Hello, so I’m running the 13b rew front cover on my 20b, utilizing the 13b pulley, and the 13b trigger wheel essentially as a spacer. Doing a first start up tomorrow, my tuner wants a mark placed 180 degrees from the timing mark, so I guess my question is, which one is considered the “timing mark”? There seems to be two notches, one slight notch and one deeper notch, but I guess idk which one is considered the “timing mark”. Also with a 20b, since I’m using a FD front cover and trigger wheel, are the timing marks even relevant? Thanks for any help!

 

The REW timing marks are 5 and 20 ATDC. As long as the pulley hub and wheel are from the same engine, the marks will be accurate. But, I’m guessing, you’re using the 20B hub so all bets are off.

My other concern is that your tuner wants a 180 mark on a 20B. That mark is irrelevant on a 3 rotor.

 

I’m assuming the smaller notch is 5 and the larger is 20? Per his instructions he just says “rotary guys” To make the mark, but I think he usually deals with 2 rotors. What is the reason for the 180 mark? Just curious.

 

with any ECU you need to wire up and configure the software, you NEED to verify the timing is correct on each rotor.
a 2 rotor has the two rotors 180 degrees from each other
the 3 rotor is 120

so you need to verify that when the engine is on TDC #1 rotor, that the mark lines up (or -5 and -20), and then you can make marks 120 degrees apart for the other two.

 

you need to start with a TDC tool before the engine goes together, but are now at the “rolling the dice” stage like most do

 

When did REW have a 5ATDC timing mark ? lol

They only have 20ATDC

 

Truth. My bad. 😉

 

as referenced in the post above, once true TDC is established, then determining and setting any other degree mark you want on the pulley is a relatively simple task.

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Thank you guys for all of the information! Very helpful. My builder ended up showing me a video to find TDC on 20b. (Non-13g crank using fd trigger wheel and front cover) but he said starting at the finger that sticks out count 4 spaces clockwise, then go 180 degrees from the inside of the 4th space. We dld it with a degree meter and visual inspection of the leading plug rotor 1 and it seemed pretty spot on!