Question about milling heads

[rezcobra]

I have an 03 with a Ford rebuilt engine. Had a thermostat stick and got hot while on the freeway. I been losing very little fluid since then. Like half a gallon per month. Till recently anyway. Has gotten worse so looking for a new engine or heads. But a mechanic from Phoenix, AZ told me not to buy any heads that have been milled or shaven. Even .005 he said. Because it will mess with your timing he said. Any truth to that? Because i've seen heads for sale that have been milled for flatness. Just wanting to avoid any other head aches!! LOL

 

[RPM4DAZ]

The cam timing wouldn't be changed enough to even notice in most cases. When working on my 2.3l turbo stuff a while back, we went through all the geometry/trigonometry and measuring, and found that when shaved .060" to relieve some depth in the chamber we only changed cam timing by 2 degrees. And it would be towards the direction of retarding them. So, a little clean up would do little at all to the cam timing. I would be more worried about how much was shaved and the changed to compression than timing. I believe .015" will change compression by about .5:1 in a stock stroke and bore combo...

 

[Cobra03SC]

You will pick up some compression depending how much they are milled. With stock cams and pistons, there is tons of room if you milled them you wouldn't need to worry about ptv contact as long as they get installed correctly. Timing wise milling a head shouldn't have little to no effect as long as you degree them properly when installing them back. If you just installed them dot to dot, it may effect it slightly... but our cars are known to be off from the factory anyways so its a good idea to degree them.