Settings Base Timing on an S4/S5 RX-7

[HaveYouSeenAWizardSleep]

On my RX-7 there are two timing marks:

 

Leading: 5 degrees ATDC

Trailing: 20 degrees ATDC

 

When calibrating base timing / offset, I had a few questions as I’ve heard a few things that seem quite contradicting.

 

1. Do I have to alter my rotary split table before entering the calibration table?

 

2. When setting base timing do I just enter in a value “-20.0”, attach my timing light to the L1 (Leading 1) spark plug wire, and then adjust the offset until the light illuminates when the -20 degree mark on the pulley hits the timing mark on the front cover.

 

I’m fairly new to all of this, so still trying to get a solid understanding of all of this. Just got my engine started by locking my my timing to -20 BTDC and setting my offset to 180 degrees which was a rough guess but still gave the engine the ability to run regardless.

[Adamw]

On the rotaries using the leading wasted ignition mode it is important to verify the timing of L1 and both trailing plugs as it is possible to end up with the trailing 180deg out which can cause detonation.

Since you have two marks this makes it fairly easy.  Adjust your whole timing split table to -15.  To do this, click at the grey square at the top left corner to select the whole table, then type "=-15" and hit enter.   With the engine running, open the set base timing screen and lock the timing to -5.  Clip the timing light on L1, and check that the front cover pointer lines up with the yellow mark - if not then adjust your offset up or down until it does.

Next with the set base screen still open, and timing still locked at -5, move your timing light to T1, the red mark should line up.  Then move timing light to T2, the red mark should still line up.  If the red marks cant be seen when you are checking the trailing plugs then it means you are 180 out so just subtract 180 from your offset and check again.

[HaveYouSeenAWizardSleep]

25 minutes ago, Adamw said:

On the rotaries using the leading wasted ignition mode it is important to verify the timing of L1 and both trailing plugs as the engine as it is possible to end up with the trailing 180deg out which can cause detonation.

Since you have two marks this makes it fairly easy.  Adjust your whole timing split table to -15.  To do this, click at the grey square at the top left corner to select the whole table, then type "=-15" and hit enter.   With the engine running, open the set base timing screen and lock the timing to -5.  Clip the timing light on L1, and check thast the front cover pointer lines up with the yellow mark - if not then adjust your offset up or down until it does.

Next with the set base screen still open, and timing still locked at -5, move your timing light to T1, the red mark should line up.  Then move timing light to T2, the red mark should still line up.  If the red marks cant be seen when you are checking the trailing plugs then it means you are 180 out so just subtract 180 from your offset and check again.

Awesome! Very insightful, thanks again Adam you’ve been a huge contribution to helping out. Hopefully these forum post stay up for other FC owners to see planning on going with the Link, lots of useful things I’ve learned from you!