Timing an unknown 2.5L Twin Plug motor...

[Atomic]

OK guys, I wound up with a 2.5L motor that ran great except for a stumble at 3500RPM at full throttle. Some investigation found that the magnet in the twin plug distributor had cracked. So, I sent the distributor off to be rebuilt and the rebuilder (Dave Jarvis) confirmed the cracked magnet was more than likely my problem. The distributor is now on its way back to me.

All that being said, I don't know where to set my timing once it gets here. I know the motor is 2.5L and I know it was built by Willison Werkstatt in 2013... but they don't keep records and I have no idea how they got to 2.5L in regards to bore and stroke. And, of course, I don't know what compression ratio either...

So, I don't know where to set the timing. I'm thinking the best route would be to set the timing at 5,000rpm at somewhere conservative like 35 to 37-degrees (advance in the twin plug distributor is 28 deg). Take for a test drive and if it doesn't detonate, advance it a bit more. Do this until it detonates and then back off.

Does that sound like a decent plan? Anyone have suggestions?

[gled49]

It should be more like 28* total.

[Atomic]

It should be more like 28* total.

Given that, are you suggesting I set initial (idle) at 0-degrees?

[Richy]

Are you really so clueless ? The purpose of twin plugs is to run less advanced ignition timing . 35 to 37 is not conservative even for single plug ignition timing . Follow gled49 , 28 total .

[Atomic]

Are you really so clueless ? The purpose of twin plugs is to run less advanced ignition timing . 35 to 37 is not conservative even for single plug ignition timing . Follow gled49 , 28 total .

Hey man. No need to get snarky is there? I’ve never owned a twin plug car and you have to start somewhere… So I started by innocently asking a question.

Sincerely hope your day gets better.

[72targa]

Take it easy Richy. This is a learning environment. An apology is in order.

Let us know how things turn out, Atomic.

[Atomic]

Take it easy Richy. This is a learning environment. An apology is in order.

Let us know how things turn out, Atomic.

All good... Everyone has bad days, gets impatient, etc... I'm not sweating it.

In any case, distributor should be here today... I'll report back with how it goes.

[Atomic]

As promised. I’m back with my findings. I went with 26-degrees all in at 6000rpm, took it for a test drive and it felt pretty damn good. No detonation, but the plugs look a little dark. Tomorrow, I’m gonna give 27 to 28 degrees a shot and see what happens.

Thanks for helping a clueless guy richy.

[Richy]

Yes , I should have been more diplomatic , but I did briefly explain twin plug theory , sorry .

[Atomic]

Yes , I should have been more diplomatic , but I did briefly explain twin plug theory , sorry .

Don’t sweat it Richy. All good man. And thank you sir.