timing

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W5R

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What is the best way to time an animal without a degree wheel or timing light? I am thinking someone posted before a way to time them by how far the piston is in the hole, but have not been able to find that post by searching. This is a Gen 5 animal, flathead crank and stroker rod, dome piston, with the Briggs PVL flywheel and blue pvl coil, trying to get to 32-34* timing. If anyone knows a way please let me know.

I am thinking if I were to get the piston at top dead center, then put it in the hole so many thousandths, I could line the magnet up with the coil leg to set the timing, problem is I don't know how far in the hole to put the piston before top dead center, or which end of which magnet I should line up with the coil, if that makes sense. I am hoping someone who builds alot of these engines would be able to answer that and get me close since these engines are pretty consistent from one to the next, unlike the clone and predators. I'm not very familiar with the animal timing yet myself, still trying to learn that part. Can't just use a key since the keyway on the flathead crank doesn't line up with the animal flywheel, or is it even close. Is my only options here to get a degree wheel or find a timing light?
 
W5R said:
What is the best way to time an animal without a degree wheel or timing light? I am thinking someone posted before a way to time them by how far the piston is in the hole, but have not been able to find that post by searching. This is a Gen 5 animal, flathead crank and stroker rod, dome piston, with the Briggs PVL flywheel and blue pvl coil, trying to get to 32-34* timing. If anyone knows a way please let me know
Click to expand...
First you need to know how far in the hole matches the degrees you want of timing. Most people did it all the time with Rotary and Reed valve two cycle engines. We never talk in degrees, we always talked .000's in the hole.

I would think, if you had an engine where you knew what the timing was in degrees, if you measured how many .000's in the hole the piston was, you could stop using a degree wheel and just measure the piston position in the hole. Of course you'll need a dial depth mic and holder.

I have a spreadsheet that gives piston travel versus degrees. Lots of places to get that. All you need to know is the stroke and the length of the rod.

An example; clone stroke equals 2.123", rod equals 3.308". 32 degrees of timing equals .209" in the hole. Easily verified if you've used a degree wheel on an engine and then check the corresponding in the hole measurement. I can absolutely guarantee that 32 degrees is .209" in the hole.
.000" degrees
.185 30.0
.197 31.0
.209 32.0
.222 33.0
.235 34.0
.249 35.0
.262 36.0
.276 37.0
.290 38.0

Spreadsheets are useful.
 
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Measure the flywheel diameter accurately. Divide by 360 then you have degrees per inch. Or parts there of. It gets more complicated after this .
Degree wheel or Al's spread sheet is much easier.
 
flattop1 said:
Measure the flywheel diameter accurately. Divide by 360 then you have degrees per inch. Or parts there of. It gets more complicated after this .
Degree wheel or Al's spread sheet is much easier.
Click to expand...
Actually; diameter "x pi" divided by 360 = inches of circumference per degree of rotation.
 
Find tdc mark flywheel point of tdc and block.
Measure the amount needed for your degree's roll it back measure your in the hole distance.
Pop flywheel set in the hole and flywheel .
Double check.
 
flattop1 said:
Find tdc mark flywheel point of tdc and block.
Measure the amount needed for your degree's roll it back measure your in the hole distance.
Pop flywheel set in the hole and flywheel .
Double check.
Click to expand...

Do you know how many thousandths in the hole is equal to 1 degree of timing?
 
W5R said:
Ok so that tells what point of the magnet fires under what point of the coil, but it doesn't say where which magnet will be at tdc or anything to tell me where I need to set the flywheel to get 30* BTDC
Click to expand...
You turn the engine to 30* BTDC and set the magnet to the instructions.
 
Ok that makes sense Al, thanks. Do you know how to convert degree's to in the hole measurements? Such as 1 degree is equal to X amount in the hole? What i mean is, say if i were to put the piston at TDC, and wanted to get it to 30*, and each degree was say .005 in the hole, i would put the piston at .060" in the hole to be at 30*, correct? Not saying those numbers are accurate, just an estimate. I have dial indicators just no degree wheel or timing light at the moment
 
W5R said:
Ok that makes sense Al, thanks. Do you know how to convert degree's to in the hole measurements? Such as 1 degree is equal to X amount in the hole? What i mean is, say if i were to put the piston at TDC, and wanted to get it to 30*, and each degree was say .005 in the hole, i would put the piston at .060" in the hole to be at 30*, correct? Not saying those numbers are accurate, just an estimate. I have dial indicators just no degree wheel or timing light at the moment
Click to expand...
Pistons don't move an even number of thousands per degree of rotation. You need something that tells you how many thousands in the hole equals how many degrees, I have that. You need to know the stroke and the Rod length center to center.
For instance, let me give you the number for a clone.
30 deg BTDC = .185" in the hole.

I'm sure you can find something on the net that will get you this math.
 
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alvin l nunley said:
Pistons don't move an even number of thousands per degree of rotation. You need something that tells you how many thousands in the hole equals how many degrees, I have that. You need to know the stroke and the Rod length center to center.
For instance, let me give you the number for a clone.
30 deg BDTC = .185" in the hole.

