372xpw build and port thread

[Yotaismygame]

Local friend of mine hooked me up with this original xpw. The top end was toasted so I decided to rebuild it and of course port it. Can’t not port it

Apparently I don’t have a picture of when I first got it but it looked like it had been sitting for a while.

First things first I measured port timing and squish with a base gasket. EX: 104.5 TR: 126.5 IN: 73. Transfer height minus the exhaust height will give your blow down. So here we have 126.5-104.5= 22.5 degrees of blown down. Squish with a base gasket was .032”.

I decided to take off .040” from the squish band

And then .052” off the base to get squish at .020” with a gasket.

Machine work done

After that I checked squish one last time and then tore her down

 

[Yotaismygame]

Then I ordered parts and got to work on another saw.

This saw received lots of new oem parts.

complete top end
Skf bearings
Seals & gaskets
Fuel line
Fuel filter
HD air filter
Pull cord
Spark plug
Impulse line
Few new decals

 

[Yotaismygame]

Then onto the porting

I always start with the intake. Taking .040 off the band put the intake at 78 degrees. I did a little shaping and ground it to 80. Finished it off with a 80 grit finish

I then moved to the exhaust port. Always lots of grinding here. Finished the exhaust off with 500 grit. I also ground a small step in the floor. Height of the exhaust is 100 degrees

Last but certainly not least is the transfers. They got slightly stretched towards the intake. The height here is 119. So 119-100 = 19 degrees of blow down.

 

[Yotaismygame]

Actually the lower transfers was last...

I didnt take a ton of material off here. I wanted to build a saw with strong case compression. So I took the wall down by about 90% and smoothed some things out. I figured with the amount of material that came off the uppers and the wall coming down that would be enough.


The muffler got some work too. Spark screen still intact. I generally like adding pipes but decided to do something different and more low profile.

 

[Yotaismygame]

And bingo she’s done

 

[Yotaismygame]

And the evidence. Cuts great. Very strong case compression. I could really lean on it. Compression ended up at 175psi. I suspect it will gain another 10-15psi once the ring seats.

This saw is for sale. PM if you’re interested. #getjuiced

 

[old guy]

Looks & sounds strong, I will borrow some of your numbers and start a new cyl. to replace the one I raised the exhaust so high on with a popup piston.

 

[Yotaismygame]

I also made some custom tools. Like seal and bearing punches. I enjoy spending time on the lathe. For both bearing sizes 6202 & 6203

 

[Yotaismygame]

Looks & sounds strong, I will borrow some of your numbers and start a new cyl. to replace the one I raised the exhaust so high on with a popup piston.

I forget what the exhaust was at on your cyl but if you haven’t machined on it you could still use it. Get a new piston and have the squish band and base cut. It’ll bring the exhaust down probably to where you need it

 

[buttercup]

Then onto the porting

I always start with the intake. Taking .040 off the band put the intake at 78 degrees. I did a little shaping and ground it to 80. Finished it off with a 80 grit finish
View attachment 765290View attachment 765301
I then moved to the exhaust port. Always lots of grinding here. Finished the exhaust off with 500 grit. I also ground a small step in the floor. Height of the exhaust is 100 degrees
View attachment 765294 View attachment 765292 View attachment 765291 View attachment 765293
Last but certainly not least is the transfers. They got slightly stretched towards the intake. The height here is 119. So 119-100 = 19 degrees of blow down.
View attachment 765299

Nice work!

Why don't you round off the edges on the intake flange where it meets the rubber hose to the carb?

 

[Yotaismygame]

Nice work!

Why don't you round off the edges on the intake flange where it meets the rubber hose to the carb?

I flared it out pretty good. Opening is bigger than the intake boot itself

 

[old guy]

I forget what the exhaust was at on your cyl but if you haven’t machined on it you could still use it. Get a new piston and have the squish band and base cut. It’ll bring the exhaust down probably to where you need it

That one was at 95°, it's not that bad, I just want to do something else.
I've got a whole nother saw I can do plus 2 new oem p&c's.

 

[buttercup]

I flared it out pretty good. Opening is bigger than the intake boot itself
View attachment 765370

Ok, thanks. It's interesting to see the progress and what you actually do to it.

 

[NCPT]

Nice work as always. PM sent....

 

[Yotaismygame]

https://www.arboristsite.com/community/threads/husqvarna-372xpw-originial-rebuilt-ported.336224/

Officially for sale.

Get his piece of history. I've had quite a few saws come and go from my garage but this is the first XPW.

 

[lostone]

I have been thinking of using a 288 screen and deflector on my 372 build but wasn't sure if I would have the clearance. Looks like it will, judging by your deflector.

 

[Yotaismygame]

I have been thinking of using a 288 screen and deflector on my 372 build but wasn't sure if I would have the clearance. Looks like it will, judging by your deflector.

I think it would fit. But personally I would put it on the side not the top. Make it a dual port.

 

[Yotaismygame]

Something like these.

 

[lostone]

I think it would fit. But personally I would put it on the side not the top. Make it a dual port.

I'm wanting to keep it on top as close to looking to original as I can. USFS here has one guy that even his own co-workers call RAMBO, Largest (fill in your own expletive you want here) you will ever meet. Simply because there is no doubt in my mind he knows the rules and has the book on 2012 MSE (multiposition small engine). If you haven't read it, there is some very interesting reading on spark arresters in there.

Basically if it's a post 1978 saw you cannot in anyway modify the muffler, even in shape or size from what was approved from manufacturer and testing. Pre 78 is touchy.

 

[Yotaismygame]

I'm wanting to keep it on top as close to looking to original as I can. USFS here has one guy that even his own co-workers call RAMBO, Largest (fill in your own expletive you want here) you will ever meet. Simply because there is no doubt in my mind he knows the rules and has the book on 2012 MSE (multiposition small engine). If you haven't read it, there is some very interesting reading on spark arresters in there.

Basically if it's a post 1978 saw you cannot in anyway modify the muffler, even in shape or size from what was approved from manufacturer and testing. Pre 78 is touchy.

Around here the fallers i've talked to about it will use any muffler they want except during the peak of fire season. If you want to keep it as stealthy as possible cut the stock deflector mostly off and fold it back. The stock opening can be opened about 3x as much. Then fold it back down and weld it back up. Or maybe braze it?