Flatheads and Lab/Ocilla Scopes
- Thread starter rockfla
- Start date
Kurt in NJ
Well-known member
I don’t know about lab scope,haven’t tried it.
I do know what happens with a snap on vantage multimeter/scope —- it would work on the model T hand cranking but as soon as it started the vantage started crying and became totally unresponsive and had to be reset by taking the battery’s out.
On the model a it would have to be inside the car and it sort of worked but locked up occasionally but still respond to pushing the buttons.
I do know what happens with a snap on vantage multimeter/scope —- it would work on the model T hand cranking but as soon as it started the vantage started crying and became totally unresponsive and had to be reset by taking the battery’s out.
On the model a it would have to be inside the car and it sort of worked but locked up occasionally but still respond to pushing the buttons.
drolston
Well-known member
You would need a sensor of crank speed. Could be optical sensor looking at a white dot on the crank pulley, preferably aligned with TDC of cylinder #1. Then you would need a sensor of ignition voltage on cylinder #1. With the crank speed sensor as base and comparing to #1 firing, you could see the difference in time between them vary as you vary the rpm and see the effect of spark advance. Once you observe the time difference between idle and a higher rpm where the spark advance kicks in, record the time difference. Take that time delta measurement every 200 rpm up to maybe 4,000.
The time delta converts to spark advance thusly
rpm x 60 = revolutions per second (rps); rps x 360 = degrees per second (dps)
dps x delta Time = delta (change in) degrees, or degrees spark advance from idle.
Do that, and you have your advance curve of degrees advance versus rpm.
If it were me, I would send my distributor to Charlie NY to be sure the advance mechanism (and everything else) is working right, and then time the engine by ear for the altitude, fuel quality, fuel mixture, and everything else that determines how far you can practically advance the timing.
"By ear" starts with setting the timing mark at the center position on the distributor. Then take the car out and floor it in second gear. Should not get pinging or spark knock, which sounds a bit like shaking some nuts and bolts in a can. Advance one mark, two degrees, on the distributor, and test drive again. Repeat advancing until you get spark pinging during your second gear throttle burst. Then back off in one degree increments until it goes away. Then one more degree for a margin of prevention.
The time delta converts to spark advance thusly
rpm x 60 = revolutions per second (rps); rps x 360 = degrees per second (dps)
dps x delta Time = delta (change in) degrees, or degrees spark advance from idle.
Do that, and you have your advance curve of degrees advance versus rpm.
If it were me, I would send my distributor to Charlie NY to be sure the advance mechanism (and everything else) is working right, and then time the engine by ear for the altitude, fuel quality, fuel mixture, and everything else that determines how far you can practically advance the timing.
"By ear" starts with setting the timing mark at the center position on the distributor. Then take the car out and floor it in second gear. Should not get pinging or spark knock, which sounds a bit like shaking some nuts and bolts in a can. Advance one mark, two degrees, on the distributor, and test drive again. Repeat advancing until you get spark pinging during your second gear throttle burst. Then back off in one degree increments until it goes away. Then one more degree for a margin of prevention.
rockfla
Well-known member
Drolston
I have my own Sun 504 SO I can rebuild, time and set the vacuum advance on my distributors with NO issues. The reason I ask IS, my good friend is closing his repair shop after almost 50 years of turning wrenches. He's taking all his shop equipment to his shop at home....He knows I mess with flatheads and he was over testing a few distributors, weights and springs for his race car on my 504 and has expressed and interest in trying to use all his more modern Lab Scope, Ocilloscopes etc etc on tuning and "fine" tuning my flathead's as well as teaching me the how's and why's of how this equipment works performs and the reasons and contributing factors for issues we may find!!!! SO IF possible it would be nice to know, as close to 100% as you can get that ALL the factors of a gas engine are ALL operating at peak and proper efficiency!!!
I have my own Sun 504 SO I can rebuild, time and set the vacuum advance on my distributors with NO issues. The reason I ask IS, my good friend is closing his repair shop after almost 50 years of turning wrenches. He's taking all his shop equipment to his shop at home....He knows I mess with flatheads and he was over testing a few distributors, weights and springs for his race car on my 504 and has expressed and interest in trying to use all his more modern Lab Scope, Ocilloscopes etc etc on tuning and "fine" tuning my flathead's as well as teaching me the how's and why's of how this equipment works performs and the reasons and contributing factors for issues we may find!!!! SO IF possible it would be nice to know, as close to 100% as you can get that ALL the factors of a gas engine are ALL operating at peak and proper efficiency!!!
Last edited:
drolston
Well-known member
Flathead Fever
Well-known member
I used a Sun scope at work for 40-years. Later I bought a working Sun scope for home use for $50.00. The guy said it just took up too much room in his garage. They are mostly used for finding cylinder misfires, comparing the cylinder patterns, not so much for performance tuning.