A question for Opti

Since Opti is your middle, wait, first name, I hope you're the guy to ask: of the optispark replacements currently available, which one is best? Are they all interchangeable from 92-97? My engine is an early 94 y-body, if that matters.

In reply to AngryCorvair (Forum Supporter) :

I'll second this! I have a 96' roadmaster wagon in need of a replacement optispark and looking around online has me confused if there are any good options at all.

If I get anything wrong, Opti can correct.

The early Optispark was driven by a spline in the middle of the cam gear 92-94,  while the 95-97 was driven by a longer pin in the camshaft that protruded through the cam sprocket. So changing to the later design requires a different cam gear and either camshaft or longer pin at a minimum.

Used to be the Delco one was the good one, but production moved to China so it is hit or miss. I used an Ebay one on a 94 and it ran fine.  It was $73 vs $450 for the Delco one so it was worth taking the chance to me.

In reply to 81cpcamaro :

My 95 9C1 was still spline driven. Maybe an early build? There are retrofits to adapt LS style coils to the LT1. Worth looking into.

You definitely want a vented one (95 and up I believe)

My Opti was running great at 193,000. Never touched anything the 12 years I owned it

Appleseed, that is a possibility, especially with GM. I've only dealt with the F-body and Corvette ones with aluminum heads.  With either version, keep an eye on the water pump, as it usually is what kills the Optispark.

There are two types. 92-94 which are spline drive and non vented, and 95-97 which are pin drive and vented.

As mentioned earlier in this thread my last parts car was a 95 and spline drive, so I'm not a 100% sure when the break was but general consensus is 92-94 and 95-97.

I'm not sure why either drive would be important (as in, is one beneficial), pretty much everything I worked on was pin drive. Id imagine all the popular cams are available in either drive, and youve already put a cam in right? The vented part is generally considered important, and why people used to convert to the newer style opti, which required a cam change and timing cover iirc. I've seen one guy convert an early opti to vented, I'm assuming all you'd need is 2 holes, a metered air source and a vacuum source. I don't know if it's common, as I've only seen it once.

As far as brands, the important part is the optical sensor made by mitsu, which has long been discontinued so people are stockpiling them from old optis. Even I have a few and I'm not someone who worries about optis or the sensors. The Internet for the last 20 years has told everyone only an OEM is worth a damn, but I never really followed that and I never had many problems. I've ran 80 dollar eBay ones (Chandler Motorsports was an eBay seller who was on LS1tech 15 years ago), parts house specials and OEMs. I've been fine with all of them. If yours isn't bad I'd put a cap and rotor on it. If it is bad I would just go to your local parts house that has a cheap one and offers a lifetime warranty and save the receipt. Then you open it up and loctite the rotor screws (don't over tighten them though or the rotor will fracture and come apart on your first trip to 7k) and rtv the cap.

Don't forget a new opti harness. In the last decade many replacements starting coming with new harnesses, but not all of them. I've seen these misdiagnosed as bad optis. They chafe were they turn down from the top of the motor. They are cheap and available online if one doesn't come with your opti.

I didn't pay much attention to the current state of optis when I got back into LTs since I always ran parts store junk, but what I've been told is nowadays they pretty much all run a Chinese sensor (so some people are putting old mitsu sensors in otherwise new distributor). The MSD was a bust since it was new, and it's expensive. I have heard good things about Petris but not widespread use so who knows if it's real or people trying to justify the pricetag. I have seen someone mention timing being way off on the super cheap eBay ones. I figured if the quickly available and cheap parts house optis become a limiting factor for my build it's time for a 24x kit.

81cpcamaro said:

Appleseed, that is a possibility, especially with GM. I've only dealt with the F-body and Corvette ones with aluminum heads.  With either version, keep an eye on the water pump, as it usually is what kills the Optispark.

This might be overblown, I've lost more than a couple water pumps and it never killed the opti (me getting the water pump off has haha). I also pressure wash all of my LT1s. I will literally directly spray the opti with 3900 psi. I've never hurt an opti doing this.

I haven't lost one to a water pump either, the 95 TA did puke on the opti, but no issues.  The 94 engine had water in the optispark as well as other parts of the engine, probably left outside and rained on (came out of wrecked car).  That one got the Ebay opti.

thanks yall, i logged a couple of no-starts and it sets the low-res fault around the same time that Vbatt drops below 10V, so not sure if it's real. Plugs were soaking wet when i pulled them after this evening's shenanigans. I'm going to heat the garage tomorrow and give her a try with CLT and IAT in the 50s instead of the low 30s like yesterday and today. I've got FSM so I'll read up on Opti testing.  I guess pulling the water pump and crank pulley aren't the worst jobs in the world, as I've got easy access to front of engine. Mine is definitely spline drive.