Camber for 285/30/18 +47-50 offset
 

Could you run no camber or what is the minimal with that offset?

How much camber is required to clear the front fender lip with that fitment depends on how much you pull out your front fenders when you roll the lip under.

The rear may or may not require a fender lip roll (depending on actual tire width- they vary).

Your camber should match your intended use.

At the bare minimum here are the stock alignment specs. The middle number is the number the factory aimed for and on the far Right is the allowable range.

0 camber is not a spec even on stock alignment though it is within the allowable range in front.

Stock alignment specs-

Application Preferred Range
RX7
Camber (1)
Front ....................... 0.10 ................ -0.65 To 0.85
Rear ........................ -1.22 ............... -1.97 To 0.47
Caster (1) .................. 6.08 ................. 5.08 To 7.08
Toe-In (2)
Front ................... 0.04 (1.0) .. -0.07 To 0.15 (-2.0 To 4.0)
Rear .................... 0.08 (2.0) .. -0.03 To 0.19 (-1.0 To 5.0)
Toe-In (1)
Front ....................... 0.10 ................ -0.17 To 0.37
Rear ........................ 0.17 ................ -0.10 To 0.43
Toe-Out On Turns (1)
Inner ........................ 36 ......................... .....
Outer ........................ 32 ......................... .....
Steering Axis
Inclination (SAI) (1) ....... 13.92 ........................ .....
(1) - Measurement in degrees.
(2) - Measurement in inches (mm).

Here are some recommended FD alignment specs from the old Pettit website-

https://cimg8.ibsrv.net/gimg/www.rx7...84bab67fb3.jpg

I did a moderate pull with my front fender roll to fit my 18x11 +45 with 295/30-18.

I run the max camber I can get in front (-2.4) and minimum rear camber with stock components for auto-x (could use more front).

If I were to run the fitment you outline above on my car I could take out at least 1 degree if for some reason I wanted to.

So with this front fender I could run -1.4 camber on the fitment you mention.
https://www.rx7club.com/attachments/...vr-r1-gate-jpg

https://www.rx7club.com/attachments/...vr-r1-gate-jpg