Well just thought that I would post my luck obtaining the timing table for a 1226455. I was able to read the chip as a 2732A by bending pin 18 up and supplying it with 5VDC from pin 24. I then seperated the full 4K bin into 4 1KB sections, the addressing started at 0C00 on my prom. I was then able to use the table locater in TunerproRT to find the timing table (used the 8079 hack to find its size). Here is the end result, the timing table for a 1983 G20Van 305 4 bbl. Why might you ask, I just converted one of the 190 HP LE9 305s (9.5:1 compression, 14022601 heads, 929 350 camshaft) to TBI and the factory TBI table does not work for that application. You can easily see how much more aggressive the timing table on the factory 305 is when running 14022601 heads. This was perhaps the biggest twist. This is what I am running for my 305 Vortec TPI in MY 1983 G20 Van. This table was created entirely by me to fit the engine. Strikingly similar.

That's interesting......wonder if it will work for an L69 bin.

That is the same ECM# as some of the early L69s (83-84 ESC (van had an ESC setup). As long as it uses the 82S181 1Kb prom (no UV window or EEProm) meaning 1 time write, you can use this method to retrieve it. The same Prom was used in the Crossfire cars as well. I have a timing table for a L69 Monte Carlo SS, if you are interested.

Cool.........

Thanks.......DM

This is the 1985 Monte Carlo SS L69 spark table.

Thanks Chris. One question, is the table what you get or are there more adders?

There are a couple of adder tables, but it is for Coolant Temperature and TCC Locked retard (which was all 0s on the Van).

Thanks......it does not look like the L69 runs allot of timing in that case. Or is this another case of a conservative GM tune?

I am sure both tunes are very conservative. It is also likely that the Car engine needed the timing retarded more at cruise to help keep the catalytic converter hotter to meet the tougher emissions demands. There were BIG emissions requirements differences between a 1983 LD Truck and a 1985 passenger car.

very cool.
Are you going to do the entire bin?
Any chance you are going to share your ecu file?
Any chance of doing the crossfire bins?
btw the crossfire works great on a 305 van!

I haven't really put much into reversing the whole thing. Probably wouldn't be too hard to disassemble it and comment it as little as the prom contains, but I really just don't have the time to mess with something I will no longer be using. I am going TBI so the CCC Q-Jet is hitting the shelf in the garage.

Once again with the crossfire, I don't own one and really haven't even found a .bin to look at.

If I ever make an ECU file it will be public.

Have you run a crossfire on a 305 van? I've seen a FACTORY crossfire fuel injected 350 fullsize van. It had RPO L83 on the factory build sheet.

I just found a few more CCC Q-Jet proms and the Junkyards gave them to me. CPN came from a 1983 Grand Prix LG4 and CDB which was a 1985 Buick with a LV2 307 Oldsmobile. I have only been able to fully locate the LG4 timing table so far. I think I have the Oldsmobile table, but it looks very strange.

Without doing a disassembly, how are you figuring the "Main SPark Bias" value? Just curious.

I wish I had time to fully dissasemble the bins, but its an assumption made off of the $40 hack (8079 CCC Q-Jet ECM). Also 16-20* of timing at idle is a very normal idle timing for a small block, regardless of the heads that are on it.