Base Gasket Delete Porting

[Thesandman]

Ok I did a search on what happens when squish is reduced by BGD or cylinder base cut. I know it's here somewhere but I can't find it so let's discuss it now. I'm new to this so bear with me. By lowering the cylinder on the piston(or raising piston in cylinder) the compression and power stroke duration increases, intake duration increases, trans and ex duration decreases. In my poulan the piston crown stops at ex port floor(and I assume trans floor too) so if cylinder is lowered piston now obstructs lower ex port opening and probably trans too. Not sure what piston does to intake port. as far as occlusion. Would we want to open ports to stock settings? Taper piston crown and skirt to reduce obstruction? Thanks

 

[Redfin]

You barely changed much deleting. Pull the numbers to make a plan forward.

What saw?

 

[srcarr52]

Pulling a base gasket (0.010-0.020" thick) on most saws is less than 1-2deg opening on port timing (2-4 deg duration).

 

[Thesandman]

I'm talking saws generally but also cutting .02 to .03 off bases.

 

[srcarr52]

I'm talking saws generally but also cutting .02 to .03 off bases.

Every saw is different. The stroke and rod length play a big role. Also the change in crank angle due to a change in port height increases the further you get away from the center of the stroke, it's not a linear relationship.