361 Shootout

[Anthony_Va.]

The gains are easy to see TW. Looks like you have got her purring.

I enjoyed the vids on the pop-up and base turning also. I've learned a load watching this thread so far. Appreciate it buddy!

 

[timberwolf]

Thanks guys, its fun.

This carb was just done by hand, likely the other two carbs will get a more involved work over.

 

[Zombiechopper]

Thanks guys, its fun.

This carb was just done by hand, likely the other two carbs will get a more involved work over.

If its not a trade secret kind of thing, could you describe how you work a carb over by hand? This is kind of a mystery to me. I'm picturing sandpaper on a dowel to open the diameter and smoothing the edges of the venturi?

 

[timberwolf]

I just use a small cutter and work the edge of the venturi down, measure here and there to keep it even, then smooth it out. 361 carbs are quite smooth to start, but some of the carbs are pretty rough in the venturri.

cleaning up the carb is one of the small things that on its own likely not even a measurable a change, but combine a few of these details and and it adds up.

 

[parrisw]

Thanks guys, its fun.

This carb was just done by hand, likely the other two carbs will get a more involved work over.

So, you didn't open up where the butterfly sits? Just the venturi?

 

[timberwolf]

Just the venturi. To open it up where the butterfly sits you would need to do it on lathe and use a larger butterfly. It can get tricky with internal passages and the LS orifices near the throttle plate.

 

[parrisw]

Just the venturi. To open it up where the butterfly sits you would need to do it on lathe and use a larger butterfly. It can get tricky with internal passages and the LS orifices near the throttle plate.

Ya, I've been wanting to try to bore a carb on my lathe. Was going to do my 371. I have a few throttle plates around that are slightly larger that would work.

 

[timberwolf]

The lathe work is the easy part, making that big of a change to the shape of the carb will throw the fuel curve way off and the carb will likely need some internal tweaking to get it running right esp for a work saw that needs to start, idle, accelerate, cut at different RPMs and return to idle without reving or stalling.

 

[Trigger-Time]

Bump

 

[MS390]

The lathe work is the easy part, making that big of a change to the shape of the carb will throw the fuel curve way off and the carb will likely need some internal tweaking to get it running right esp for a work saw that needs to start, idle, accelerate, cut at different RPMs and return to idle without reving or stalling.

???? lathe work,any pics..... I´m lost

 

[mtngun]

???? lathe work,any pics..... I´m lost

TW has posted pics of lathe work on other threads. For example see his 460/660 build thread on the Saw Building 101 forum. The machine work is routine, nothing unique to the 361.

http://www.arboristsite.com/showthread.php?t=83777&highlight=

 

[MS390]

TW has posted pics of lathe work on other threads. For example see his 460/660 build thread on the Saw Building 101 forum. The machine work is routine, nothing unique to the 361.

http://www.arboristsite.com/showthread.php?t=83777&highlight=

thanks alot mate

 

[timberwolf]

I'll try to dig out dyno and flow bench tonight, just had a mess of deer and broken ATV taking up some shop space.

When I get to the carb work for the other 361's I'l get some pics of that stuff posted too.

 

[MS390]

youre the man!!!!

I'll try to dig out dyno and flow bench tonight, just had a mess of deer and broken ATV taking up some shop space.

When I get to the carb work for the other 361's I'l get some pics of that stuff posted too.

thanks

 

[timberwolf]

I did get a dyno run done tonight for a stock 361, but still going over the data, upgraded firmware on data logger and it caused some glitches... I'll figure it out.


<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/1SlpLPpo8zg?fs=1&amp;hl=en_US"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/1SlpLPpo8zg?fs=1&amp;hl=en_US" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>

 

[mtngun]

Good to see you using that dyno, after all the trouble it took to make it.

 

[Cornfed]

I did get a dyno run done tonight for a stock 361, but still going over the data, upgraded firmware on data logger and it caused some glitches... I'll figure it out.


<object width="480" height="385"><param name="movie" value="http://www.youtube.com/v/1SlpLPpo8zg?fs=1&amp;hl=en_US"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/1SlpLPpo8zg?fs=1&amp;hl=en_US" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>

Maybe a dumb question, but where does one buy a saw dyno?

 

[mtngun]

Most saw dynos are homemade. There is an outfit or two selling small engine dynos, but they are way out of my price range.

 

[timberwolf]

Anything ready to use is going to start in the $4-5k range and on top of that will need custom gearing and mounting setups to connect a saw to it. I have well over $2500 in mine and that was making a lot of the parts myself and going cheep on the data aquisition end. I think I am going to end up scraping the data unit and software and go to something else, could never get it to run as advertised and their tech support just danced around. Last firmware was supposed to fix it but does not look like it did, plus caused other issues. Oh well...there goes a grand.


Here are a couple different systems.

http://inertiadyno.com/inertia-dyno/inertia-dyno-models-by-stan-hewitt-2010/

http://www.land-and-sea.com/kart-dyno/kart-dyno-price.htm

 

[mtngun]

Sorry to hear about the data acquisition headache, TW. I admire the craftsman ship of your dyno, and imagine the programming must have been interesting, too.

If I ever win the lottery and have the time and money, I'd like to build a dyno, but I was thinking of an old fashioned brake dyno. All you'd need for instrumentation is a tach (already have that, or easy to make a spindle tach) and some sort of force transducer, which could be as simple or as fancy as you wanted. Data collection could be done manually if necessary, though a simple PC data aq would be better. The brake itself would be more challenging. but I was thinking to try an automotive disc brake. Dunno if it could handle the rpms, and obviously it would overheat after so long, but it might tolerate a short dyno run.