I'm in the process of getting my motor together, and have a few questions. My cam was at a 105 icl when he put the cam in the shortblock. It needs to be at 108 icl. He then moved the crank gear and got the cam at a 109 icl. I was told that this would throw the opti timing off and that the car wouldn't run right. I don't understand how this throws the timing off, and neither does the guy assembling my motor. I have searched, but haven't found anything on this situation. Any info is greatly appreciated. I bought some off set cam bushings from Jegs to put in if we have to.

 

It shouldn't? Im trying to think of how it could, but from my understanding of how the opti works, it is basically exactly the same as doing it with the cam.

 

If you alter the relationship of the timing of the cam to the crank, it throws off the opti timing. The opti gets it's cam and crank position info from the cam and it only knows what it is supposed to be if it is oriented like stock to the crank. You would have to compensate by reprogramming timing in the computer.

 

Consider getting an MSD Opti.... I believe that is why they added the +/-5deg timing adjustment.... to allow the Opti timing to be corrected relative to crank TDC when the cam position has been retarded or advanced. As Shoebox pointed out, altering the position of the cam relative to the crank, throws the ignition timing "off" since the PCM is assuming the standard relationship of the cam/opti to the crank position.

 

>does the MSD optispark suffer from any of the down falls an the stock on does? or was it a night and day improvement?

 

This has been debated to hell, but the truth is I believe most people who are putting cams in have them in at the wrong centerline due to timing chain variations, crank key notch variations, and cam grind variations.. most aren't checking their ICL, throw them in dot to dot, and call it a day. This isn't to say there aren't plenty running well with this method.. but those who check seem to find the cams off a few *

During both of my last cam installs the cams came up in a similar situation to yours.

That being said, quite a few of us now have used either a cam bushing or an offset crank key with success. I also moved mine 2* to get it to the correct ICL and have not had any tuning issues with my car *and* the car runs great.

I even asked Bryan at pcmforless and here was his response:

 

What is a cam bushing and how does it work?

I'm trying to resolve a +6* issue.
I've got a 93, so I'm kinda strapped on timing set options.

 

I bought mine from Jegs. The cam is within .75*. worked out great.