Transfer height/ piston wash

[spencerdiesel]

Hi all, just put a new OEM Husqvarna cyl and piston on my new to me 346xp. I bought the saw with an AM top end and chicom carb.
As I am dabbling in port timing and such I put the wheel on and checked stock port times on the new OEM jug for curiosity.
I first checked transfers with a light shining through exhaust port and looking into the plug hole.
I then checked transfers using the right method of pushing the ring into the bore with the piston until it was at the top of the transfers. The discrepancy is huge between methods, but just based on what most 346s run for trans height, I just can’t believe the numbers I got from checking with the ring?
The “looking through the plug hole method got numbers very much what I would have expected for a stock 346.
Both methods gave repeatable and consistent results. Pay no mind to the blue writing, that was the AM top end.
Using the ring method I repeatedly got 133-134 degrees for transfers???

Also after a good hard break in I noticed the was more wash from the flywheel side trans than the clutch side. Is that due to the fly side trans opening a degree or two sooner and “venting” the majority of pressurized mix? Of course this is just a point of curiosity for me and I know it’s inconsequential. Thanks y’all!

 

[drf256]

I’ve never done a 346 myself, so I can only tell you my opinion based on theory and other saws. I have done a 357, which is in essence a larger 346.

The visual method for the ports varies widely vs the ring (proper) method. It’s clearly the only method for the intake port. The exhaust port gets close if one looks down the plug hole and opens the piston until light is seen, but that’s about the closest method I’ve gotten with that. Transfers need to be done with a ring, period. I’ve been off 10* visually with them myself.

Your blowdown question. 28-29* of BD on a factory quad port saw is about right. You have a restricted exhaust from a tighter (than we like) muffler. Under 20* from the factory in a Quad is uncommon. In a dual port I’ve seen it. In a Stihl 046, I’ve seen 14* from the factory. Some quads open earlier than one would expect. The Stihl 461 is a quad with long transfer tunnels. The theory is that they intentionally back stuff the uppers as a “poor man’s strato”. The first volume of the loop is exhaust.

Husky jugs have been known to open the PTO transfers a bit earlier than the fly side. Multiple theories exist, but when there is a difference in factory height, it’s generally the PTO that opens earlier.

The fly side wash generally always looks better because of “coking” on the top of the piston. The PTO side of a saw runs hotter and the piston accumulates more carbon on the crown. It makes the PTO side appear like it’s being washed less. Just how it generally goes.

 

[spencerdiesel]

Thanks for the in depth response drf256! I apologize for the delay from my end. How did your 357 end up and what did you think of the saw overall? I have an early (not early enough to be the narrow rod) 357 and I love it!
Interesting info on the wash of the quad port vs dual port. That clears up the uneven wash as well on my saw! Really pleased so far with how this 346 runs stock. My first and only saw I’ve ported so far (husq 353) runs neck and neck with the stock 346. Not sure how bad that is lol. But it’s 50% faster than it was stock before porting.