Shake Shake Shake
I have the idle set just a tad high in the video here. It's about 800 rpm.
Why 800 in a 340?
I went to the Comp site, but trying to navigate thatchit just frustrated the dickens outta me.
I suspect a 270 H is a 270/270/110 sub 500lift cam with maybe as much as 224* at .050; I suspect.
If so;
You should be able to idle that down to 650 in gear, with the Transfer slot properly set. With a lil idle retard, I think it would go to 550.
I'm not saying that 800 is your problem, I'm asking why so high? As in; did you verify the TDC marks. It just sounds horribly timing advanced to me. And that would require a high idle so it doesn't stall.
on another note;
As I recall the factory forged pistons were something like 719 grams, compared to KB hypers at 543 or something. Seems to me if the crank was not balanced, the shake would be way worse, and it wouldn't come and go. A guy brought me a 360 once with an out of balance crank. It didn't act like yours. It shook continuously, and the faster it revved the worse it was. Had to take it apart and start over.
You know what I would do is; while it is idling,with the Vcan disabled, just give the Vcan a push back to the firewall to retard the timing;
If the engine speeds up before it slows down, it is over-advanced. Also; if it is horribly advanced, the exhaust will burn your eyes. Crank up the idle a half turn, then retard it some more;never mind about the timing lite;
just see if it speeds up first then slows down and smooths out.
If it does, then verify your timing marks with a piston stop..
