After taking alot of advice from various people here on the board to try and solve my problem of my car falling flat on it's face under hard acceleration I put a gauge inline right at the inlet to the carb. At idle the needle was bouncing from 3 - 9 psi and only got worse as I increased the RPM's on the motor. The gauge was a very high quality liguid filled gauge I got from work, so I trust the gauge. My question is what is causing this to happen. The fuel pump is only about 2 years old, and has very little time on it. I am thinking that I need a different fuel pump, what is everyone running on their cars. I need something that looks stock, and has the stock inlet and outlet design. The car by the way is a 70 SS 396. Thanks for any help.

Mat - my fuel pressure does a similar jig, but from 5 to 10 psi. Stock-type mechanical pump. I spoke to my machine shop, and he told me more than likely, when he sees this it means a bad inlet valve. I don't have the falling flat problem, but maybe because I have adequate fuel delivery at 5 psi.

Can you get the car to top RPM OK without full throttle acceleration, like ease it into 6000 RPM without pressing the pedal more than halfway down, and have the car pull good at that RPM? If you can't, it may not be a fuel delivery issue, since it's not consuming fuel at the fastest rate and emptying the bowls, but still falling out. Is there an inline filter from pump to carb, or in the carb inlet? The filter may be clogged up.

The only reason I recommend this method was because i also thought my fuel delivery was junk with a cheapo autozone pump, but it turned out to be ignition. I eased the car into high RPM under light load, and it still fell over. Bought an MSD dist, replaced plugs and wires, and it was like uncorked a monster.

Thanks for the reply, I can't really say if it lays down while easing into it or not. If it stops raining today I will go out and try it tonight. As far as a filter goes, there is a filter in the carb inlet, and I have replaced that already, and even made one run without any filter at all. It made no difference at all. But anyway I will try your suggestion and if it still lays down I will start to look at ignition. Could you tell me exactly you put in your car for ignition. I need to keep the stock look, but need to get this problem solved before this winter hits. Thanks again.

One cheap thing to try before replacing any of the ignition system is to check the resistance on your plug wires. You may have one or two wires that are bad. You'd think that this would be symptomatic at all times, but it takes more power to jump the plug gap when accelerating so this problem can possibly only show up under hard acceleration situation. Regardless, it won't cost you anything to check them with your multimeter.

Has it done this ever since everything was new on the engine? If so, this idea proably won't help but if you are still running points check the points. If your resistor wire or ballast resistor is weak you will burn points in just a few thousand miles (or less). Burned points would likely show up at all operating conditions but if they are just beginning to wear out they could act as you describe.

You could also have a weak coil. If your coil is the original, try using a known good one or a new one (you can borrow my spare for testing if you like).

3 psi for fuel pressure is pretty low, though. You do need to get that aspect fixed. It's almost got to be a weak fuel pump.

Well here is a follow up. I drove the car last night out to a deserted strip of blacktop and ran the crap out of it. It accelerates fine all the way to the top end as long as you do not put your foot to the floor. I tried it probably 6-7 times and it never sputtered until I put it too the floor. The ignition is a newly rebuilt HEI unit, and the carb is a brand new Edelbrock Q-jet replacement. The ignition has no hi-po parts in it, just GM replacements. I scrounged a set of richer secondary metering rods, and it helped a little, which still leads me to believe that it is fuel delivery related. One new thought that I had, was that I do not remember if there is a sock over the fuel pickup in the tank. If there was I know I would have cleaned it, but could this be a problem? I also seem to remember my dad "removing" those socks with a blast of air, am I remembering correctly? And latly what are guys runing for fuel pumps. I want to eliminate that next as a possible cause. I need to keep a stock look, but need a different pump I think.

Thanks

Most people over look the return line on the SS. It will return fuel to the tank at about 5 psi. If the line is plugged or somewhere in the cars history an incorrect fuel pump without the return line has been installed then there is the possibility the excess pressure is "blowing the needle and seat off" and running rich. Check your fuel tank for the return line and make sure it's operational. Your carb doesn't need more than 5 or 6 psi to do the job. Any more will create problems.
Mark

Hmm... if the car makes it to the top of the RPM range fine, it's probably the carb.

For the record, I went with the MSD pro-billet dist, not stock looking at all, so I don't think it's what you're looking for. Another side note - I blew it up in 2 months. :(

I'd look into jetting / fuel metering at full throttle. unfortunately, I know holleys much better than Qjets at this point, so I cannot help much.