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Bought this Opti quite a long time ago, used, and then ran it on my car last few years.it’s probably 15-20 yrs old. I don’t use the high voltage side, as I run LTCC setup. It’s never missed a beat, but I do have it off now while rebuilding the engine and popped it open.
One thing that has always bothered me is the stupid adjustment screw. I think it’s a terrible feature that leaves you guessing. PCM should be doing the timing adjustment and it shouldn’t be user adjustable at the Opti. MSD gives you a “this many turns out” is zero instruction. Vague. I was hoping to find a set of marks in it that would indicate zero, no such luck. Anyone know if another way to get this to zero? The LT1 doesn’t have timing marks on the balancer or pointer on the cover so I can set my timing to zero in the PCM and figure it out with a timing light.
Yellow adjust screw
red, I presume this is a spring to keep tension on the sensor against the adjuster
green, detent ball
Been doing a little more searching (including a similar thread of my own from a few years back!).
doesn’t seem to be a definitive way other than taking MSDs word on 2 turns out from bottomed is zero.
So I decided to reset it with the cap off and sure enough when I turn 2 turns out, the sensor doesn’t move because the return mechanism that pushes on the opposite side was stuck. What a bad idea this adjustable sensor is!
Having spent a considerable amount of time hunched over mine in the process of building / testing the diy-ltcc controller I've been running for the last 2-3 years, I can tell you the only sure way to know if your opti (MSD or otherwise) is indexed to zero is with a degree wheel, some coat hanger, a dial indicator and a lot of patience. Don't use a piston stop, especially if you have aftermarket valvesprings - you won't be able to tell when the piston contacts the stop and it will bend! Ask me how I know...
Anyway, there is enough lash between the distributor retaining bolts and the housing to allow for 1-3 degrees of error, so MSD's adjustable setup can be a good thing but will probably be 1-3 degrees out regardless of the position of the adjuster.
The numerous times I indexed mine, I used a special test firmware I built for my controller to light the board's LEDs so I could see exactly when the TDC / low resolution output switched. I don't think the Bailey LTCC has this functionality but you can do the same thing with a couple TTL safe test lights connected to the low and high resolution outputs.
Last edited by spfautsch; Aug 10, 2023 at 04:56 PM.
Thanks for this detailed reply. I added fresh loctite to the adjuster bolt, turned it out 2 turns from bottomed and ensured the pushback spring was applying force to the other side. I’m calling it good. Is what it is. I’ll tune spark tables with using datalogs. I too noticed the slop between the 2 upper bolts and the housing. I presumed it was because 95+ cars had different larger shank bolts that my 94 didn’t have when I converted to a vented setup. I bushed the bolt shanks to take out that slop.
Having spent a considerable amount of time hunched over mine in the process of building / testing the diy-ltcc controller I've been running for the last 2-3 years, I can tell you the only sure way to know if your opti (MSD or otherwise) is indexed to zero is with a degree wheel, some coat hanger, a dial indicator and a lot of patience. Don't use a piston stop, especially if you have aftermarket valvesprings - you won't be able to tell when the piston contacts the stop and it will bend! Ask me how I know...
Anyway, there is enough lash between the distributor retaining bolts and the housing to allow for 1-3 degrees of error, so MSD's adjustable setup can be a good thing but will probably be 1-3 degrees out regardless of the position of the adjuster.
Indexing an MSD Opti
