372 and 460 both with pop ups needing help please

[ELECT6845]

372 with a .030 pop up runs great but the 460 is horrible so please help me out. The numbers on the Stihl are .030 on the squish with the exhaust at 101, transfer at 120 and intake at 73.
The 372 is .024 squish with 104 exhaust, 127 transfer, and 70 on the intake. So why is the 372 a decent runner and the Stihl sucks? Are my numbers wrong? Did I mess something up? Any help would be greatly appreciated just trying to learn from my mistakes. Guess we all gotta start somewhere.

 

[mdavlee]

Give the 460 some more intake to feed it. Other than that the numbers are pretty good. The other thing is port shapes.

 

[ELECT6845]

Give the 460 some more intake to feed it. Other than that the numbers are pretty good. The other thing is port shapes.

So move the port down alittle? Say to 70?

 

[mdavlee]

Lowering the intake to say 78 or so will give you 10° more duration total. It will be able to cram more mix into the bottom end before it closes off.

 

[ELECT6845]

Ok I'll give that a try. Thanks

 

[WHSH]

I am a working saw porter not a race saw guy and this is what I have done on the 460 and the 372 and they are very good 24" bar saws.
Shoot for .025 squish on both
460 195-200 psi, I have done a 210psi and it still running and wicked strong.
372 185-190psi with weaker crank, use no base gasket to preserve the already thin base casting, I have broken bases with too thin a base and 230psi. Learners mistake
80 BDTC for both intakes
100 ex for 460
99 ex 372
BD 20 deg for both
120 Tr for 240
119 tr fo 372
On either saw don't ream out the transfers, you want to keep the speed of the charge up.
65% of bore on ex and intake width
Squareish the bottom of the intake port, More time area
knife the 372xp transfer divider
Taper the lowers to the base on the 460
Clean Polish ex, and lower trans on both
on the 372xp shorten cyclinder sleeve/bore so it does not hit the case or crank due to droping the cyclinder down not gasket or base cut.
concider the chamfer "the port opening" and make it clean, smooth and a small radius.
you get most of your gains from the compression bump, timing and better flow. The port width is secondary to these three but is important.


All your numbers sound like you have slow rpm saw with big compression.