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Ignition advance curve on 3.2 with carbs?

Posted: Mon Apr 22, 2019 6:55 am
by greg356a
Hello,
I could do with some guidance, I have fitted a fully programmable 123/ignition distributor to my 3.2 which runs carbs with 38mm chokes. I am not sure what the best timing curve would be? Thought I would start with,
RPM BTDC
1000 - 10
1500 - 14
2000 - 20
2500 - 25
3000 - 30
3500 - 32
4000 - 32
6000 - 32

There are two switchable programs and wondered if maybe I should be more aggressive? Maybe 35 at 3500 rpm?

I have read countless posts and everything seems to be different given the many parameters. I cant find a curve for 3.2 only lower CR 3.0 SC and 2.7 S etc on carbs. The original factory data map looks way to complicated. Pelican posts all seem to be on lower octane fuel.

I need to get it running well enough to allow me to get it to the rolling road. No ECU when I fitted the engine to my speedster and I love the sound of the induction roar.

Guidance really appreciated.

Re: Ignition advance curve on 3.2 with carbs?

Posted: Mon Apr 22, 2019 8:28 am
by 911hillclimber
I have a stock 3.2 on PMO carbs too and the distributor is an RS 2.7 spec, no vac advance.
Runs really hard, no flat spots etc and good cold start (for carbs) and perfect instant hot starting.

I have no idea on the advance mechanical curve/rpm but if you wish can find you the distributor spec if I look on the engine.

What do 123 say? Isn't there a 'get you going' curve so you can get it to the rollers for fine tuning? you only need to cruise there and hopefully blast back!

Image

Re: Ignition advance curve on 3.2 with carbs?

Posted: Mon Apr 22, 2019 8:40 am
by Gary71
I know it's has different capacity, compression ratio, cam timing etc but for reference this is the provisional 3D map I ended up with when my 2.4T was (briefly!) running EDIS and a Megasquirt ECU:
Image

Your numbers should get it running well enough for a trip to the rollers.