9 replies to this topic

[Steve-O 2014]

I have a 295 head that's been skimmed down to about 22/23cc but would like a light skim to remove scratches from it. What areas need checked to see if it will take another skim?

It measures 2.67" does that mean it's has a 80 thou skim?

Thanks

[Cooperman]

There is an oil feed hole which goes from one of the rocker pillar mounting places towards the head face. 

Measure the depth of this and subtract it from the head thickness. That gives a figure for the remaining metal between base of the hole and the head face. The head can be further skimmed until not less than 0.050" remains. It is unwise to go below this figure.

[blacktulip]

Also isn't 22/23cc chambers getting on the high cr side unless you are using low compression pistons.

[Steve-O 2014]

Pistons fitted are 6cc dished +40 thou

But there's some light scratches on the face in places that I can feel with my nail so thought would be beat to skim ?

[Steve-O 2014]

Another question do I need to remove the valves for a head skim?

[cal844]

Another question do I need to remove the valves for a head skim?

Yes, the head needs to be fully stripped

[Cooperman]

Another question do I need to remove the valves for a head skim?

Yes, strip the head completely so that swarf doesn't get into the valve guides, under the springs, etc.

Edited by Cooperman, 16 April 2017 - 05:25 PM.

[carbon]

Pistons fitted are 6cc dished +40 thou

But there's some light scratches on the face in places that I can feel with my nail so thought would be beat to skim ?

Depending on where the scratches are and how deep they are you may not need to skim the head.

 

Most critical area is where the head gasket seals around the edge of the bores, particularly between cylinders.

 

Also check the condition of the block face, this is just as important as the head. Worth checking both carefully with straight edge for any signs of distortion, ideally should all be within a couple of thou.

[Steve-O 2014]

Looks like i have 1.5mm left which is 0.0591 inch but need to measure again with my digital gauge

[tiger99]

A quick lick with a surface grinder will only take off a couple of thou, which will make very little difference to anything except the scratches. Just ask the machine shop for that, and no more, and you should be ok.