4G63 head rebuild

Hello,

so today i decided to start stripping the block and head for forging (wanting to make around 800hp).

I got all the parts to build the head but i am stuck with a few question.

It will have GSC intake & exhaust valves, Kiggly HP beehive kit, and GSC S2 cams. Basically a normal setup.

So here come my questions:

- Do you need to angle cut the seats for those valves or is lapping them enough?

- How can i check if my valve guides need replacing? Can't seem to find a spec of runout anywhere. (I assume you check this with a dial gauge wiggling the valves?)

Any advice will be appriciated.

Kind regards,

B.

For that power level it would be foolish, IMO, to take any short-cuts.

Normally one would just, as you say, check the play in the guide and if it's "good enough" just bebuild the head.

However, for the small investment, a new set of guides would be a smart move and it may offer a chance to use a better material and optimised clearance - there are guys here with a lot of experience on these engines who can advise on both.

With new valves it's always good practice to re-cut the seats, especially if a different manufacturer is used, as the seat position may be slightly different, always if their diameter is different, and it give a 'virgin' seat - when replacing guides it's normally an essential, anyway, as the replacement guide(s) may be slightly off-centre from the originals.

There is one important thing you need to remember - you definitely need ARP head studs for that power level. Applying more torque can change valve position at the seat causing leaks. Something to bear in mind. Evo 9 heads are prone to warping because of that....