46 replies to this topic

[mk3 Cooper S]

Okay how tell tell warping and over skimming and dont matter boy unleaded etc being rebuilt and will have it converted

Straight edge across the face for warping, Micrometer between the face and the top for skimming depth.

I understand about the unleaded but at £100 a unconverted sprite head for rebuild does not sound very cheap to me.

[minilee94]

He didnt say it needs rebuilding but im guna have it done 240 to get it rebuilt it already has double valve springs and 11 stud holes drilled wich is perfect for my 1380 i will be getting it has flowed too

[minilee94]

What should the standard measurement be with out skimming then so i take one a test it

[A-Cell]

Sorry Minilee94. Quick check with a straight edge, long metal rule but be sure to do it across the diagonals as well as straight across long ways and then at intervals across the face. Get your eyes down and look for gaps where the edge of the rule sits on the face. More involved check for flatness would be on a surface table with engineer's blue but thats not practical. Basically you are trying to ensure its as flat as possible.
Ideally remove the valves and look into the ports, around the valve seats for cracking. Look up ports again for signs of cracking.
As for over skimming, visually are he combustion chambers reasonably deep. If they look very shallow then it may be too hard to achieve a low enough CR for proper running on normal fuel. Also look at thickness of head through the water passages.
Get your engine tuner / head man to check it and see if the seller would take it back if it is not good when checked.
Others on here may offer you some more advice. Hope it's a good one.

[minilee94]

Okay mate thank you that helped alot cheers

[carbon]

Depth of a standard unskimmed head should be 2.75 inches (69.85mm).

Also worth checking that the brass plugs on the lower face of the head are sitting perfectly flush with the face of the head.

[minilee94]

Okay thanks can any one tell anything by picture of the bottom of it

[minilee94]

This is it

Attached Files

•  image.jpg   21.83K   16 downloads
•  image.jpg   22.23K   14 downloads
•  image.jpg   23.75K   16 downloads

[A-Cell]

It does not look over skimmed. Looks ok in the pictures. Take your time to inspect it.
One thing i noticed, if you are keeping the bypass get the tube
changed in he head for a new one, one of he later longer ones that supports the bypass hose making failure of the hose less likely. Minispares 12A2075. Good luck.
Even in standard form they are good heads, so when refurbished, mildly gas flowed and polished should perform well.

[MRA]

A steel rule is NOT a straight edge, I have seen lots of "warped" heads that in fact are well within tolerance, but because the wrong tools where used to check it the customer bought it in for machining.

Funnily enough one guy brought in his "straight" edge and I checked it out, it had a 0.016" bend in it :-(

I have also seen heads from "experts" that use a vertical spindle milling machine with the spindle out of true, this lead to a concave gasket face, it just wouldn't seal is what the customer said to me, no wonder really...

[A-Cell]

So what do you recommend he does for a quick check? Unless he takes a surface table? Or maybe a known flat head or block and some blue.
Of course a steel rule is not the most accurate, but better than no check. Help the OP out here, don't just criticise.

That's also why I suggested he asks the seller to abide by a proper check by his tuner/head modifier.

[minilee94]

He guy im getting it from is just a mini and metro breaker

What about a smallish level with that work

[minilee94]

I do mean a steel engineers rule not a plastic one lol

EDIT didnt read last post

Edited by minilee94, 11 January 2013 - 07:17 AM.

[A-Cell]

I knew you would use a steel rule. I think MRA,s point is that it still isn't that accurate, but it's a whole lot better than not checking!

[MRA]

Sorry Minilee94. Quick check with a straight edge, long metal rule but be sure to do it across the diagonals as well as straight across long ways and then at intervals across the face. Get your eyes down and look for gaps where the edge of the rule sits on the face. More involved check for flatness would be on a surface table with engineer's blue but thats not practical. Basically you are trying to ensure its as flat as possible.
Ideally remove the valves and look into the ports, around the valve seats for cracking. Look up ports again for signs of cracking.
As for over skimming, visually are he combustion chambers reasonably deep. If they look very shallow then it may be too hard to achieve a low enough CR for proper running on normal fuel. Also look at thickness of head through the water passages.
Get your engine tuner / head man to check it and see if the seller would take it back if it is not good when checked.
Others on here may offer you some more advice. Hope it's a good one.

A steel rule will tell you nothing, as they can be more bent than the head, I have been given loads of heads to skim only to find out that they are not warped, bowed or twisted in any way, and yes I do advise the customer......

The head thickness is 2.75"