I was working with 63 Bomb OHC on a Base Timing Table project and was attempting to duplicate the settings from the factory manual. While I could get it close, I found that with some slight modifications it was a little easier for me to use. I take no credit for the calculations performed in the Excel spreadsheet, they work quite well as originally designed.

I changed the following:

Enter the initial timing (equivalent of engine at idle with no vacuum).

Enter the total mechanical advance of the distributor.

A new value of mechanical plus initial is now displayed and is the WOT value.

The vacuum advance portion is unchanged. Note that in the GM manual that we were using, it provided the total vacuum advance and it also provided the start vacuum and the all-in vacuum values. Using the calculator the vacuum advance starts at five inches of vacuum which converts to 84 kPa, for example.

The table axes did not match what we wanted to use for MAP or RPM in the Config File. You can now enter these values to match your Config File. The axes spacing is uniform, but if you manually adjust values after setting the range the calculations will still be correct.

The Excel spreadsheet currently only supports N/A applications. It will add timing for increasing vacuum and has no provision to retard on boost. I believe there are some tools on the web that can do this.

I also added two columns for psi and inHg next to the MAP kPa axis. These are approximate values for relative comparisons. Here are the revised parameter entries:

Initial Timing 10°

Mechanical Advance

Total Mechanical 22°

Mech plus Init 32° (Calculated, do not enter.)

Start RPM 1000

Peak RPM 3000

Vacuum Advance

Total Desired 10°

MAP Start 84

MAP End 52

Vacuum Conversion

Vac inHg 5

MAP kPa 84

Table MAX kPa 105

Table MIN kPa 20

Table MIN RPM 500

Table MAX RPM 5500

To see how the table works, enter zero for the total desired vacuum. You'll see that advance will start at 1000, for example, and it will be all-in at 3000 if you use the values above. Next, enter zero for initial and mechanical and you'll see the vacuum advance contribution. Changing the start and end MAP values will raise, lower, widen, or narrow the vacuum advance range. A wild cam with low idle vacuum may require a higher initial timing value and/or a higher start MAP value, for example.

__Revised EFI Timing Table Generator.zip__I changed the following:

Enter the initial timing (equivalent of engine at idle with no vacuum).

Enter the total mechanical advance of the distributor.

A new value of mechanical plus initial is now displayed and is the WOT value.

The vacuum advance portion is unchanged. Note that in the GM manual that we were using, it provided the total vacuum advance and it also provided the start vacuum and the all-in vacuum values. Using the calculator the vacuum advance starts at five inches of vacuum which converts to 84 kPa, for example.

The table axes did not match what we wanted to use for MAP or RPM in the Config File. You can now enter these values to match your Config File. The axes spacing is uniform, but if you manually adjust values after setting the range the calculations will still be correct.

The Excel spreadsheet currently only supports N/A applications. It will add timing for increasing vacuum and has no provision to retard on boost. I believe there are some tools on the web that can do this.

I also added two columns for psi and inHg next to the MAP kPa axis. These are approximate values for relative comparisons. Here are the revised parameter entries:

Initial Timing 10°

Mechanical Advance

Total Mechanical 22°

Mech plus Init 32° (Calculated, do not enter.)

Start RPM 1000

Peak RPM 3000

Vacuum Advance

Total Desired 10°

MAP Start 84

MAP End 52

Vacuum Conversion

Vac inHg 5

MAP kPa 84

Table MAX kPa 105

Table MIN kPa 20

Table MIN RPM 500

Table MAX RPM 5500

To see how the table works, enter zero for the total desired vacuum. You'll see that advance will start at 1000, for example, and it will be all-in at 3000 if you use the values above. Next, enter zero for initial and mechanical and you'll see the vacuum advance contribution. Changing the start and end MAP values will raise, lower, widen, or narrow the vacuum advance range. A wild cam with low idle vacuum may require a higher initial timing value and/or a higher start MAP value, for example.

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