I'm sure you can find something on the net that will get you this math.
Click to expand...

doesn't your spreadsheet have the math?

For those not wanting to do the kinematics the equation is:

H = (S+R) - S*cos(theta)+R*SQRT(1-(S/R)^2*sin(theta)^2)
Where:
H = amount in the hole
S = Stroke length
R = Rod length
Theta = degrees BTDC
 
alvin l nunley said:
Yes it does, and I give it away for free, but nobody seems to want it. The page is called " degrees of travel" and you can set the resolution down to .1 degrees of rotation.
Click to expand...

Brings back memories - I noticed it when I first got your spread sheets, and it took me back to 1958 and age 14, when I learned to time racing motorcycles this way, with a piece of tissue paper trapped between the points on the magneto - you pulled very gently on the tissue paper as you rotated the mag (after first setting the piston the correct distance in the hole) to detect when the points started to open.

I also learned that you don't need expensive or complex instruments to set piston depth in the hole. We established TDC, then stuck a regular yellow wooden pencil down the spark plug hole and marked the pencil with a blade (an Exacto knife is excellent) to show where it was even with the top surface of the spark plug hole in the head. Then we took a set of calipers and set it to the amount the piston should be in the hole, set one jaw of the caliper at the TDC mark, and made a second mark above the first one by putting the blade against the other caliper jaw and taking another shallow slice at the pencil. It usually took a few tries bumping the engine to turn it over slightly, but you bumped it down to the upper mark, and maybe back and forth a couple of times to get it exactly on the mark, and you were good to go. Worked fine for us and saved fabricating jigs to hold a dial indicator.
 
alvin l nunley said:
Pistons don't move an even number of thousands per degree of rotation. You need something that tells you how many thousands in the hole equals how many degrees, I have that. You need to know the stroke and the Rod length center to center.
For instance, let me give you the number for a clone.
30 deg BTDC = .185" in the hole.

I'm sure you can find something on the net that will get you this math.
Click to expand...

3.625" rod length and 2.437" stroke
 
Outrider said:
Brings back memories - I noticed it when I first got your spread sheets, and it took me back to 1958 and age 14, when I learned to time racing motorcycles this way, with a piece of tissue paper trapped between the points on the magneto - you pulled very gently on the tissue paper as you rotated the mag (after first setting the piston the correct distance in the hole) to detect when the points started to open.

I also learned that you don't need expensive or complex instruments to set piston depth in the hole. We established TDC, then stuck a regular yellow wooden pencil down the spark plug hole and marked the pencil with a blade (an Exacto knife is excellent) to show where it was even with the top surface of the spark plug hole in the head. Then we took a set of calipers and set it to the amount the piston should be in the hole, set one jaw of the caliper at the TDC mark, and made a second mark above the first one by putting the blade against the other caliper jaw and taking another shallow slice at the pencil. It usually took a few tries bumping the engine to turn it over slightly, but you bumped it down to the upper mark, and maybe back and forth a couple of times to get it exactly on the mark, and you were good to go. Worked fine for us and saved fabricating jigs to hold a dial indicator.
Click to expand...

Thats an interesting story, thanks for sharing that. Always liked hearing about the old days before precision measuring tools we have today existed...i still do alot of things sort of like you described
 
W5R said:
3.625" rod length and 2.437" stroke
Click to expand...

Timing Advance 30 Degrees
Piston Position 0.21480 BTDC

With a 2 cycle, most had no idea where their timing was in degrees. It was generally agreed, with a komet, that .085" in the hole was good, and, for most, we didn't know, or care, how many degrees that was. Some ran less (me) and some ran more. Testing proved, or disproved, the final setting. A Motoplat could be set at a wide range of timing points.

Don't try to compare 2 cycle timing with 4 cycle timing, it's two different worlds.

One thing, timing in degrees is necessary if you can't convert degrees to piston travel. Different strokes, along with Rod length, will change the travel distance compared to degrees of rotation. Just a heads up.
 
alvin l nunley said:
Timing Advance 30 Degrees
Piston Position 0.21480 BTDC

With a 2 cycle, most had no idea where their timing was in degrees. It was generally agreed, with a komet, that .085" in the hole was good, and, for most, we didn't know, or care, how many degrees that was. Some ran less (me) and some ran more. Testing proved, or disproved, the final setting. A Motoplat could be set at a wide range of timing points.

Don't try to compare 2 cycle timing with 4 cycle timing, it's two different worlds.

One thing, timing in degrees is necessary if you can't convert degrees to piston travel. Different strokes, along with Rod length, will change the travel distance compared to degrees of rotation. Just a heads up.
Click to expand...

Just a thought, but the .21480 measurement would only be correct if the piston is flush with the deck, wouldn't it? If the piston was down the hole .005 or had .005 pop up that would change the depth at 30*? If my math is correct, then every degree would be .013" of travel (2.437/180)? If so then the .21480 depth could be off by a couple of degrees?

I'm not positive that I'm thinking about that correctly, but it makes sense in my little brain :)
 
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