372 oe piston options

[Ronie]

I've put a non windowed 268 piston with a pop up in a couple of saws and I think they gave a little more torque over the stock piston.

 

[Kiwioilboiler]

I've put a non windowed 268 piston with a pop up in a couple of saws and I think they gave a little more torque over the stock piston.

Sweet. I've got 160psi at sea level with just 15 minutes unloaded running. What'd the 268 saws squeeze?

 

[Ronie]

Sweet. I've got 160psi at sea level with just 15 minutes unloaded running. What'd the 268 saws squeeze?

They where both around 190-200.

 

[Kiwioilboiler]

They where both around 190-200.

Whoa!!

 

[Ronie]

Whoa!!

Them numbers are right after they were put together, so they still had a light coating of oil in the cylinder.

 

[cuinrearview]

Why not find someone to knock a little off the base of the jug to set squish with whatever piston you want? Wouldn't neccesarily need a lathe to do that if a fella knew what's what with a mill. Of course the timing would need to be at least looked at after...

 

[Kiwioilboiler]

Why not find someone to knock a little off the base of the jug to set squish with whatever piston you want? Wouldn't neccesarily need a lathe to do that if a fella knew what's what with a mill. Of course the timing would need to be at least looked at after...

In a perfect world that'd be the ideal, but I don't have anyone I can rely on to do that work locally yet.
So in the meantime I'm all about chucking together good component choices lickety split and knowing that "I did it".

 

[Kiwioilboiler]

Them numbers are right after they were put together, so they still had a light coating of oil in the cylinder.

Never occurred to me to check at that stage of the build, felt sure it'd be sweet FA due to the rings not having any time to bed in. I'll try next saw for kicks.

 

[Ronie]

Just my opinion, If I had to pay someone to cut the pop up I wouldn't do it. You would end up with $75-$80 in the piston and I don't think it would be worth it.

 

[Ronie]

knowing that "I did it

There's a lot of satisfaction in doing something yourself rather than having someone do it for you. It might not have the speed and power of one done professionally but like you said, "I did it".

 

[Jedd]

Hi Adam. Shame I didn’t see this earlier. If you stihl wanted to try a 268 windowed piston, i have a farmertec one in the garage that has a small pop up you could try. Went well in the cylinder I was using but I have now trying a big bore with a pop up husky 180 piston as a bit of an experiment (my 372 is chinese and mostly used just for firewood and an excuse to tinker in the garage). The 180 piston has a larger pin to crown height so has a much bigger pop up. Not sure it helped much as it is one heavy piston. compression gains seem a bit lost to the piston weight a bit.
I just got the engineering lads at work to turn the pistons for me - not much that can't be achieved there if you turn up with a box of beer on a Friday arvo

 

[Kiwioilboiler]

Hi Adam. Shame I didn’t see this earlier. If you stihl wanted to try a 268 windowed piston, i have a farmertec one in the garage that has a small pop up you could try. Went well in the cylinder I was using but I have now trying a big bore with a pop up husky 180 piston as a bit of an experiment (my 372 is chinese and mostly used just for firewood and an excuse to tinker in the garage). The 180 piston has a larger pin to crown height so has a much bigger pop up. Not sure it helped much as it is one heavy piston. compression gains seem a bit lost to the piston weight a bit.
I just got the engineering lads at work to turn the pistons for me - not much that can't be achieved there if you turn up with a box of beer on a Friday arvo

No worries mate. It's unlikely to get any more tutu now it's together. Good saw it is.

Where you based?

 

[Jedd]

Christchurch. Just sing out if you change your mind

 

[Kiwioilboiler]

Christchurch. Just sing out if you change your mind

Ta. Appreciate it cuz.

 

[Kiwioilboiler]

@Jedd in a strange twist the 372 in question must have lived close to you at some stage. It has a Meads Mower and Chainsaws sticker on it anyway.

 

[Ronie]

Hi Adam. Shame I didn’t see this earlier. If you stihl wanted to try a 268 windowed piston, i have a farmertec one in the garage that has a small pop up you could try. Went well in the cylinder I was using but I have now trying a big bore with a pop up husky 180 piston as a bit of an experiment (my 372 is chinese and mostly used just for firewood and an excuse to tinker in the garage). The 180 piston has a larger pin to crown height so has a much bigger pop up. Not sure it helped much as it is one heavy piston. compression gains seem a bit lost to the piston weight a bit.
I just got the engineering lads at work to turn the pistons for me - not much that can't be achieved there if you turn up with a box of beer on a Friday arvo

Do you remember what the measurement was from the pin to top of the piston was for the 180 piston?

 

[Jedd]

Do you remember what the measurement was from the pin to top of the piston was for the 180 piston?

Not off hand sorry. Will have a search thua weekend to see if I wrote anything down. It seemed like a good idea at the time as i dont have a way to lathe the cylinder base although i could sand the squish band manually. the 180cd piston in addition to a higher pin to crown height had massively wide skirts that were also a little deeper than the 272 windowed piston. Working ok at the moment but not entirely sure of longevity. Main problem was I had to make up some little brass bushes to keep the wrist pin bearing centred in the rod - the gap in the middle of the piston bosses was much wider than the 372 item.

 

[Jedd]

 

[Jedd]

Couldn’t find any words but did find theses pics I took of some 52mm pistons. All joined by pins so can see crown height and skirt length relative to pin location. The 180-480cd piston, a windowed 272, generic am piston and The pop up piston from the hyway cylinder and piston kit. Looking at reminded me that I actually took some off the sides of the piston skirts of the CD to match the base of the transfers