Old McCulloch with Pipe

[chy_farm]

Making an exhaust port of a pipe seems always to be tricky to me, since the port at the engine side is most always rectangle while the sectional shape of pipe is round, so we have to make a 'converter' , I call it so, to help the high temperature gas flow going as smoothly as possible at this part.
Here showing the muffler from 740, the flange is cut apart and sitting in the left which is to be used for this pipe also as a flange. ;


Make a rectangular 'pipe' which has the same length for the four sides of this rectangular exhaust port.;


Weld them together. ;


Give modification to the shape. ;



The circumference of this round end should be the same as that of the pipe we are going to build. ;


Chy

 

[paragonbuilder]

Good evening Steve, some years ago I found a program scripted in assembly language for the PIC, a micro controller I mentioned above, here quoted the header of this program and the link to it.
;***************************************************************************
;******
;****** Digital ignition for 2 stroke engines. SPORTDEVICES 1/9/2005
;******
;******
;****** Digital parts: PIC16F84
;******
;******
;****************************************************************************

list p=16F84a
#include p16F84a.inc
radix dec

__CONFIG _WDT_OFF & _XT_OSC
;******
;****************************************************************************

(link here)
http://www.sportdevices.com/ignition/ignition16.asm

I think we have to give some modification to this, hope you like it!
As far the adjustable version for this program, not impossible but need some outer terminal to input new data, sounds better if iPhone or some other interface were available in this purpose! But I am not so skilled to accomplish this goal though, lol.
Chy

@malk315

Do you understand this?


Sent from my iPhone using Tapatalk

 

[paragonbuilder]

Making an exhaust port of a pipe seems always to be tricky to me, since the port at the engine side is most always rectangle while the sectional shape of pipe is round, so we have to make a 'converter' , I call it so, to help the high temperature gas flow going as smoothly as possible at this part.
Here showing the muffler from 740, the flange is cut apart and sitting in the left which is to be used for this pipe also as a flange. ;
View attachment 78052

Make a rectangular 'pipe' which has the same length for the four sides of this rectangular exhaust port.;
View attachment 78053

Weld them together. ;
View attachment 78054

Give modification to the shape. ;
View attachment 78055


The circumference of this round end should be the same as that of the pipe we are going to build. ;
View attachment 78058

Chy

Nice work Chy!


Sent from my iPhone using Tapatalk

 

[malk315]

@malk315

Do you understand this?


Sent from my iPhone using Tapatalk

Hey Dan-

It's code for a PIC microcontroller which are even simpler computers than the thing I used for the dyno.

Looks like it reads RPMs by reading a Hall sensor like my dyno code does and it outputs a pulse to trigger a spark to fire the ignition with different delays prior to firing for RPMs between 1-5000, 5000-15000, and over 15000 it looks like it doesn't fire (an RPM limiter I think is what that does).

With the right micro controller and hardware for the hall sensor input and whatever is used to control the spark (output), this looks like it adjusts ignition timing based on RPM in a simple range as I mentioned above and serves as electronic ignition based on RPMs instead of the traditional magneto like we're used to where it fires when the flywheel magnets pass the coil.

Sounds a lot like what you and I had talked about to measure the advance curve of a particular coil that would have been to help out our friend from the north central portion of the country (I don't want to say who in case you still wanted to someday try and surprise him!) but instead of just measuring advance curve it actually does the ignition timing. I'm guessing if you varied where the HES passes the sensor on this, you are adjusting the timing -- make it easy to move the magnet a few degrees either way and instantly try different ignition timing for your saw.

This all after a quick look at the sourcecode and what I'm thinking is going on. I could be wrong here! I'm just a third idiot of 2 idiots logging fame....

Cheers Gentlemen.

p.s. I have been flat out with day job, outdoor networks for campgrounds moonlighting job, treework on weekends, and family commitments. Dan I've got that 262 from MN heading this way and I'll get parts for that 365 and let's setup a time for a little bench work if yer up for it! You can use the 262 including the 87 carb for whatever experiments you have in mind! I'm happy to share my toys

 

[malk315]

Nice work Chy!


Sent from my iPhone using Tapatalk

Oh and This --^^^^^

That mac is SWEET. Reminds me of this day:

 

[chy_farm]

Hello Malk, nice video is he you? A tad heavy but I love gear drive too, here is mine;


A little older than that seen in your video.

Nice illustration on the assembla code. They are tricky but I love their speed in operation.
Have a nice day/evening.
Chy

 

[malk315]

Hello Malk, nice video is he you? A tad heavy but I love gear drive too, here is mine;

View attachment 78124
A little older than that seen in your video.

Nice illustration on the assembla code. They are tricky but I love their speed in operation.
Have a nice day/evening.
Chy

Yup, that is me! But not my saw... I wish. That saw belongs to the legendary @leeh
Hopefully I got his username right.

Cheers!

Sent from my XT1585 using Tapatalk

 

[chy_farm]

Yup, that is me! But not my saw... I wish. That saw belongs to the legendary @leeh
Hopefully I got his username right. Cheers!

I think I know him at the Chainsaw Collectors Forum, he is known as one of the most serious patients suffering the chainsaw disease. Recently he seems so serious to got a couple of very very old Jonsereds, a green XB and a red XD.
Anyways a good saw hoarder he is! Say good words to him, lol.
Chy

 

[chy_farm]

The lead part from the converter to the pipe was also made from 0.5mm thick steel sheet. Their circumferences are the same.



Paid a lot attention to this welding.


Repeat cut and weld to form a better curb to the direction designed.


Oops starter handle is going to touch the pipe, seemed to need some shield for this part.




Chy

 

[Lightning Performance]

Maybe you can run the hall PIC via WiFi on an Apple or Android system? A transmitter on a coin cell should do it. Getting the softwares to chat with eachother will be the trick.

 

[chy_farm]

Maybe you can run the hall PIC via WiFi on an Apple or Android system? A transmitter on a coin cell should do it. Getting the softwares to chat with eachother will be the trick.

Yes lightning, that sounds very nice. But an issue is that I yet know much about the network linkages for these things....
Chy