Head surfacing?

[RKTMech]

Lets try one more time, How much have you had surfaced off of LLY heads, What would be Max! knowing that .0039 is max factory and that the valves are about .032 avg below the surface. This is for a hail marry stock motor build......... Lets have it boys I know some crazy azz sht has been tried lets hear it :thumb:

Thanks Robert

 

[Trippin]

You can mill quite a bit. The main problem your facing is piston to valve clearance. It is approx .045 from the factory. So anything you mill from the head tightens up the clearance.

The factory valve recession is .025 Intake and .035 Exhaust. So anything more than around .005 and I would start thinking about doing a valve job to recess the valves into the head.

The next problem you face with milling is the risk of the intake bridge not fitting as milling the decks lowers the head on the block and effectively tightens up the V that the bridge fits into.

A good rule of thumb once you exceed .010 from the deck is to mill the same amount from the intake side of the head.

Hope this helps,

Guy

Ps,

Before you ask, a .010 thicker head gasket will cure the P to V issue but will also drastically lower the compression.

 

[RKTMech]

Hey thanks Guy, I was hoping you would happen by..... So how drastic would it be going from the B to a C grade gasket to compensate for the milling seeing how thats about .020??? Would you notice a performance difference or maybe smoke on a stock build?
Thank you for your time and insite

 

[Trippin]

B to C is only about .002

 

[RKTMech]

That was an ooops, shouldnt be reading and trying to think before bed! Thanks for the correction Guy, What about the D grade are they just another .002? Are there more than the factory selection of head gaskets available for thickness?

 

[RKTMech]

Thanks for all the info Guy, we have set a plan of action and will see how it goes have a great holiday.

Thanks again Robert

 

[dartman92]

I got my heads back from being surfaced and my valve recession is .020. I wonder if that is to tight and I should get the valves sunk.