MikeB Saw Shop
ArboristSite Lurker
Starting my first attempt at porting. I have a few saws I'm willing to ruin so might as well get after it.
First on the bench is a Stihl 024. I bought a project saw and it came with a spare long block. The story is that the saw got run over shortly into it's life and was shelved. The P&C look excellent so ill build up the long block and transfer the rest of the bits over.
I've got a new WT-194 carb for it. Stock numbers, no base gasket are:
Intake Open: 68° BTDC. 136° duration.
Exhaust Open: 99° ATDC. 162° duration
Transfers Open 128/129. ATDC. ~29° Blowdown.
Squish winds up at .017"
I plan to open up intake duration a bit. Shoot for 147° and if I over shoot it, no big deal. Maybe even more? I've seen other builds that are well into the 150's. I'll take some off the port, and some from the piston skirt to keep the port size reasonable to promote intake air velocity.
Exhaust seems plenty high as it is. I'll look into widening the port, and definitely polish it to the best I can make it.
I'm not planning to adjust the upper transfers. It seems like a longer blowdown, but I guess I'm not 100% on if that's an issue or not.
Lower transfers will be widened and shaped.
Squish seems good. With a few thousandths of gasket maker at the base it should wind up around a pretty happy .020".
Happy to hear your advice and experiences on small saw porting.
First on the bench is a Stihl 024. I bought a project saw and it came with a spare long block. The story is that the saw got run over shortly into it's life and was shelved. The P&C look excellent so ill build up the long block and transfer the rest of the bits over.
I've got a new WT-194 carb for it. Stock numbers, no base gasket are:
Intake Open: 68° BTDC. 136° duration.
Exhaust Open: 99° ATDC. 162° duration
Transfers Open 128/129. ATDC. ~29° Blowdown.
Squish winds up at .017"
I plan to open up intake duration a bit. Shoot for 147° and if I over shoot it, no big deal. Maybe even more? I've seen other builds that are well into the 150's. I'll take some off the port, and some from the piston skirt to keep the port size reasonable to promote intake air velocity.
Exhaust seems plenty high as it is. I'll look into widening the port, and definitely polish it to the best I can make it.
I'm not planning to adjust the upper transfers. It seems like a longer blowdown, but I guess I'm not 100% on if that's an issue or not.
Lower transfers will be widened and shaped.
Squish seems good. With a few thousandths of gasket maker at the base it should wind up around a pretty happy .020".
Happy to hear your advice and experiences on small saw porting.
