I specifically asked about a 1994 shaft driven Opti, not a 93/94. I know the 93 is batch fire - that's why I did not include it. You surely know the 1994 is full sequential.

 

I think the whole issue of injector timing is blown way out of proportion, particularly with the typical application where people are knowingly pushing the injectors toward 100% DC.... they're open almost all the time... what difference will it make if the indexing of the cam to TDC is off by a degree or two.

 

Ya are right again. '94 IS sequential.Isn't the '93 also spline driven.

 

In leiu of this statement:

What is the relevance of this question?:

 

The relevance is that it affects the answer to the original question. What is true about the 95-97 dowel driven cam/TDC/Opti relationship being independant of whether you use a bushing or an offset key, it not true for a 94 (and yes, the 93 is also driven off the sprocket).

I know the answer.... I've visualized it . The 94 cam does not drive the Opti directly. The connection is from splines on the cam sprocket to the Opti. If a dowel bushing is used to move the cam, the position of the Opti, relative to TDC does not move. If you use an offset key, the relationship between the Opti and the crankshaft is altered.

On a 95-97, the dowel drives the Opti, and using a bushing or an offset key will alter the indexing of the Opti to TDC.

You also need to visualize WHY you are moving the cam. If you move the (correctly ground) cam to intentionally advance it or retard it, you have altered the relationship of TDC to the Opti. If you move the cam to CORRECT centerlines that are not ground correctly with reference to the dowel, you are "correcting" the relationship of the cam to TDC, and "correcting" the indexing of the Opti to TDC.

 

Fred,

In regards to the mechanical differences between a spline driven opti vs. a dowel driven opti and how an offset bushing effects either I'm in complete agreement with you. But can we also agree on one other point? That when we're indexing a cam to TDC, how we index the Opti in relation to that is for the purpose of spark timing accuracy and NOT for fuel timing accuracy?

 

The opti controls the injectors too.