Hi All,

I am looking for a copy of the factory ignition map programmed into the factory ECM used on a MAP-based L98(aluminum head) + 700R4.

I have a 1989 L98 + 700R4 in my 1966 ChevyII. I converted the MAF-based L98 to MegaSquirt(MAP/speed-density) and have it running reasonably well.

I am looking for a GM-supplied ignition map aka spark table so I will have a known good baseline from which to start tuning. I need to reproduce the ignition behavior of the stock 1227165 ECM.

Please let me know if you have any information on where I might be able to find this file. Also, it would be helpful to know the file name I'm looking for.

Thanks in advance.
Ron

 

Look (goog) for the ANHT $8D BIN. That is a '90 y-body 700R4 calibration.

RBob.

 

Keep in mind that the factory GM timing map is handicapped for emissions reasons and that your 1966 is nowhere near as aerodynamic as a C4 Corvette. Also keep in mind most of those C4 cars ran ring and pinons as steep as 2.59:1. With the common gearing in those older cars you will be turning more RPM and pushing more load. The timing map used for a Corvette may be totally unsuitable for your car. The ECM you need to use is the 7730 as an underhood derivative 727 was used in the 90-91 speed density "MAP" aluminum head corvettes.

 

If its an iron head fbody L98 do not use the vette tables.

I think a search for AUJP should do it. Any 91-92 L98 fbody bin should be a good start

 

Hi RBob -

Thank-you for the reference / info. I've loaded it into my MegaSquirt DIYPNP D56 system. The data logs don't show any signs of detonation and performance is noticeably better.

specs for my 1966 ChevyII coupe: rear axle gears = 3.55, rear tire = 255-60R15, vehicle weight (no driver, half tank gas, no spare tire) = 2940 lbs, aluminum headed unmodified L98 + 700R4.

Thanks again for your help; it is much appreciated.

Ron R

 

Hi Fast355 , Orr89RocZ -

Thx for the info and recommendations. I am trying out RBob's recommendation and testing to date indicates that it will work for me.

Ron