Sooo close to smooth running...

That mag swap (a rebuilt from Mark's Magnetos) was definitely the biggest improvement [in fact, even started on the first crank tonight, but I did have it running for a bit a half hour earlier] with that 22-36 running rough.

However, it still gets a slight miss [which of course, ignites in the manifold], more likely when warm, but I won't say only warm. Doesn't seem to matter anywhere in the RPM range, but sometimes more or less throttle does seem to get it on track for a bit.

I did isolate it to #3 once [went completely dead, plug good and wet], so I'm thinking a sticky valve(s) rather than carb, but suppose it's possible for a cylinder to flood out and the rest run fine. The head had 3new valves, and 8 new guides.

At 1100RPM - except for the miss - it's pretty happy at 20 advance [probably get to 25 degrees if I take the slop out of the linkage - I'm on, or barely after, TDC with the impulse], but, like throttle, spark advance makes a temporary difference if at all.

10 to 15 [even at 20 it doesn't backfire from early spark] advance at idle around 400. I did get it set closer to a slow idle, but I'm somehow convinced [I'd be equally happy to be wrong or right on that :? ] the R carburator's idle setup just doesn't like the Heisler governor (I can get it down to 300 by hand, mimicing the orginal throttle linkage) unless you don't mind the first half of the throttle range being dead; regardless that's not really an issue. Like full RPMs it sometimes just wants to miss here and there.

Don't know why this thing wants to perplex me so much; it sounds so healthy otherwise.

Sticky valves would be my guess. Keep messing with it.

Spiffy. Add a cup of Marvel mystery oil to a tank of gas. Does wonders Luck Bernie Steffen

It needs a good hard pulling

james

Thanks guys! Did you guys send your ideas by telepathy before I caught up on this thread? Convinced (still possible the carb isn't perfect, but doubt off enough to cause missing) of sticky valves, I gave them a few squirts of MMO right on the valve stems, cranked it over a dozen times, and a few more squirts. Ran pretty smooth, and kept it up before acting up, longer than I recall yet [maybe not 5 minutes].

It has a date with a duck foot for a couple hours in it's very near future, if it laughs at that it can have 3-16s [if I get around to getting some different tires on it :roll: ] for a while. Just a couple more little things, like swapping out the rear end oil, first. But also I wanted it running smooth enough to not worry about a miss fouling out a cylinder.

I'm thinking it will get a cup of MMO in the tank to keep the valves cooperating, but [being paranoid] didn't want anything that could treat the cylinder walls before the rings seat- after that though, all the better!