Hello everyone.

-I have a 3.0 motor that red lines at 7,200 rpm with triple mikuni's

-I do not like the fact the tuner used a stock distributor and set the base timing at 20 degrees. The idle is not the best.

-So I am going to do the electromotive XD200 programmable ignition with Hoke perf. trigger wheel/mount/etc.

-Are there any timing recommendations from idle throughout the rpm range to 7,200 rpm?

Thanks, GI 

20 might be a tad high, but not unreasonable for idle with triples . I would be curious what the mechanical advance is tuned to and if your running vacuum advance?

Timing has many variables but WOT full advance could be anywhere from 30 to 38 degrees depending on CR , cam, fuel grade availability. I’m pretty sure that Rebello curves their distributors for full advance after 3300 or so rpms. Mine comes in earlier with my engine . I am using Megasquirt to control ignition.

In low load areas of my table  I run as much as 45 degrees advance. Not afraid to run high thirties cruising . 

 

No vacuum adv. All mechanical from stock dist. I had a Mallory dist. but the vacuum adv. pot had some issues while waiting almost 6 years for the motor (not Rebello's fault, but the company contracted to restore the car). With triples is there a base timing for idle that is different from the stack setting?

10 hours ago, GIchiro said:

-I do not like the fact the tuner used a stock distributor and set the base timing at 20 degrees. The idle is not the best.

-So I am going to do the electromotive XD200 programmable ignition with Hoke perf. trigger wheel/mount/etc.

Changing to a programmable ignition system will have no affect on your idle quality, unless, maybe, your stock system is a points distributor running a low energy coil.  20 degrees with Electromotive will be the same as 20 degrees with what you have now.

There might be other reasons to go with Electromotive but idle quality would not be one of them.

The carbs are a little rich at idle 12.8:1, so I need to do some jetting too. But, for what I paid, I feel a stock dist. was a shortcut.

So you have a 1973 points distributor and "6 volt" coil?  There are many many electronic ignition system options.

The XDi 200 looks nice but it's a little bit over the top for just fixing the idle quality.

https://electromotive.com/our-products/xdi200-ignition/

I think having greater control over the timing through the rpm ranges may be best. Over the top. Probably not but over cautious, yes.

Do you know that your engine builder didn't give you a distributor tuned for the engine?  You never answered the "what distributor" question.  That coil does not look stock 1973, you might look under the distributor cap to see what's there.  You'll need to learn all about tuning engines with the XDi200.  Could be fun.  

Get some good air filters on that new high-performance engine.  You don't want to suck dust and debris in to grind away at the shiny new surfaces.

12.8 is fine and probably as good as you will do with a performance engine with triples . I run my EFI converted performance L24 at about 13.5. 

What rpms is the idle? What’s wrong with the idle - spitting , popping or just seems high. If it’s a high performance cam then a higher idle might be best - but that can bug folks that are use to a 800 rpm idle. Some times idle is increased for cam oiling with spray bars .

More specific info is needed as far as EXACT info on dizzy type, curve, points or electronic. I imagine that dizzy has been curved if it was set up with 20 initial

How does engine perform otherwise . What’s your mechanical experience with these engines ?

We need as much detailed info as posssible. 

Trying to get information from the engine builder (Rebello) and the z car specialist I hired to restore/build/tune the car has been a disaster for the last 6 years. I am not going to name anyone unless it goes to litigation at this point. The distributor is stock (as I was told by the tuner/Z car specialist), the points are used pertronix and a MSD blaster coil. Previously I had a Mallory vacuum/mech advance with mallory coil. But when you wait over 5 years for your engine to be dynoed/installed the diaphragm can get dry and not function properly. I also have Bill's racing velocity stack covers and K & N filters on the way for everyday use.

 

Edited April 23, 20186 yr by GIchiro
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