Ironworker
Super OPE Member
- Local time
- 4:42 AM
- User ID
- 430
- Joined
- Jan 7, 2016
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- 261
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- Location
- Orange County NY
OK, what are good numbers for a 390.
36 24 36
I never really got the whole short girl thing. Give me one that's 5'10" and legs a mile long.
OK, what are good numbers for a 390.
I've done them with .030-050" from squish. They all ran close but one had higher compression. Depends on the bar length as well. If you want to run short bars you wouldn't need as much out of the chamber to get the exhaust lower. I've not seen any gains from lowering the intake to 85 on any saw. Epoxy it back up to 78 is better to me.A serious question needs a proper answer.......
I was taking .040 out of the squish band to get the exhaust down as far as possible.....had a few starter pawl failures out of some loggers in MI. So.......I dialed it back to .030 out of the squish.
I set the clearance to .020, and widen the intake and exhaust a little. I set the uppers to 120, and don't widen them at all.
On the ignition timing I advance it about 1/4" at the outside edge of the flywheel by filing the key. It's cast in on the 390, but it works that same way......
Lots of muffler opening helps that saw too.
I've done them with .030-050" from squish. They all ran close but one had higher compression. Depends on the bar length as well. If you want to run short bars you wouldn't need as much out of the chamber to get the exhaust lower. I've not seen any gains from lowering the exhaust to 85 on any saw. Epoxy it back up to 78 is better to me.
Yep. I should have proofread it twice.I think you meant intake........and I agree.
I'd rather leave to exhaust a little higher, then to take more out and end up with the intake real long.
yes,
it is when the port opens thats why there is that convention.
or you can assume symmetry and just list the duration.
I'm trying to use duration now but I still gotta figure it in my head everytime but I'm getting there. Makes more sense to talk duration instead of degrees ftdc.Thanks David. I'm more used to measuring duration so as to avoid having to deal with TDC.