packing a crank

[barkies]

Hey guys Ive been listening to a couple of local guys talking about packing crankcases any one want to give a rundown of what it is and how hard it is on a saw.

 

[Lakeside53]

What was the context?

 

[Mr.]

He's asking about "stuffing" a crankcase for improved performance.

The gains would be minimal on a stock saw. Alot of cases are too tight as it is.

These guys are old timers. Don't correct them because they probably know something else worth while. Age doesn't make you an old timer, it's the age of the idea.

Fred

 

[ozflea]

Modern day Pipes take away the need to stuff the crankcase, stuffers were used before the advent of the pipes. Especially on the early kart engines.

Mc Bob.

 

[PES+]

Stuffing of cases came from old road racing and scrambles 2 stroke bike motors. A relatively long stoke combined with relatively small tranfer port areas required tightening of the volume of the case to create a higher pressure to move more charge into the cylinder. For some odd reason chainsaw designers still use stuffing techniques that have been known for years to not be applicable to current stroke and transfer designs but are throw backs to the 50s and 60s....and I am called old school:biggrinbounce2:

 

[timberwolf]

If your into racing, I think most saws could use more crank volume if anything, esp modified.

Threre are a few saws that I think might be a little big, in case volume, look at ones line the 365/372, case volume seems about right for the 372, but the afterthough 365 may be a little bigger than ideal. Same goes for the stihl 290 jug on the same lower end as the 390.

 

[PES+]

If you increase the transfer area ABSOLUTELY......to be fair in my thoughts regarding the factories I am sure their CC volumes are a struggle with the noise and or emmisions demands of using small can mufflers. I am just getting back to muffler tricks that I shelved years ago