I have potentially a dumb question.

I understand that keyway to the passenger side (9 oclock position) is TDC, but doesn't e-shaft have to turn 3 times to completely 'reset' each rotor? It seems I will be right only 33% of the time if I just depend on the keyway to the 9 o'clock position method to reset my TDC. My oil pan is off, and I'm using custom pulley which has no marks. I really wish to resolve this now before I start to put the engine back in the car.

I also wanted to ask what would be the best way to mark my custom pulley hub to set the timing correctly with microtech while tuning. I'm currently just eye-balling keyway at 9 o'clock position. and I don't know how to mark my ATDC mark accurately for 20B without the original pulley. I wish there was a more reliable way to set it correctly rather than just carefully eyeballing it.

Thanks in advance.

 

Actually, I was not aware of the 9 o'clock method. The way I did mine was to get an apex seal between the leading & trailing plug holes. while carefully looking at the S4 pulleys I have on my engine. To this day, I still don't understand how it works reliably, but it apparently does...

Once I found TDC, I filed a small groove in the pulley to mark 0 degrees and did the same to the stock leading and trailing marks, then painted each a different color, red and yellow like the stock marks, with 0 degrees being blue.

What brought this on? Stabbing the CAS

I'd highly advise picking up a S4 main pulley in the classifieds section, timing your engine with it, then transferring the timing marks to your aftermarket pulley. The rule of thumb is that one often can't even GIVE away S4NA parts, so the cost will be minimal. I would imagine that you could find one for $5-10 shipped.

 

Dont worry about the whole crank has to spin 3 times etc.
bring the crank round to have the front keyway at 9 o'clock position.
check that your rear counter weight has the tip pointing up between the two upper most through bolts and the rounded side of the counter weight pointing to the spark plug side.
now just to double check it all use some welding wire and gentle poke it through the front rotor housings spark plug holes, you should hit the rotor face almost immediately.

Using a degree wheel mark your front pulley with a scribe and vivid lightly until your sure you have it 100%

hope that helps

 

TDC for each rotor face starts again with each e-shaft revolution, the number of rotors is irrelevant. time it the same way you would a 2 rotor engine.

if you don't want the guesswork just pick up a RB pulley, it will have a TDC stamp on it but be aware that is also has ATDC and BTDC markings with no numbers(i also don't believe they come with a spec sheet of which stamp relates to what degree but the listing page gives the numbers from left to right).

 

just to add, you would be correct if the rotor only had one face, it does take 3 turns of the eccentric shaft for a given rotor face to go from TDC to TDC, however since there are THREE faces on a rotor it means that there is a rotor face on TDC every time the eshaft goes to 9 oclock. and like Mr Evolution says, the number of rotors is unimportant

with a piston engine you have to figure out if its TDC intake, or TDC compression, but with the rotary you don't because these two things happen in different physical locations.

 

Thanks guys! Will try this tomorrow!

 

Just in case anyone finds this during searching
https://www.rx7club.com/20b-forum-95...quest-1091664/