for starts. Please don't blame me if the tach was off and pistons go skywards. The advance on the cam I'm not sure about the power curve but I might be backwards thinking advancing is moving your power down lower instead of up into the higher rpms. I'd hate to think it's an octane problem. Oh well. You've got an excuse to hang around a drag strip asking questions.

i do not have dwell meter but the ignition box has a tach test and whatever that is set to the tach reads exactly. does anyone think maybe this is just a bad chossen combo? I have seen the wrong cam kill other peoples performance.

Did you advance the cam when you installed it?

5psi sounds a little low to the carb. and could be starving it... try to up the psi to about 7-7.5 and see what happens. worth a try?

i didn't advance the cam when i installed and i just tried 8 psi fuel pressure. no change.

Valvesprings - pull them off the head and check seat and rate - then recheck install hieght.

IMO

MAT

Do you have the original fuel tank? and has it ever been removed?

The fuel pick ups in the tank had a "sock" screen on then from the factory. If it is still on there, after 30 plus years it will be very restrictive at high attempted flow rates. I would set up a fuel gauge so that you could see it during a run. If the fuel pressure drops at WOT you are loosing somewhere. Either restricted lines or not enough pump or both.