Need help for friend who is not going to be around long

aengineguy said
Thanks to all for your thoughts...the car was doing the same thing before replacing with a "new in box" pertronix. The engine is totally stock and the new dist. does not have vacuum advance, just one he bought as a spare. I have been thru a hundred Q-Jets and had already checked all the suggested items, pump shot, pump spring, metering rods and piston, etc., etc. My next step which I have not done was to test fuel pressure. It does have a primary filter that is glass, that at idle is flowing good, but have not removed the sintered bronze one at carb inlet yet, will try. It is not a bog, increase throttle from just over cracked at around 40 will cause a surge and sputter and more gas, even to the floor will totally kill power. When lifted, power will come back on. The engine does not die. There is no backfire and timing is dead on.

Ok, this was a very impotant piece of information. These cars were timed differently. I was just very recently involved with a friend's numbers matching 70 SS454 Chevelle restoration. That car was timed off manifold vacuum going to the distributor. This can make a very big difference in ultimate driveability since the manifold vacuum pulls the vacuum canister completely advanced at idle, so it affects the initial timing setting. We had the sho nuff GM factory assembly manual on that car and I remember that. It thew us for a loop as we wee trying to time the car conventionally until I got the bright idea to read the instructions. We also used a Pertronix ignition, but we used one with a vacuum advance, because the owner wanted improved performance, but wanted to remain as stock appearing as possible. So, this "could" be an issue.