My D100 loves the winter - It runs Perfect , while it's not full blown winter yet, we get temps in the 20's & 30's, had some in the teens . All my summer symptoms are gone. To keep it running this way when spring arrives is my goal
about 75 degrees is when the fun starts 90's haha .
Is it the lean burn system ?
Vapor lock ?
I believe as a base consideration just to create a baseline this truck needs the LBurn out.
Plugs are clean, oil burn Not really but gotta change valve cover gasket. I do lose some oil.
Using Mobil One 10W40 synthetic.
What great motor's the slants are.

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Rediscovering what has been forgotten by many
the slant 6

It could very well be the lean burn system. I would replace that first thing. If you are not in a position to replace the lean burn system, then you should at least get the factory service manual for your particular truck and go through the troubleshooting and maintenance section for the lean-burn system and make sure all components are present and properly hooked up, especially all the vacuum hoses.

My 86 d150 had the ESA computer on it when I got it. Non feedback 1945 carb and no 02 sensor. I switched it over to standard electronic ignition and never looked back. I played around with different vacuum advance pods and springs. I was able to get good power using a Holley 1945 carb. I have just switched over to a Holley 1920 carb and the driveability is pretty good. I just think the 1920 carb is easy to work on. The lean burn system just has too many things that can possibly go wrong with it. I never did a HEI conversion, I just can't bring myself to put GM parts on a Dodge I would switch it over whenever you can.

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