HAILERS

I found in the General Rotary Tech seciton a better way to find TDC than what is known as the sparkplug method used by some.

A fellow posted the following URL and it seems to be a much better way to find TRUE TDC vs a ballpark tdc using the sparkplug method. The url is: http://members.optusnet.com.au/~onec...-%20part%20one

Just in case there's someone out there that is not familiar with the sparkplug method, it's found at the BOTTOM of this url: http://www.teamfc3s.org/info/articles/demystifying.html That'll get you in the ballpark, but won't get you a hotdog and popcorn to go with it. You need the first url to get the whole package. humor

J-Rat

iTrader: (2)

Book marked that bad boy!

HAILERS

J-RAT.....uhhhhh, errrrrr, ahhhhhh, I think I posted too fast. I should have done it first then posted. I sorta disagree with what he's saying about the four bolts that hold the pulley to the hub. I might try again tomorrow after work. I agree about the keyway being at 90 degrees when at top dead center but have doubts about what he says the bolts align with. Maybe on his RX-4, whatever that was, it worked but my pulley attach bolts are offset and don't point AT the keyway or the fixed pointer. Maybe I need to revisit it tomorrow and give it another try.

J-Rat

iTrader: (2)

Oh great..

Way to suck!

scathcart

Our pulleys bolt alignment holes are not evenly spaced, the bolt marking will not work.

HAILERS

Yup. That's why I stopped reading that url. But, I have a compass, divider, straight edge and a sharp pencil AND at least three spare/oddball pulleys, spare engine and spare eccentric shaft One of which has that rivet in it attaching it to the pulley boss (actually I drilled it out several years ago). Now I think THAT pulley has four evenly spaced holes. I won't know til the morn.

And as I wrote in the General Rotary section, I turned the engine over and poured oil in the lead sparkplug holes with the engine at approx TDC. Turned the flywheel back and forth to determine the highest level and noted where one of the 24cas teeth was each time I did it. I have repeatability doing that.

But, I'm gonna use the compass, dividers and sharp pencil and find TDC using the woodruff key as a benchmark. Then compare my oil level results with that......divide by four, square that number and add the number of eggs the chicken laid last night to compute TDC. humor

Yeah, I read Scathcat's remarks on that old post about how you made a ????? (forgot the term right now, template?) to determine TDC and degrees before and aft of TDC

I've no idea why three out of my four pulleys have slightly different hash marks. All 13B. If 12A carb they'd have the LEAD mark at TDC and Trail at 20, so you'd think if I had a 12A carb pulley the marks would be further apart. They aren't.

scathcart

Its a degree wheel, modified to fit the rotary. Pretty useless if you don't already know TDC... you have to first be at TDC before you can attach something that assigns degrees of rotation to the eccentric shaft.

Fortunately, locating TDC exactly with an engine dissassembled is easy... all you need is a dial indicator, and then you can attach your degree wheel, and then never have to find TDC again.



As a side note, you cannot use the calculation of the point between the spark plugs as an indicator of exact top dead center. With the rear rotor's apex seal directly between the two spark plugs, you will not be on exactly TDC on the front rotor.
Proof: The S5 Leading spark plug is "lower" in the rotor housing than the S4. The trailing spark plug position is the same position. The distance between the two is longer on the S5, so divide that by two and move that distance down from the trailing plug, and your rear rotor moves farther downward on the S5 than it would on an S4.
Not that anyone thought that method to be accurate to begin with....

HAILERS

88888888Fortunately, locating TDC exactly with an engine dissassembled is easy... all you need is a dial indicator, and then you can attach your degree wheel, and then never have to find TDC again.******************************************** ********************************
I've a dial indicator, a engine that is apart and to dumb to figure out how to use the two to find TDC. Please give me a clue.

Maybe put the eccentric shaft ONLY in the front side housing and rear side housing......turn the shaft til the dial indicator shown the lobe for the front rotor is at it's max travel to the left of the engine and make my mark? OOps, that would be front side housing WITH the cover attached and the pulley loosely installed.