I am rebuilding my reconditioned 3.8 head off my mk2. I am fitting higher lift, longer duration cams (Rob Beere Racing, fast road, RBCSU). Valve clearance specs are .008 inlets, .010 exhaust.
Inlets are all .008 thou apart from one which is a slightly tight .009
Exhausts are between .011 and .013.
Should I go with these gaps or strive for perfection and get new shims for the 7 that are not quite there?
Or should I run the engine for a few hundred miles and see if the valves settle in to the valve seats a little (It has new seats and valves).
If the machining work was done well, the new seats don’t settle much. After CJ rebuilt my head with new everything, a few gaps change by no more that .001 over the first 10k miles. Mine is always set dead on spec. I would hesitate to set it far out just because it “might” change. If you assemble it with Cometic gaskets, it’s not a huge chore to pull the covers to check it after it’s run for a while.
After 10-15k miles w standard cams, new valves & guides, .060" seat width my exhaust clearances closed up by .001". Intake remained as set.
I started at .008" so exhaust all still good at or around .007". Left them all alone.
Intakes still at .005-6"