350 spits and sputters under load

[wbulick76]

The 350 in my Skylark runs great at idle, revs up nice, plenty of power. As soon as you put it in gear with your foot on the brake, it will start cracking out the exhaust. I have tried the following-new HEI distributor, cap, rotor, coil and direct 12 volt power supply to test, electric fuel pump, and a different carb. All made not even the slightest difference. Any ideas? I am at wits end!

[Yogi442]

HEI with vacuum advance?

[Yogi442]

is it an HEI unit with vacuum advance?

[wbulick76]

Got it fixed! Turned out to be the one thing I had not changed, and that was plugwires! Very deceiving, as they looked almost new! Changed those, and good as new! Thanks everyone!

[jwc191]

yes, thats one thing to check, when i bought my 75 lesabre conv last year, it was running rough, with only 41,000 miles. did a complete tune up and the wires were original, stamped 1974 on the wires, what a differance.