This is a later model 61 that actually has a tilly with a 20 mm bore. I do not know if it came from factory that way, but the cover is made for the carb, but a 272 filter will not fit under the cover. Everything else is the same, a direct bolt on.
Installed piston and jug, squish is .027 with no gasket. Set up degree wheel and specs are as follows:
exh opens 104 atdc
dur 152
trans open 120 atdc
dur 146
int opens 107 abdc
dur 146
blow down 16
How do these numbers look? This is just a work saw and for me a creative project. The used gasket that I measured is .020 thick, so I was going to cut .027 to get the squish at .020 with gasket. I realize specs will change, but haven't done this before and don't have it in my mind how this would affect the timing. Any help on that would be appreciated.
Then I was going to try some porting based on what I have read and seen on this site. And of course, a muffler mod. I will post some pics of my 3120 muffler too when I finish it (sawmill saw).
Another question, how much compression would be picked up if squish was changed from .075 to .020? That is what the saw was originally. Compression was lower than my other 61, which is an older model.
Any help or advice appreciated.
Larry
Installed piston and jug, squish is .027 with no gasket. Set up degree wheel and specs are as follows:
exh opens 104 atdc
dur 152
trans open 120 atdc
dur 146
int opens 107 abdc
dur 146
blow down 16
How do these numbers look? This is just a work saw and for me a creative project. The used gasket that I measured is .020 thick, so I was going to cut .027 to get the squish at .020 with gasket. I realize specs will change, but haven't done this before and don't have it in my mind how this would affect the timing. Any help on that would be appreciated.
Then I was going to try some porting based on what I have read and seen on this site. And of course, a muffler mod. I will post some pics of my 3120 muffler too when I finish it (sawmill saw).
Another question, how much compression would be picked up if squish was changed from .075 to .020? That is what the saw was originally. Compression was lower than my other 61, which is an older model.
Any help or advice appreciated.
Larry
