Thoughts about ignition chips

[David Luciani]

"So I guess the way to adjust the timing would be to vary the position of the coil relative to the flywheel. But to measure the timing you would have to calibrate the flywheel, then run the engine with the shroud removed and check it with an inductive timing light"

EXACTLY THAT.
except the engine need not be running to set timing.
i never used to bother with setting up timing top dead center and was very comfortable with just using coil "sight marks" setting the coil for about forever.
but lately i've gone back to being precise.
mostly Scott K ruined my day pointing out some of the cranks are cut differently year to year
SteveO then further wrecked my day showing the typical flywheel variance allowed in factory tolerances back in the day.
With most of the motors being of unknown Factory Original Purity there is an excellent chance any motor new to you could be a composite of years and parts.

Since Mcculloch changed flywheel timing slots and timing keyways on cranks it is possible to make a really badly timed motor.
So any method of timing that doesn't determine top dead center of the actual motor , as currently assembled ,may result in a poorly running motor.

Occasionally that can ruin a piston ,or more likely , wreck your weekend of fun driving with endless bad starts.


to set and or determine top dead center and set your timing precisely you want to build a little dohicky out of a used spark plug and bolt.
the bolt will go through the spark plug body and be adjustanble.
once you've determined top dead center for the engine you can easily set timing using a cheap plastic compass.
i think it was scott that posted exactly how in a thread that now is somewhere in the old forum copy.
it'll be a little hard to find but i'll take a look.
i'm pressed for time right now but i'll dig up the thread about setting timing on a two stroke later on this week..

[ted johnson]

You can buy a good degree wheel off eBay for $15.00. I had an old one here, and JB Welded a nut onto it to screw onto the end of the crank. I drilled the nut thru a flat and tapped it No. 10-32 for a nylon tipped set screw so I could lock the degree wheel at TDC without buggering the crank thread. It'd be even easier on a Mac, just get a couple of 3/8-24 jam nuts and glue one to the wheel. You can jam the other tight enough with your fingers to keep the wheel from slipping. The reason for the set screw on mine is that it's hard to find 7/16-20 LH jam nuts for West Bends. I have a pointer I made with an old coupling nut I drilled thru the flats for a pointer. I Loctited a stud in one end of the jam nut and hold the pointer wire in the drilled hole with a thumb screw. I screw the stud into a PTO boss hole and the coupling nut assembly puts the pointer at just the right position for the diameter of my degree wheel. The rest is standard practice for determining TDC. The fun part is determining where the stator needs to be to time a PVL on a Bender. Thanks to Dave Bonbright for that info! I actually just this morning received my self powered timing light from Jeg's, so I will probably begin timing the PVL's that way. TJ

[Bill Peck]

"So I guess the way to adjust the timing would be to vary the position of the coil relative to the flywheel. But to measure the timing you would have to calibrate the flywheel, then run the engine with the shroud removed and check it with an inductive timing light"

EXACTLY THAT.
except the engine need not be running to set timing.
i never used to bother with setting up timing top dead center and was very comfortable with just using coil "sight marks" setting the coil for about forever.
but lately i've gone back to being precise.
mostly Scott K ruined my day pointing out some of the cranks are cut differently year to year
SteveO then further wrecked my day showing the typical flywheel variance allowed in factory tolerances back in the day.
With most of the motors being of unknown Factory Original Purity there is an excellent chance any motor new to you could be a composite of years and parts.

Since Mcculloch changed flywheel timing slots and timing keyways on cranks it is possible to make a really badly timed motor.
So any method of timing that doesn't determine top dead center of the actual motor , as currently assembled ,may result in a poorly running motor.

Occasionally that can ruin a piston ,or more likely , wreck your weekend of fun driving with endless bad starts.


to set and or determine top dead center and set your timing precisely you want to build a little dohicky out of a used spark plug and bolt.
the bolt will go through the spark plug body and be adjustanble.
once you've determined top dead center for the engine you can easily set timing using a cheap plastic compass.
i think it was scott that posted exactly how in a thread that now is somewhere in the old forum copy.
it'll be a little hard to find but i'll take a look.
i'm pressed for time right now but i'll dig up the thread about setting timing on a two stroke later on this week..

I have the whole piston stop and degree wheel rig and have no problem setting my timing with points. I'm trying to understand how to set the timing with a module when it seems to be dependent coil position vs. magnet position. Is there a way to measure where the module tells the coil to fire without the engine running?

[David Luciani]

yep.
remove spark plug. install plug into plug boot.
spin motor while holding plug on ground. jump about ten feet make bad language and think operation through a little better.
at least that's how i recall my first try.

a far better way is to ground the plug while installed in the boot find the spark zone.
when you have the right area you can rock it by and make a spark each time. set timing light up ( a flashlite wired in here works fine.) point lite at degree wheel rock past spark point till you see enough to determine timing.
or lightly oil cylinder remove plug set up timing light and spin with small drill to determine timing while dry.
be sure degree wheel is firmly fixed to crank or duck (that was another time i had brain dead fun!!)
you'll find moving the coil around will change your timing.

[Bill Peck]

yep.
remove spark plug. install plug into plug boot.
spin motor while holding plug on ground. jump about ten feet make bad language and think operation through a little better.
at least that's how i recall my first try.

a far better way is to ground the plug while installed in the boot find the spark zone.
when you have the right area you can rock it by and make a spark each time. set timing light up ( a flashlite wired in here works fine.) point lite at degree wheel rock past spark point till you see enough to determine timing.
or lightly oil cylinder remove plug set up timing light and spin with small drill to determine timing while dry.
be sure degree wheel is firmly fixed to crank or duck (that was another time i had brain dead fun!!)
you'll find moving the coil around will change your timing.

Sounds like a winter project! BTW Dave, Avon is looking better for me. I just have to get psyched up for the 6 hour ride.

[Terry Sullivan]

Bill,

I can't think of a good way to measure, or adjust where the module will fire without having a rig similar to the one Scott built.  I don't worry about it, as I have not had any problems with timing and I am not a hard core racer.
Just an old geezer reliving my childhood.

t

[David Luciani]

Sounds like a winter project! BTW Dave, Avon is looking better for me. I just have to get psyched up for the 6 hour ride.

same time frame for me but i go every year. scott runs one of the best events in VKA and is the East Koast King of vintage events!!!


Save
Save