A friend of mine is finishing up installation of his new 396 LT1 in his Impala SS. He removed his opti from his old engine and took it completely apart to powdercoat the base. While apart he also replaced the bearing, but he didn't note how the opti was pressed together with respect to the cam pin on the outside driving the inside.

When pressing it back together, how should the opti be degreed in relation to the cam pin? This is cricitcal because it affects the wheel in the opti as well as the rotor position. I know it has to be pretty much exactly right, or I'm going to have a boatload of fun tuning his car ...so I guess if he can't get it right I'll make him buy a new opti and not take it apart, or at least try again with another opti on the bench to compare to.

 

The following is based on notes generated from complete disassembly of new opti. Following description is with opti dowel positioning slot surface, facing handler of assembly. View is of cam dowel indexing slot at 12:00. One of 2 remaining special shaped slots is at 4:00, other is at 8:00. Slot at 4:00 is to line up with rotor.

BTW, if bearing was purchased recently, what source did friend use to purchase bearing? Sources that I was aware of, when approached, as of about a year ago, have since discontinued selling bearing. The bearings are still stocked, however, not available for sale. This [not for sale] policy went into affect, about the time 'dynaspark' opti replacement became available for sale. Coincidence?

 

Arnie, thank you for the description. We have the car running, and it's doing ok, but tuning it is a real nightmare, and I think that the opti is still not degreed properly. I guess we'll pull it back off and try again. Center of the rotor is exactly lined up with the center of the slot at 4 o'clock?

I'll ask him how he got the bearings, but I know it was done locally in MA. Whoever he's bought bearings from in the past for other projects contacted NTN (opti bearing manufacturer) directly with numbers off the original bearing and was able to order them, at a very attractive price too. He bought 3 of them, less than 2 weeks ago and gave one to me, kept the other 2 for himself, one of which is in his car. If you'd like 1 or 2, we can probably get more and mail them to you, shouldn't cost more than a couple bucks to ship something so small.

The only number on the box I have with a new bearing in front of me that could possibly be a part number is SX03A13LLUACS25#01 and that same number minus the #01 part is on the bearing itself. I do see that as a strange "coincidence" and I also see the dynaspark as not worth it at all, I'd rather run a stock opti base with an LTCC setup. Being able to replace the bearing in that base if need be is a nice alternative to buying a complete opti knowing you're not going to use half of it.

 

Did you ever figure how the opti hub and rotor are to lined up with respect to each other? I pulled mine apart and did mark it before hand. This is for a vented opti.

Kris

 

So, based on what you discovered, is the info in my post, accurate or is it inaccurate?

 

Sorry...should have read didn't mark it before hand. I have no idea how it should be degreed this was the only post I could find regarding the subject after numerous searches. Looked like Mike454SS didn't have any luck just wanted to make sure the info was accurate.

Kris

 

OK followed the instructions as above...lined up the rotor with the 4 o'clock special slot. Did another search in regard to the dowel pin on the cam position in relation to a cylinder. Found that with the dowel at the 3 o'clock position #1 should be at TDC. Well with that info the indexed special slot is pointing at the 6 mark and the rotor is pointing at the #3 cyl distributor point. Shouldn't it be on the #1 cyl distributor point?

Kris

 

Yes, unquestionably! With #1 piston at TDC, the rotor, with it's wide terminal, can be directly over the #1 plug terminal of cap.

 

Is the info on the cam dowel correct?

Cam dowel at the 3 o'clock position cylinder #1 would be at TDC...if so something isn't right.

What are the markings 1 & 6 on the back of the opti for?

Any help in shedding light on the subject would be appreciated.

Kris

 

Did another search, huh? Are you sure of THAT info? Another ?. Are you REALLY sure of that info?

Is the info on the cam dowel correct?

Guess it depends on what info you wanna believe, doesn't it?
I stand by the info I presented. I posted ACCURATE info. Believe what you want.

 

I didn’t want to chance messing something else up so I bought another opti. After disassembly I found that with the special indexed slot at the 12 o’clock position and facing the back of the opti where it is stamped with a 1 and a 6 (180 deg apart). The 4 o’clock special non-indexed slot is inline with the rotor index hole (received by the plastic tab on the bottom of the rotor) which is approx. 45 deg from being inline with the rotor.

Edit: Just to clarify so its not out 180 degrees. Looking down at the rotor the rotor index would be on top of the 4 o’clock special non-indexed slot.

Kris

 

With a vented opti camshaft dowel located at 9:00, when #1 piston is at TDC, your post has merit, and is worth noting. I notified Mike that I unfortunately, no longer have confidence, in the accuracy of the info, contained in my post. This is disheartening, for I pride myself in posting accurate info.

 

That makes sense about the dowel at 9:00 = cyl #1 TDC because with the indexed slot inline with the 1 on the back of the opti and the rotor is pointing at the distributor cap's #1 cyl point.

Kris

 

I tried to help Dave set it up right, but then I realized, the opti has to be assembled with such fine precision that it's damn near impossible to do it perfectly, even if you did mark it (unless you could somehow put a keyway into it). As a result I decided that I refuse to tune his car until he puts a new opti on it, so his new 396 LT1 is currently waiting for a new opti, and a new tranny too.

As for the location of the cam pin, when the pin is at 9 the engine is at #1 TDC, you assemble it with the engine at #6 TDC (dots on the timing set) which is the cam pin at 3.

 

I'm the Dave that Mike is talking about. When you line up the cam-pin hole on the opti with the #1 on the back, it is in the position to fire the #1 cylinder, I marked the opti where the #1 plug wire touches the rotor and lined it up and that is how I got my car running. But as Mike has sait if you are 1* off then your injectors will be firing at the wrong time which is why I'm in the process of buying a new opti.