I used a GM HEI distributor with coil-in-cap for years with no troubles. It started giving me trouble, so I decided to try something new.

I tried running the Crane XR-i on a newly rebuilt points-style distributor. It worked, but spark output was a bit weaker than expected. Had to reduce plug gaps to .035 to make it run.

So I upgraded to an MSD 6AL ignition, triggered by the same XR-i unit. Spark output was obviously increased. I was able to increase plug gaps to the .045 that I ran with the HEI. I then increased the gap to the .050 recommended by MSD.

It still ran, but unfortunately, the distributor had no way to limit the amount of mechanical advance, and I couldn't find any bushings for it locally. I refuse to spend $9 for a bushing plus another $9 shipping for a dinky kit so I can get a $0.25 bushing. So I was forced to run it with only 8 degrees initial advance in order to limit total to 34 degrees.

I could never get it to idle properly (see this post) (http://www.chevelles.com/forum/ultimatebb.php?ubb=get_topic;f=4;t=018898) .

Well, the MSD 6AL came with the harness to use the HEI's mag pickup as a trigger. Since, as Von suggested earlier, I'd already optimized the timing curve on my HEI distributor (through lots of trial and error research), I decided to put it on to give it a try (it's now also modified to use the MSD Blaster-2 Coil).

This distributor is set up with 18 degrees initial to give 34 degrees total.

The idle is back to normal, vacuum is back up, and vacuum advance is back on the manifold port, where I've run it for years with good economy and no problems.

It's certainly nice to have the car running well at idle again. Now I can drive around town without having to feather the throttle every time I stop.

I plan to find or make a limit bushing for the other distributor so I can get the same initial advance without detonating on the high end. I also plan to test it with a Unilite module as a trigger.

And, to further sweeten the deal, I'm getting an MSD Pro-Billet distributor with everything I'll need to optimize the curve on that one. When I'm finished I'll have three functional distributors. Fun huh? :D

Of course, as usual, I'll keep everyone posted on what happens.

Cheers! graemlins/beers.gif

Good stuff to know. I'm gonna have an engine very similiar to yours and just purchased a vaccum dist.(none on there before)..how much initial timing to you get with the vaccum hooked up to manifold and how much does the can provide? Just want a good baseline to start at. With my 16 can I'm gonna be around 27 initial which seems like a bit much.

With 18 initial and the vacuum advance limited to 14 degrees, I'm running 32 degrees advance at idle in park. Of course the vac advance isn't pulling while cranking, so it doesn't drag on the starter.

Every combo is different. I suggest trying it with both ported and manifold vacuum sources to see which one you prefer. I'm always changing things to see what happens. If I kept a log book, it might be worth publishing. Nah. It's already published on TC somewhere anyway. And since none of it is related to drag racing, it's considered unimportant to many in the Performance forum.

So other than the fact that the distributor itself needed some tweaking with a bushing to limit mechanical timing and be timed where you wanted it, what was your final impression of that Crane XRi? Worth it or Worth"less"?

Im still on the fence about it, and am curious as to what you think of it since all is said and done and youre back to the HEI.

Honestly, I think I'd have been better off triggering the MSD with points. But then the original plan didn't call for an MSD. Just a points-to-electronic conversion.

I should have hooked up my oscilloscope to see what kind of signal it was putting out. It's supposed to work like a magnetic pickup. To me, however, a points cam is too "vague" for a good mag-pickup signal. A scope on a mag-pickup will draw a picture of the metal object that's passing in front of the pickup. I've looked at lots of Caterpillar flywheels like this over the years.

Too late now. The Crane unit is not going back on.

I'm looking forward to trying the Unilite on the same distributor to see if there's any difference.

And the really weird thing is that I can back off on my HEI distributor to the same 8 degrees initial timing without the same idle issues. I think it's a triggering issue, but I don't have enough evidence to be 100% certain.

I have thought about putting an MSD on my points system, but quite frankly didnt know if it was worth it, so I was looking into the Pertronix (which I learned was apt to fail out of the blue, through some research) or something like the Unilite or this Crane XRi. After seeing teh XrI, I was intrigued because it seemed like it would respond "better" (utilize it better) to something like the MSD (if it worked "as advertised"), but apparently not :( . IMHO, It (XRi) really should have worked well on its own..

I would be inclined to agree with you that it must be a triggering issue...If you can run the same timing with the HEI and not have the same issues, it more than likely seems that it WOULD be a triggering issue with the Crane unit.

Thanks for posting follow ups!

Just FWIW I had points triggering an MSD 6AL for a while. It wouldn't go over 5000 or so until I installed a new condenser. Then it was OK for a short time then back to the old samo. I've used a Pertronix 1181 (the original design) to trigger the MSD for 4 years without problem. I think most of the Pertronix failures you hear of are the newer designs (lobe sensing and spark enhancing). The 1181 is still available and many people have had years of trouble free use out of them. DZAUTO is one.

Take the condenser out! I've seen electronic conversions with points (not MSD) that would barely run with the condenser in. It's not needed with the MSD anyway. JMO, but personal experience last year with Pertronix conversion, had rivets come loose and mucho grief. Changed back to points trigger.