Hi folks, I rebuilt my 300 (1982) a few weeks ago and have a problem, it got all new everything. (Head cracked, had beucoup miles decided to go all the way.) The only internal engine moving parts that are original is the crank ( - 10 regrind) and the rods. The intake and exhaust manifolds are original, though the pollution control gear sorta fell off a long time ago.

The idle sucks badly, literally. Idle vacuum is only 14 -15 inches (should be 18-21), no large variations, and I can’t find a leak anywhere. Did the propane test, with all vacuum lines off and plugged.

I’ve swapped carbs, just in case, off idle performance is excellent.

One question that came up is valve adjustment, according to the book I have (chilton, CD Rom, Commercial version) "Tighten nut until all play is removed, then one full turn." Engine off and cold. I’ve had some disagreement about that adjustment procedure from others.

This is not the first engine I’ve rebuilt by far. I was a line mechanic for more than 9 years. This one’s got me stumped. And I need this thing right for work, I pull some heavy boats on occasion.

Any and all suggesstions will be greatly appreciated.