Sanity Check Cadillac 500 Tune

I've been working on my 1995 Cadillac powered Chevy for a while and got most of the bugs worked out. I was hoping to get some feedback to see if I've made in egregious errors or if I'm on the right track. I've attached the bin and a couple log files.
The specs are 1976 Cadillac 500, 1988 454 TBI with the red/black injectors. I am using the factory 454 Quadrajet adapter. I am using the 500's distributor with a lockout set to 12 degrees advance. I have converted it with a module from a 4.9 and a 368 Cadillac pick-up coil. I am using a dash/ecm 3 pin combo temp sensor located next to the thermostat. All the other sensors are from my old 350. Trans is a 1995 4L80E 350 stall rebuilt with dual feed and couple mild upgrades.

My two bits, switch to 7427 ecm, use $OE bin most closley associated with the trans and tune engine from there. You will have to make adjustment for the injectors you are using and motor requirement but you will have to do that no matter what ecm you use.Re read your post and very possible you are already using pcm from your 95.

I am using an 8625 with $0E based on BHDF already, based on your recommendation. It works pretty well.

anymore pictures? sounds like a cool project. 350 knock sensor should be ok as it has similar bore to the 500?

Here's a few more. I am using a 350 knock sensor and it works fine, as some of my early tunes indicated. :innocent2:

I wonder if the distributor (without vacuum advance) from a 1984 Cadillac Fleetwood 368 (6.0 Liter) might be a better distributor option? What I don't know is if the 1984 Cadillac Fleetwood 368 (6.0 Liter) distributor (without vacuum advance) will actually fit in the 1976 Cadillac 500 engine. A factory fitting HEI distributor with a 7 pin module will provide a solid foundation for computer controlled timing.

A few years ago, I had shifting issues with a 4L80E controlled by an '8625 PCM. As a what if troubleshooting step I installed a '7427 (because I didn't have another '8625 to troubleshoot with) and the shifting issues were resolved. I'm still puzzled as to why the '7427 fixed the 4L80E shifting issues. The '8625 that had issues with shifting the 4L80E, is working flawlessly in another vehicle controlling a 4L60E. The '8625 was not original equipment for a 4L80E.

Knock sensors are "Tuned" to engine cylinder bore diameter. The Cadillac 500 has a 4.300" bore diameter, so perhaps the Chevy 454 knock sensor with the 4.250" bore would be a closer match for a knock sensor?

Seemingly I had better tuning results, using the newer 454 28 PSI regulator & 28 PSI injectors with a '7427. If it's possible, using stock factory injector parameters will provide a solid foundation for injector control. Was the '8625 used with the 13 PSI regulator & 13 PSI injectors on the 454 in 1993?

Most times using a combination of TBI parts that are closest to the original factory specification can prevent headaches?

dave w

My distributor at this point is functionally identical to a 368 distributor. I could use a 368 distributor if I wanted to find one. I have full computer controlled timing. As far as the knock sensors these older sensor are very wideband in their response and the part numbers were used on several engines.
My truck runs and drives pretty well. I have no shifting issues. I was just hoping for someone to peek at my datalogs and tell me if they see anything weird.

Being as you are using $OE bdhf which has been my big block choice for some time you might want to look into. Years ago I experimented with moving the static advance around and adjusting the advance table accordingly . Even though the total advance should have been the same, putting it to 3 degrees as it came stock ran better. I can't give you an exact reason or example but it just ran better.

Try using the WBO2 spreadsheet I posted here to crunch the data log: http://www.gearhead-efi.com/Fuel-Inj...g)-Spreadsheet

The data log will need to be exported into a .csv file, then copy / paste the exported .csv into the spreadsheet.

Without WBO2 data, the spreadsheet will still show spark advance.

With WBO2 data, the spreadsheet is a good tool to tune with.

dave w

I have been using that spreadsheet, it a great tool. I use an AEM wideband fed in through the EGR position wire.

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Originally Posted by mihela

As far as the knock sensors these older sensor are very wideband in their response and the part numbers were used on several engines.
My truck runs and drives pretty well. I have no shifting issues. I was just hoping for someone to peek at my datalogs and tell me if they see anything weird.

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I dont know if I agree with this. I would think using a knock sensor for a smaller bored engine on a larger bored engine will make it less sensitive. Perhaps you're not showing knock when knock is present. I would run the 454 sensor myself and see if the results are different.

Both sensors are the same! AC Delco 21392, GM 10456549. I checked that before I quit working at Chevy, and RockAuto is the same.

good to know, thanks for checking