Husqvarna 371 attempt

[Red97]

Well got the 350 under my belt, now to try something "pro grade"





Saw came from auction no known history. Started right up cut oiled good. 150 comp



Going to swap this out.. Though it would have been unlimited being a 99



Intake side of the piston (notice no locating pin)



Exhaust side, found the pin.... Really surprised it didn't catch.



I think the original piston lost the locating pin and someone swapped in a new one backwards. You can see a few contact marks in the squish



Checked the numbers with a gasket. over .032 squish
In, 74 Ex, 99 Tr, 121

Made all the goodies for the 50 mm jug today,


Alum is to cut the squish band, wood is to sand the band, and white plastic is to cut the base.





cut .035 from the base, going to set squish at .020-.022. Intake should end up round 78/79, going to set exhaust 100 transfers 120, saw is going to wear a 24" bar

Thoughts and opinions welcome

 

[Big_Wood]

that saw was originally unlimited. it's sporting a 390 coil unfortunetly

 

[Red97]

that saw was originally unlimited. it's sporting a 390 coil unfortunetly

It is going to get am unlimited when it is finished. I was curious where the 13k coil came from.

Thank you

 

[tree monkey]

looking good

 

[Red97]

looking good

Thank you,

I am thinking about smoothing/blending the lower transfers. Concentrate on shaping the upper transfers correctly and widening the intake and exhaust a bit.

Thinking "less is more" on this particular saw.

Only ran a 37x husky for a couple cuts, but it seems to be dialed in pretty close.

If I am way off in my thinking, I am open to suggestions.

 

[tree monkey]

your numbers look good to me

 

[tree monkey]

http://www.arboristsite.com/community/threads/tree-monkeys-2153-deluxe.271078/

study this

 

[Red97]

Squish set to .021


Exhaust set at 100




Still have a little bit of polishing to do.

Intake ended up at 78 taking .035 off.

 

[Onan18]

If you really want to wake it up remove the sections that shroud the lower transfers. Watch the Afleetcommand videos on YouTube, 372 Saw College Part Two Spike60 goes over this in detail.

Joe

 

[Red97]

If you really want to wake it up remove the sections that shroud the lower transfers. Watch the Afleetcommand videos on YouTube, 372 Saw College Part Two Spike60 goes over this in detail.

Joe

Thank you, I will look into that.

 

[Chainsaw Jim]

If you really want to wake it up remove the sections that shroud the lower transfers. Watch the Afleetcommand videos on YouTube, 372 Saw College Part Two Spike60 goes over this in detail.

Joe

You mean like this?

 

[Red97]

Polished the exhaust a bit more



Roughed in the lower transfers



You can see how much I dropped the flange. Didn't want to go too far, since I am widening/shaping the tunnels a bit.
My thought process is, the charge flows from the case up through the tunnels and out the ports. So I am trying to increase the velocity as the charge exits the transfer ports. Trying to gradually taper from large (at the base) to small (transfer exit). Trying to guide the charge the entire way through the transfers. Sounds good in theory, but much harder to achieve



Still have a bit of blending and smoothing left, but you get the idea.

 

[Red97]

I only raise the sides maybe 1/8". I've tried higher and didn't like the outcome. The piston got windows in it so that could have been the other cause to that.

I am still roughly 1/8" above the base. Did it make the saw very "peaky"?

When you say the "piston got windows" you mean like the 2xx saws?

I am all ears, I have a few ideas, but like hearing what has worked/not worked for others.

Thank you

 

[Frank Savage]

If I remember correctly, about 3 years back Mastermind had a thread running about 372 where he tested windowed piston and he was not much keen about the outcome.

 

[David Young]

Looking great Joe!

what are everyones thoughts on staggering the transfers vs. all at once?

 

[Red97]

Looking great Joe!

what are everyones thoughts on staggering the transfers vs. all at once?

In this jug

I could see it beneficial to open the exhaust side a degree or so earlier. To push the exhaust out and create a " wall" so when the intake transfer opens it doesn't escape out the exhaust.

I don't know, but just looking at the ports, the transfer toward the exhaust is larger, (opening at the base, and the tunnel). So in my mind that port will be a little lazy, it will have the volume, but not the velocity.

Then when the intake side transfer opens it would run in the clean charge from the other port that already pushed the remaining exhaust gasses out

I may be way off, but that is just my thought process...

 

[mdavlee]

You can open one before the other. I would think intake side would be better as to not trap burnt or semi burnt mix in the chamber.

 

[Red97]

You can open one before the other. I would think intake side would be better as to not trap burnt or semi burnt mix in the chamber.

Or this ^^^^

I want to come up with some kind of "smoke machine" flow bench to test these things.

I do not have near enough experience to say which way is better. At this point I am just sticking with mostly tried and trued methods.

Still trying to fine tune my hand piece skills, that rt angle is a tricky lil bugger

I do appreciate any and all feedback received, just trying to do the best I can with what I have to work with.

This will be the 3rd saw I have pulled the jug off to do some "port work" to, so If you happen to see something that looks out of place or odd feel free to mention it.

Thanks

 

[tree monkey]

I've done it both ways, open the primaries 3-4 degrees before the secondary's. the big ones

 

[Red97]

I've done it both ways, open the primaries 3-4 degrees before the secondary's. the big ones

Thank you,

You do that in a work saw? or more of a "play" saw?

So the primary's are the small ports, and the secondary's are the larger? Like a quadrajet carb?