Ok, I have a 98 GM 2.2L block and all internals, with a 97 head on it.  Both motors came from S-10s.  From the research I did, with the 98 block and 97 head, I have increased the compression ratio by about 1.5-2 points, which puts me in the 10.5-11:1 range.  Pretty high for a non-modded motor.  Here's my issue.  I reused the timing gear set off of the 97 motor (because it was brand new and I'm cheap) and slapped it on the 98 crank and cam.  I have some nasty ping under load, even with premium gas and a bottle of octane booster.

 

So, by my research and calculations here's the theory and possible solution.  Any input on this would be greatly appreciated:  The 98 crank is advanced by about 0.45" compared to the 97 crank.  By using 97 gears on the 98 crank, basically, I advanced the timing by an additional 0.45" meaning now my ignition timing is advanced by about 0.90"!  I could either change the crank gear to a 98 gear, OR...rotate the crankshaft counterclockwise by about 0.5"  in order to retard the timing down to a reasonable level and eliminate the pre-ignition problem.  I have never really messed with changing the timing on a distributor-less ignition system before, and am wondering if by changing the position of the crank in regards to the cam, will I be able to retard the timing, or am I just dumb?! 

 Ok, new theory, and possibly a new solution. 

Danny R:

The '98 crank is advanced by about 0.45" compared to the '97 crank.  By using '97 gears on the '98 crank, basically, I advanced the timing by an additional 0.45" meaning now my ignition timing is advanced by about 0.90"!

  The gear doesn't make a difference when it comes to the ignition timing.  It will affect the timing between the crank and cam, but not the ignition.  Here's why.  The crank has a large wheel towards the rear of it that has notches machined into it.  Regardless of were the valve timing is set at, the sensor will ALWAYS "see" the notches and will fire when the piston is where it should be in the stroke.  Rotating the crank in either direction does not change where these marks are at.

 

Because the '97 and '98 engines had a difference by about 0.45" regarding the timing marks, the older '97 PCM is still under the impression that it is "seeing" the 97 timing marks instead of the '98's more advanced marks and the computer does not have the programming to compensate for this more advanced timing, whereas the '98 PCM is set for the crank to be that advanced already so it has the ability to retard the timing further if necessary.  At least that's the idea we came up with.  Now, if it actually works is a whole other question.  Right now, I need to disable the PASSLOCK II feature on the '98 computer in order to test this out.  Temporarily I blocked open the EGR port, installed colder plugs and am running Premium fuel, which by CA standards is only 91 octane instead of the much better 93 in WI.  Commies.  Any theories, suggestions, or forwarnings would be greatly appreciated.