Shoot your close nuff to come run it lol. Tuesday at the soonest for any cutting vids. Gf has a 3 day weekend. So family time till then.
Quads seem to be more efficient at filling the the chamber. You can read alot about "back stuffing" the transfers with a shorter blow down. This saw may be different, but I think you have a great idea trying some more on the next one. Its nothing to pull the jug and rasie them a tad if you dont like it. Nice work Joe.
Looking at it a bit more, and with what little time I have on it I can see 21-23 bd about spot on. Jut widen the transfers a bit, instead of raising them. Think the next one may get a pair of staggered fingers... I like to keep bd on the low side, as u feel it keeps the mid range while adding a bit to the top half. I haven't tried to make a "fast" saw yet, just been aiming for strong work saws. But willing to try some new things...
Husqvarna 268 piston is on the right of all pics. And the newest echo 680 piston left. 268 piston skirt is 1.39 wide. Just at 70% of the bore. But the exhaust outlet flange would be non existent at 70%wide. Plenty of skirt to avoid free port Looks like minimun .020-30 would have to come out of the band to set squish, before even cutting the base. Have to find a scale but definitely feels lighter, and a lot more flow potential.
Are you having to cut the squish band that much because of the 268 piston? Definitely looks lighter from the pictures.
Yeh, the band will definitely have to be cut. Not sure exactly how much. But I'm sure it will be in the 20-40 tho range. Nice thing about it is a flat band, vs tapered using the echo poston
Did you say the xfers in this were closer to a 90° angle and not rounded? Wonder if the flat top piston will effect that?
The transfers had /have a flat roof. 90* to the bore. No real benifit I can see to use a domed piston. Other than being able to run looser tolerance at factory and keep compression up. But since I will be taking so much out of the band to fit the piston compression won't be an issue.
Plenty of material in the chamber to take out. I didn't touch the band here. Just took it off the base to set squish where I wanted it. On this saw it would be .060 from stock to touching the chamber. .025 off the base, .015 gasket and .020 ish squish. It appears the 268 piston will take all that clearance and need .020-30 cut out of the band to set squish proper. Awol said he did one with a 268 piston pushing 245 psi.. with the taller piston the jug won't likely need to be cut at all.
32" full comp. that hickory is a little more rotten than I thought, but it will work well for comparisons.
