cylinder heads - reface limit

[Seight-V8]

hiya all,

The rover v8 manual for the 4.6 engine, states that the cylinder head reface limit is 0.50mm...

There is a measurement of 22.94mm from the face to a step on one end of the head.....so the minimum limit would be 22.44mm..

So what if the dimension is more like 22.15mm....hows this going to effect the valve to piston clearances?????

Or the compression ratios.....although the ports must have been modded back to be equal...as they are marked as 29cc.

Will i need adjustable push rods to get the clearances back????

cheers

scott

[CastleMGBV8]

Scott,

What exactly are you trying to achieve, if just raisng compression, using tin gaskets for a 3.9 will have the same effect tin gasket is 18 thou comp is 46 thou.

As for the valve gear then it's a bit of a can of worms, and depends on what cam your using and what lifters, The existing valve gear geometry is far from perfect.

Whats the spec of the engine especially the cam and what is it to be used for?

Kevin.

[Seight-V8]

hiya,

not trying the achieving anything but get my engine back together....but things are outside my control.

Heads have been machine too far past the reface limit...and it worries me about what will happen internally.

My next post will explain all...as my blood is boiling about these.

scott

[mgbv8]

Scott!
Can you not overcome this problem by using more shims on the rocker pedestals??

You know the lift you have from the cam. You can calculate the available lift on the valves if you use some check springs so you can measure what actual gap is between the valve guide and the bottom of the spring cap.
Factor in the rocker ratio and you will know if the cam is going to make the caps hit the guides.
This will rule out one possible fouling problem.

[JC.]

Comp gaskets are thicker than the steel type.
Can't recall if the 4.6 used these or not as standard?

If the answer is no, then you'll gain a little more clearance from the comp gasket.