359 port timing numbers

[jonsered 535]

Hi again everyone I know there are a lot of threads about port timing. This is my first one and want to get it right and am wondering what kind of numbers I should go with on a 359. I set the degree wheel up before I take anything apart so I can see the exhaust through the plug hole and have 76 1/2 which is 103 1/2 so I can have a start on it. Wondering what numbers I should port to and how much blow down I need. I just want to be able to get some woods porting numbers.
Hopefully I can get some knowledge here
Thanks

 

[Four Paws]

Port shape is more important than timing numbers.

Good luck on your first build. Some easy and safe numbers are as follows:

Ex 100-105
Xfr 120
Int 80

 

[jonsered 535]

Thanks for the reply four paws I just checked the squish without the gasket and got 0.026 on four sides of the piston so she should be good without the gasket there. Those numbers you gave me are good for the 359 are they.

 

[jonsered 535]

Gonna check the stock numbers there now that I have her taken apart and all cleaned up.
When I check intake number is it when the piston skirt just starts to open up on the bottom of the intake?

 

[huskihl]

Gonna check the stock numbers there now that I have her taken apart and all cleaned up.
When I check intake number is it when the piston skirt just starts to open up on the bottom of the intake?

Yes

 

[jonsered 535]

Just checked my numbers stock with no gasket and looking in with light in front of me when they just start to open and
Int 78.5
Ex 105
Xfr 122.5
If I'm doing my math right or reading the wheel right, the wheel shows on Ext 75 so I subtracted it from 180 and got 105 is that how I do it

 

[huskihl]

Yeah that should be right. Make sure you found TDC correctly. I go from when the exhaust closes to when it opens and TDC is exactly in the middle. It's pretty easy to miss 3 or 4 degrees of crank rotation at tdc if you're just looking for when the piston changes direction

 

[jonsered 535]

Yeah that should be right. Make sure you found TDC correctly. I go from when the exhaust closes to when it opens and TDC is exactly in the middle. It's pretty easy to miss 3 or 4 degrees of crank rotation at tdc if you're just looking for when the piston changes direction

I put a piston stop in and went both ways and put the wheel showing the same for both ways and when I took it out it seemed to be perfectly tdc on zero

 

[jonsered 535]

Question? Four paws said 80* was good but I am at 78.5 and I have no way of cutting the base of the cylinder to get it down the 1.5* (Wish I could my squish is at .026 with no gasket.)can I take it off the bottom of the intake or will I shag it something up?
Or is the 78.5* nothing to worry about
What will the gain be for the 1.5* that i'm missing.
My base gasket was .020 thick when I took it apart.

 

[huskihl]

I don't know that saw in particular, but in every other saw I've done, I've ground down the intake. But again, not familiar with that one

 

[jonsered 535]

I thought that maybe I could take it from the bottom of the intake but saw another thread where they cut it down at the base but no difference I guess other then my squish wont be as close as I would like to see it but at .026 I will be very safe.

 

[pioneerguy600]

Old school would be to sand the base down by gluing a sheet of 200 grit sandpaper to a sheet of thick glass, 5 strokes one direction, turn 90 degrees and do 5 strokes, turn again and repeat as often as it takes to remove the .012 or so needed. This is how we did it before getting into lathe work.

 

[jonsered 535]

Thanks pioneer I thought about that but are the gains worth it. Wil I see a big difference by doing it?
The saw worked good before I got it in my head in doing this, my goal is to have a reliable saw with a bit more power and speed for fire wood junking, I saw a lot of YouTube videos of how fast some were in the 359's I don't care if it's that fast as long as it's reliable and a bit faster then what she is now with a bit more torque, the biggest problem for me is knowing the timing numbers that will give it to me as I'm learning what the effect of the where to port to get the gains I'm looking for

 

[mdavlee]

I wouldn't worry about the 1.5° of intake timing. Square up the intake as is to gain more time/area.

 

[ELECT6845]

Thanks pioneer I thought about that but are the gains worth it. Wil I see a big difference by doing it?
The saw worked good before I got it in my head in doing this, my goal is to have a reliable saw with a bit more power and speed for fire wood junking, I saw a lot of YouTube videos of how fast some were in the 359's I don't care if it's that fast as long as it's reliable and a bit faster then what she is now with a bit more torque, the biggest problem for me is knowing the timing numbers that will give it to me as I'm learning what the effect of the where to port to get the gains I'm looking for

I would leave the intake at 78. It will give the saw a little more torque. You can also make the floor of the intake flat and square off the corners.

 

[jonsered 535]

I would leave the intake at 78. It will give the saw a little more torque. You can also make the floor of the intake flat and square off the corners.

Torque is good for what I want.
I have 105 on my exhaust now what effect will it have if I move it to 102 or 103

 

[sunfish]

I built a 359 for my brother and it is impressive. I just widened, squared up the ports, opened up the muffler & deleted base gasket. Didn't change any port timing.

 

[ELECT6845]

Torque is good for what I want.
I have 105 on my exhaust now what effect will it have if I move it to 102 or 103

Move it to 101 or 100 both work good. Don't forget to put a bevel around the ports so you don't snag a ring.

 

[jonsered 535]

I built a 359 for my brother and it is impressive. I just widened, squared up the ports, opened up the muffler & deleted base gasket. Didn't change any port timing.

How much did you widen them a 1/16 or so on each side??

 

[jonsered 535]

Move it to 101 or 100 both work good. Don't forget to put a bevel around the ports so you don't snag a ring.

I like it and am wondering what it changes like speed torque etc. what effect or how what changing it does.