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Replace the oil with Rotella T 15-40 and run it for 10 hours or so and see if it gets better before you tear into it. I’ve been around a dozen or so that burn oil due to the rings being carboned up. The detergents in Rotella T clean it right up after awhileDug this out to fix, bought it at a yard sale last year for 60$, it runs but it smokes like a chimney. Anyone know a good place for piston/rings?View attachment 209411
Piston is pre-scuffed...Better for power...lol
Already broken in.
Maybe put the old rings on the new piston? Pre broken in. More rpms... more powa. Lol
I have some redline 10-30 that has a buttload of detergent in it. Thats a great idea thnx, these things are a pita to mess with.Replace the oil with Rotella T 15-40 and run it for 10 hours or so and see if it gets better before you tear into it. I’ve been around a dozen or so that burn oil due to the rings being carboned up. The detergents in Rotella T clean it right up after awhile
Look at the new oil after an hour. If it’s working, it’ll be blackI have some redline 10-30 that has a buttload of detergent in it. Thats a great idea thnx, these things are a pita to mess with.
the piston is has some skirt wear
Those #s should work well. I had a 460 Hemi with the same squish and Ex, Tr 127, In 75 - it ran so nice w/o any port work I left it as is and did not take it apart to do the port work I planned.
Pistons with skirt wear on the intake side S/B replaced (your first assessment was correct) as the intake may not seal properly and will degrade performance. For the money REPLACE it!!!
Good luck with your build.
They are higher rpm saws. Your cutting style might make you prefer the 036’s over the 361’s. The 036 tend to have more lean on low end grunt. A ported 361 with the 044 carb and an 046 oiler is a true one saw plan.Starting to think these 361s are your new favorite saw!!! I know you do one heck of a job on the 036/360s, would be interesting to compare them.
Any thoughts on that?
I know the 440 carb one you did looks very strong!
Started on this 390 that had 145 psi comp, there is some scuffing above the exhaust port and the piston is has some skirt wear, thinking it’s due for a piston, it’s only $30 more than ringsView attachment 209452View attachment 209453 View attachment 209454View attachment 209455
View attachment 209462
Thanks! Just measured it at .010 differents! The exhaust side is thinnerBrand New 390s seem to have that same spot on the piston below the exhaust port. They LL seem fine, I would measuree the thickness and compare it to the intake side, if it it's within .001 I would run it.