Poor preformance at highway speed

Alright....I said I was going to post more on this problem I am having with my '70 280SEL and here goes. When I get the car above 50 it starts to jerk a little bit and it sometimes backfires. I am not sure if it is a fuel mixture problem, an injector problem, or what. I know it is not the timing or dwell angle because I have set, reset, and double checked that. Combining that problem with the burning of oil (about a quart to every 500-600 miles), and I don't know what I have on my hands.

The engine is strong, and runs really well until I get to 50mph. The car idles and runs like a champ, but I am afraid to drive it too much, or take it on the highway until I can figure out what is wrong with it and fix it. If anyone has heard of this, or experienced it themselves, any advice would be much appreciated. Thanks in advance....Derrick

[ctaylor738]

Didn't these engines have a emissions control feature that reduced fuel flow in 4th gear, controlled by a solenoid on the injection pump? If you have this "feature" try disconnecting it and see if it solves the problem.

Thanks Chuck....I will give that a try.

[Aaron]

There is a decelleration solenoid on the back of some pumps. That is the one that is sometimes disconnected. I don't think it would help the problem you are having though. I'd check the throttle linkage, pump mixture (full load) and just for measure, check operation of choke stat. You might need to add shims.