Valve Stem Heights

Hello all,

Brought my P79 head into a shop yesterday to have some work done. I'm having new SI valves, guides, springs, retainers installed and shave the head 0.080".

I asked my machinist if he can get the stem heights the same from exhaust/intake. He told me that they are going to be whatever height they end up at because of the new guides and valves. To get all the heights the same it would require all new seats, which he quoted as 2k+ job alone.

I've been given advice on 2 schools of thoughts here from his experience from 2 different professional builders.

1. All stem heights should be the same and there should be a zero variance on all valves in order to have the same size lash pad.

2. It is common to have different stem heights when taking it in for a valve job/guide replacement and you should see varying heights as intake and exhaust valves are different heights. As long as you have the correct size lash pads and the wipe patterns are centered, having different installed heights does not matter.

Just curious what everyone elses thoughts are on this?

Also, have any of you brought in a head to have new guides/valves installed and had success with stem heights recutting the existing seat or are new valve seats required?

Thanks!