Will a 1.4mm tip be okay for both spraying primer, sealer, and basecoat clearcoat. Or do I need different tips. And also I only have one spray gun which is not gravity feed. Can I use it to spray everything or do I need different guns. And lastly, I have 33gal. compressor 8.6/6.7 @ 40/90 psi. Can I use an HVLP gravity fed gun with that kind of compressor or will I run out of air because the compressor is only 33 gallon. Thank you

I suggest getting an inexpensive gun for primer. Because primer will gum up your gun, and ruin your basecoats and clearcoats. For primers you should use 1.5mm-2.0mm, especially when spraying high build primers.

I also suggest having a variety of tips, 1.2mm, 1.3mm, 1.4mm for your base/clear gun. A wide arsenal helps out.

I answered your compressor question in the other post.