Thanks for the continued advice....
The car is a 1972 california emissions vehicle, which meant that it came with a charcoal cannister. Apart from that, I don't see any EGR equipment of any kind, and with the newer intake manifold that I installed (the edelbrock performer 318/360) there is no provision for that either. To rule out any further vacuum leaks, I unplugged the vacuum lines that had run to the charcoal cannister assembly also. (but the car ran rough before I did that - it doesn't seem to make any difference.)
I have set the idle down into the 750 rpm range also - it doesn't seem to make any difference. The car starts to stumble and surge in that range.
Ironically, my 1970 Dodge Dart, which just had its slant six 225 motor rebuilt, is acting EXACTLY the same! It is if the two cars caught something contagious between the two of them. Now both of them stumble and surge at idle. Putting the Dart into gear makes it just about die. And with that car I have rebuilt the simple 1-barrel carburator, installed a new alternator, battery, electronic distributor, an MSD ignition, and all new plugs/wires....timed it to just 5 degrees advance....it breaks my heart! Runs so badly. Incredible. And the slant sixes are usually bulletproof, smooth runners, even under the worst circumstances. Crazy.
I have tinkered with and tuned-up mopars for over 12 years now, and never had issues like this....so puzzling!
I admit it is possible that both cars have some amazing vacuum leaks somewhere....but they are eluding me. Have checked what I think to be the obvious places so far.
Soon to be taken to a more knowledgeable mechanic than myself, I fear!
I will keep you posted as this pair of mysteries unravels.
Thanks again guys.....I know this is a difficult one.
-Mike T. scratching head and pondering his pretty cars that don't run so pretty
The car is a 1972 california emissions vehicle, which meant that it came with a charcoal cannister. Apart from that, I don't see any EGR equipment of any kind, and with the newer intake manifold that I installed (the edelbrock performer 318/360) there is no provision for that either. To rule out any further vacuum leaks, I unplugged the vacuum lines that had run to the charcoal cannister assembly also. (but the car ran rough before I did that - it doesn't seem to make any difference.)
I have set the idle down into the 750 rpm range also - it doesn't seem to make any difference. The car starts to stumble and surge in that range.
Ironically, my 1970 Dodge Dart, which just had its slant six 225 motor rebuilt, is acting EXACTLY the same! It is if the two cars caught something contagious between the two of them. Now both of them stumble and surge at idle. Putting the Dart into gear makes it just about die. And with that car I have rebuilt the simple 1-barrel carburator, installed a new alternator, battery, electronic distributor, an MSD ignition, and all new plugs/wires....timed it to just 5 degrees advance....it breaks my heart! Runs so badly. Incredible. And the slant sixes are usually bulletproof, smooth runners, even under the worst circumstances. Crazy.
I have tinkered with and tuned-up mopars for over 12 years now, and never had issues like this....so puzzling!
I admit it is possible that both cars have some amazing vacuum leaks somewhere....but they are eluding me. Have checked what I think to be the obvious places so far.
Soon to be taken to a more knowledgeable mechanic than myself, I fear!
I will keep you posted as this pair of mysteries unravels.
Thanks again guys.....I know this is a difficult one.
-Mike T. scratching head and pondering his pretty cars that don't run so pretty