Been awhile since I posted. I finally made a little progress on my 72 D100 slant. I discovered the carb was puking out the accelerator pump (Holley 1920). I attempted a rebuild but one of the metering block screws broke off and when I tried to drill to extract the bit slipped and I egg-shaped the hole.

I wanted a solution I could bolt in without any modifications for now so I just bit the bullet and ordered a reman 1920 from Rock Auto. Out of the box and unadjusted I get a good idle. But it still shakes badly when revved. I did cap, rotor and wires today and that didn't help. When I first got the truck I pulled plugs to spray lubricant in the cylinders and they looked OK to me then. Guess I'll replace them next.

I also rebuilt the cooling system today with a new radiator so I can run it longer than a few minutes at a time.

Video of idle: https://youtu.be/Jd3PmmA09GE

Video revving showing the shake: https://youtu.be/9YA_StdQxGs

Need to shift my focus back to the brakes for now. Moving it around without brakes is...interesting.

Sounds good. Have you adjusted the valve lash yet or recently?

Best,
Lou

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Home of Slant6-powered fun machines since 1988

New update. I determined my existing coil was bad. So I replaced it and went ahead and added new plugs, points and condenser to the wires, cap and rotor I'd already done. What a night & day difference in how it runs. Unfortunately I have a leaky water pump and possibly a stuck thermostat (lower hose never gets warm).

Also decided to Google the block casting number of 2806830-2. Best I can tell it would probably be from 1971 which tracks with the 11/71 build date of the truck. Would this be a solid lifter engine?

Video of the post ignition rebuild idle: https://youtu.be/EsEC2aHTMYE

When the thermostat opens the upper hose gets noticeably warm. I would check the upper hose.

The cooled water is drawn back into the block in the lower hose.

You should have solid lifters. Pull the oil cap and peek in the valve cover. You should see adjuster screws on the rocker arms.

Greg

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http://www.youtube.com/hyperpack