MS362 toasted piston

[MAF143]

I finally got some time to get back on that saw. I got it together far enough to put the timing wheel on it.
numbers with no base gasket are:
squish .015" I'll open that up a few thousands before closing this saw up.
Exhaust opens at 100* ATDC
Exhaust Duration 160*
Intake Duration 142*
Blowdown 31*

Without having a lathe to lower the exhaust, I'm sticking with this and the flow enhancements along with base gasket delete, timing advance, and muffler mod.

I'll find out later when I dig into my 362 if the newer ones have the same numbers. I can't imagine they would be different. Any suggestions of where these numbers could go without a machine shop?

 

[MAF143]

Working on the squish now, I cut 7* advance into the flywheel key.

 

[huskyboy]

Working on the squish now, I cut 7* advance into the flywheel key.

Nice, what was the stock timing at?

 

[MAF143]

I don't know, this saw was blown up when I got it to fix for him. My 362C I had advanced 6* and has no bite on a hot start so I pushed his a bit more just to see if it bites.

 

[MAF143]

I've got the squish out to 18.5 thousands at the thinnest spot and I think I'm gonna button it up and run it.

Thoughts??? With sealant is this gonna be OK?

 

[huskyboy]

I've got the squish out to 18.5 thousands at the thinnest spot and I think I'm gonna button it up and run it.

Thoughts??? With sealant is this gonna be OK?

Yes

 

[MAF143]

going back together.

 

[MAF143]

Yes

Good call!!

sealed up and squish is:



Next up, vacuum and pressure checks.

 

[MAF143]

I've never done a pressure / vacuum test on a chainsaw before.

The vacuum holds steady for over a minute.

The pressure bleeds off from 4psi to zero in about a minute. Is this OK or does this need to be found and corrected so there is NO bleed down?

Sorry for all the rookie questions, but after all, I'm a rookie just trying learn and help a guy out.

 

[MAF143]

Nevermind. I can hear the clutch side seal leaking under pressure, but is OK on vacuum... aarrgghh!!!

Always something. Never smooth sailing at our house... LOL

 

[MAF143]

Easy fix. When I put that seal in, I simply pressed it in flush with the bearing rim that holds it. It looked normal with no torn up or wierd bumps so I pressed it another .030" or so in and all is holding pressure and vacuum now with no bleed down. Sorry to sound like such a dummie, but sometimes I just need to talk through new things and a smiling face with a patient ear is all it takes to work it out. The big picture stuff I usually have a handle on, but it's the little details and "tricks of the trade" stuff that I haven't seen before trip me up.

Thanks for being good listeners...



That would have been a booger of a problem to find if I had not followed the advice of doing a pressure / vacuum test prior to full assembly. The big brains here have saved me a ton of trouble. Thanks ALL...

I've still got a lot to learn but it's been fun so far...

 

[RI Chevy]

This saw running yet??? Lol

 

[MAF143]

Almost... LOL I hardly ever get any spare time to work on it. I got to work on it about 1/2 hour at a time this morning and afternoon for 3 or 4 times between running to town and other stuff going on. Wife's mad at me cuz the yard is about 12" deep... I can mow later... LOL My nephew just left and we fixed their youngest boy's car so he can leave for college. I have to run into town and pick up my torches from his uncles place on the other side of the family cuz they're leaving for Vegas for a week and I'll need those for sure while they're gone if I leave them there... You know how that works...

Not enough hours in the day...

 

[RI Chevy]

I hear you.

 

[MAF143]

OK, I decided to spend this evening on this saw after we fixed Kyler's car.

IT'S ALIVE!!! sounds good so far, I'll heat cycle it a few times then put it on a break in run for a tank or 3.

 

[RI Chevy]

Nice job.

 

[MAF143]

Ran a tank of fuel thru it today with a couple more heat cycles and some light trim work and cut some 10" poplar cookies that took 5 to 6 second bursts to blast through It's almost as fast as my 2 year old 362C but it needs a few more tanks of break in and some time to fully come back to life. It sounds nice and crisp.

I did notice that it is heavier than my newer saw, by a good bit. I don't have good scales to weigh them on, but it's at least a pound or more. Mine's wearing my 25" light bar and his has my 18" bar on it for now to compare "feel". Even the neighbor commented on how much heavier the older saw was when he picked it up to look at it. It surprised me that there was that much difference especially with the much smaller B&C on it. I wanted comperable chains on them when comparing them. Both my chains are square ground and the chain on his bar (that needs dressed and deburred) was pretty dull and I didn't feel like messing with it. He asked me if I would show him how to square file and convert it, but I'm waiting to do that when he gets here to pick it up later in the week.

 

[MAF143]

He picked up his saw. I haven't heard if he has run it yet.

While breaking it in I did compare it to my 362C that is only 2 years old. His older saw doesn't hold the rpms up in the cut as well as mine and it has been bugging me why there would be a difference. Both saws have the same muffler mod, ignition timing advance, and of course his has the xfer port bottoms opened up, base gasket delete, and the exhaust port opened up just a tad. Mine is the M-tronic carb while his is the standard carb. While I'm not a wizard at carb tuning, I've never had any problems doing it either.

I was worried that maybe I had taken the roof of his exhaust port up while cleaning off the piston smear that got embedded at the top of the port. I had been very careful not to take any off there.

SOOO I took the muffler off mine this evening and put the timing wheel on it just to see where the exhaust on it is stock with the base gasket still in it. Mine came up with 101 opening and closing for a 158* duration while his was at 160* duration without the base gasket. I must have touched it more than I thought, but the chamfer had to be cleaned up in there.

Anyhow, I'm hoping his will wake up a little more after a few more tanks of mix.

I didn't check the compression on his since there wasn't much I could do about it anyway and it got new rings, but I'll have him bring it over after he's run it some and check it then and compare it with mine. I'm just curious to see where that rescued cylinder is compared to mine.

His saw is no dawg by any means but doesn't pull quite as hard in large wood as mine does.