1970 Lemans 350 4 speed

Asked by GuruCH84N Mar 31, 2019 at 05:32 PM about the 1970 Pontiac Le Mans

Question type: Maintenance & Repair

My 1970 Lemans intermittently bucks during acceleration.  So far I have changed plugs, wires, distributor and rotor, gas filter, and most recently I replace the carburetor with a brand new 600 Edelbrock. After changing the carburetor the engine definitely runs smoother, and the throttle response is much better. However the bucking problem still persists.  It does not happen all the time out when I take the car out for a drive it will happen within 15 minutes.  Once it happens if you take your foot off the gas the bucking stops but if you reply the gas the problem may or may not reoccur immediately. Oh forgot to mention the the car has an electric fuel pump, Mallory distributor and MSD 6201a ignition. Any ideas?

3 Answers

271,595

Check the timing and the ignition points (if you have points).

Thank, I do not have points. I will check the timing but if it is a timing issue I would expect this problem to happen all the time. Any other ideas?

14,175

When was the last time you had the fluid in your dif checked. I had a similar problem in my 5 speed Trans Am. Fluid in the dif was low. Added some and problem disappeared.

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