372xp

[SawGarage]

From what I've read smaller case compression gives more peaky of a saw.

hmm....course, we're taking away when unshrouding the lower x-fers, and windowing the piston..

time to do some math, perhaps..

or just port it and run it.

that thing is a BEAR... I could only imagine square chisel!!

 

[parrisw]

hmm....course, we're taking away when unshrouding the lower x-fers, and windowing the piston..

time to do some math, perhaps..

or just port it and run it.

that thing is a BEAR... I could only imagine square chisel!!

LOL, ya, square would not work in that wood.

 

[dk27]

Is that all you did to the saw

Sorry was not clear at all.
This was just the last mod
Ported B.B.
case matched
cylinder raised
163*on exaust
161*on intake
I believe 120* transfers
Don't recall blow down of the top of my head
.023 squish
no gasket
175ish for comp

 

[SawGarage]

Will,

do ya have a compression #? what have you been seeing stock (or do they never come to you that way?? )

J

 

[parrisw]

Will,

do ya have a compression #? what have you been seeing stock (or do they never come to you that way?? )

J

Umm, I checked this saw at 160 with no only a minute of runtime. Stock probably 150.

 

[parrisw]

Sorry was not clear at all.
This was just the last mod
Ported B.B.
case matched
cylinder raised
163*on exaust
161*on intake
I believe 120* transfers
Don't recall blow down of the top of my head
.023 squish
no gasket
175ish for comp

Sounds good.

 

[SawGarage]

Umm, I checked this saw at 160 with no only a minute of runtime. Stock probably 150.

Will,

That's all? with the pop-up? huh... my stock 350 that has a BAD score in the cyl pulls 160... (PRIOR to break in...)

did you only pull a couple times? :dunno:

I just would think that the comp would be higher with the pop up...

hmm...


Not pushin' your buttons, just curious.

J

 

[tlandrum]

jay the 372 saws are not very high compression saws. they usually dont have but around 140 when new

 

[parrisw]

Will,

That's all? with the pop-up? huh... my stock 350 that has a BAD score in the cyl pulls 160... (PRIOR to break in...)

did you only pull a couple times? :dunno:

I just would think that the comp would be higher with the pop up...

hmm...


Not pushin' your buttons, just curious.

J

Well some testers are not perfectly accurate. I thought it would be higher too. I'll check again after a few more tanks and see what its at.

 

[SawGarage]

jay the 372 saws are not very high compression saws. they usually dont have but around 140 when new

Huh... my 371 pulled 160psi...

Well some testers are not perfectly accurate. I thought it would be higher too. I'll check again after a few more tanks and see what its at.

I agree with you. I double check mine on the compressor once in a while..



regardless... STRONG cutters!!

J

 

[parrisw]

Huh... my 371 pulled 160psi...



I agree with you. I double check mine on the compressor once in a while..



regardless... STRONG cutters!!

J

Yep, I've had this gauge not work once, it leaked and wouldn't build pressure, maybe its doing it again.

 

[2stroked2smoke]

My 372 only has about 165 comp with a .025 pop-up .024 squish. I think the 372 has a fairly big combustion chamber. Doesn't seem to affect the torque of the saw that much though.

 

[SawGarage]

My 372 only has about 165 comp with a .025 pop-up .024 squish. I think the 372 has a fairly big combustion chamber. Doesn't seem to affect the torque of the saw that much though.

sheesh... we could run mexican unleaded in these saws!! 83/85 octane should be sufficient...

people don't realize high octane actually makes LESS power... unless you NEED it to prevent pre-ignition...

J

 

[komatsuvarna]

people don't realize high octane actually makes LESS power... unless you NEED it to prevent pre-ignition...

J

Yep, thats right. My 372 pulled 140 when brand new. 150 after about 15-20 tanks of fuel. 160 after the porting with the base gasket removed.

 

[rch416]

I'm new to engine building so I'm curious what are you guys talking about with pop-up?. Also what's the benefit of putting windows in the piston?.

 

[SawTroll]

I'm new to engine building so I'm curious what are you guys talking about with pop-up?. Also what's the benefit of putting windows in the piston?.

It is best if you forget both expressions, if you are new to working on saws....

 

[parrisw]

I'm new to engine building so I'm curious what are you guys talking about with pop-up?. Also what's the benefit of putting windows in the piston?.

Pop up is the piston, gives more compression. Window's in the piston allow's more flow through to the transfers.