valve springs

If you look up the specs for that part number spring in the valve spring section of the TF website, you’ll find the specs won’t match what you posted(the info on the paperwork with the heads).

TF buys that spring from PAC. It’s a number 1294.
The specs in the PAC catalog match what is on the TF site in the spring specs.
The ones I have tested myself match the PAC specs.
It’s a pretty stout spring for a FT cam.
Careful break in will be required.

4EB015E3-D806-4B71-8218-3428FDF66010.png

So, the rate is 427lbs/in based on the chart...... which would put them at 154lbs at 1.950, not 138.
Starting at 154, and adding .600 lift would put them at: (427 x .600 = 256, +154 = 410 open).

The PAC catalog shows [email protected] and [email protected] for the 1294.