Which bin to start with

[RS Morgan]

Should I be starting off with ACSU bin for 700r4 trans? or ACSR bin for turbo 350 trans? I have the turbo 350 in my 87 blazer. It came originally with a 700r4 so common sense tells me to go start with the ACSR bin. I downloaded both and compared them and noticed the timing tables are only slightly different, why is that so? Gear ratio is 4.56 with 35 inch tires with vortec heads if that would matter in which choice of bin file to start off with.

[dave w]

In my humble opinion (IMHO), the Vortec heads require a custom timing table. IMHO, the stock TBI timing table is a HORRIBLE timing table for Vortec heads.

Maybe information in this thread will helpful: http://www.gearhead-efi.com/Fuel-Injection/showthread.php?1233-1998-Vortec-Timing-Table-(Black-Box-Computer)-Open-Closed-Throttle-ONLY

The stock Vortec timing is not optimal, its not HORRIBLE either.:thumbsup:

Typically, manual transmission files have all ZERO's in the TCC Tables, perhaps a Turbo 350 chip would benefit with all ZERO's in the TCC Tables.

dave w

[RS Morgan]

In my humble opinion (IMHO), the Vortec heads require a custom timing table. IMHO, the stock TBI timing table is a HORRIBLE timing table for Vortec heads.

Maybe information in this thread will helpful: http://www.gearhead-efi.com/Fuel-Injection/showthread.php?1233-1998-Vortec-Timing-Table-(Black-Box-Computer)-Open-Closed-Throttle-ONLY

The stock Vortec timing is not optimal, its not HORRIBLE either.:thumbsup:

Typically, manual transmission files have all ZERO's in the TCC Tables, perhaps a Turbo 350 chip would benefit with all ZERO's in the TCC Tables.

dave w

Sounds like either bin i start with I would have to adjust timing tables a good bit. Thanks for the info and link. Was hoping I could get a decent start from an existing bin. Still trying to overcome the learning curve with tuning tbi.

[PlayingWithTBI]

Sounds like either bin i start with I would have to adjust timing tables a good bit. Thanks for the info and link. Was hoping I could get a decent start from an existing bin. Still trying to overcome the learning curve with tuning tbi.

Here's a link to a spreadsheet (bottom of post 3) developed by @84Elky on thirdgen.org, he also posted it here but I don't readily have that link. I used it on my 5.7L with aluminum heads and a bump stick (among other stuff). It helped quite a bit along with data logging and minor adjustments to reduce KCs. HTH

https://www.thirdgen.org/forums/diy-prom/761049-spark-advance-table-example.html#post6301288