Chainsaw Repair

Quote from: 1manband on October 20, 2015, 10:14:43 pm

......when i last looked into changing degrees into mm's or inches (a year or two ago)......a few of the programs that are available on the web, do not account for 'pin height' (called compression height these days).....and may lead you to some blunders or maybe they are just calc mistakes?  i don't know how they came up with their calcs.......be aware.
knowing where the crown and bottom of skirt position is, the important thing.

They are probably calculating the compression height from a given squish clearance, stroke and rod length.

the first program i made solves it the way you are describing, the degrees change when you pick a your initial and/or final squish clearance that you will be using.

the 'free' programs that i looked at, at that time.....did not have a squish clearance option.  believe they must have worked from TDC=0 only?

whatever the reason, they were off.  at TDC and BDC, piston movement is minuscule, but if it's off there.....than that error widens as CA degrees get larger.

if anyone wants, am willing to share the formula.....and the more difficult aspect of making the formula work with their own program. nothing to hide.

the way i see things going.......in about 5-10 years, the motors will either be strato w/cats or DI.  this stuff is going away fast, and the more people that can keep it going, the better.