Secondhand/recon head questions ???

Post Mon Oct 24, 2005 9:28 pm

Do I need to grease the cam with cam lube ???

How do I find out if the head is skimmed?

Post Tue Oct 25, 2005 12:52 am

I think using cam lube is considered best practice, although I never bothered with mine. When it was all back together, I left the rocker cover off and tipped the oil into the engine all over the cam and followers, put the cover back on, then started it up.
I'm not sure how you would tell if it's been skimmed unless you measured it and compared it with the factory thickness. I think there are visible machine lines even on the original ones.

Post Tue Oct 25, 2005 7:13 pm

124.7mm is the minimum height of the head, if my notes are correct.
I assemble cams with hypoid (diff) oil.

Post Tue Oct 25, 2005 7:26 pm

What happens when u put a standard head gasket to a skimmed head?

- more power gain

- or values clashing

Post Tue Oct 25, 2005 7:43 pm

e30bb wrote:What happens when u put a standard head gasket to a skimmed head?
- more power gain
- or values clashing

I bought a reconned 325 head once (with the emphasis on the "conned" bit), that had been skimmed below 124.7mm.
Was OK cold, but as it warmed up a metallic tapping started, as the pistons began to just kiss the combustion chamber. When I returned it to whence it came, they ground out the chambers a bit. Was OK when refitted, so there couldn't have been any valve contact.

Post Tue Oct 25, 2005 8:05 pm

looks like i need to get the rule out.

Where do u measure the head?

Post Tue Oct 25, 2005 8:07 pm

e30bb wrote:l

Where do u measure the head?

Bottom face to top face.

Post Sun Oct 30, 2005 2:02 pm

Just under 126mm. Do I need a thicker gasket?

Post Sun Oct 30, 2005 2:24 pm

126mm is more than 124.7mm. What makes you think you need a thicker gasket?

Post Sun Oct 30, 2005 2:44 pm

Whats the orginal height?

Post Sun Oct 30, 2005 2:49 pm

OK, cool.

Thanks guys.

Found something in Bentley Manual:

6 cyl new 125.1mm after maching 124.7mm
4 cyl new 129.0mm after maching 128.6mm

Post Thu Nov 03, 2005 6:37 pm

There is an easier way. You can find a small hole somewhere on the bottom surface. If the head is brand new it should be 0.5mm deep. If there isn't any - the head was skimmed 0.5mm or more. Better put a +0.3mm gasket then.

Post Thu Nov 03, 2005 8:07 pm

cool!