M90 cylinder head specs help

[Hunneman]

I recently purchased a M90 motor, I was told the is was running before the PO had dismanteled it, to change gasket and other items.
I was told that if the head has no dimples then the head is not usable as it is below the tolerance specs. But i read in the repair manual the in should be 129+-0.1mm then you add a thicker gasket.

but after measuring cylinder head I have a reading 128.69 does that mean it was resurface more than once.
so if this head is below tolernace, would a head from a M30 535i from the later E34 fit on M90, or would a M30 2.8 head fit are they interchangeable?
thanks

 

[Markos]

Paging @sfdon

 

[sfdon]

Slow down.....
Early M90 heads can come with no dimples.
Send me a pm and I will walk you through it.

 

[sfdon]

2 digit date on head please .....
Combustion side of head please....

 

[Hunneman]

the date on the head is "80"

 

[Markos]

Flip that head on it’s side and show Don the valves and water jackets.

View attachment 45823 the date on the head is "80"

 

[Hunneman]

intake & exhaust valve were replaced, rocker arms & eccentrics nad the head was machined. ihave a auto repair order that was done with PO.

 

[sfdon]

So- that’s the prime 2nd edition m90 head.

 

[sfdon]

Has the better intake ports.

 

[sfdon]

You are .03 mm above spec.

 

[sfdon]

You may want to check for level and hand stone.
Do not use any other head- you will have a steam hole

 

[sfdon]

Minimum spec is 128.6mm

 

[Hunneman]

The M90 engine is from a 1980 635 CSI euro, newer head design. so if I read this correctly, I currently have 128.69, i can have it resurfaced 1 more time not to go under 128.6mm ! which size head gasket do i use. http://www.realoem.com/bmw/enUS/showparts?id=5331-EUR-04-1980-E24-BMW-635CSi&diagId=11_0197
1) Cylinder Head Gasket Asbestos-Free 2,20MM(+0,3) 06/198711129065668
2) Cylinder Head Gasket Asbestos-Free 2,07MM(+0,3) 06/1987 11121730224

Q. does the cylinder need to be resurface?

thank you, Great info Don.

 

[sfdon]

The machine shop will want inches not metric....
Stock is 5.079 +- .004”
Minimum is 5.063 “
Yours is 5.067”

A typical head surface job is .004-.005”
Your head will end at 5.062”

The special gasket is .0118” thicker

5.062”
.0118”
5.0738”

It appears that you will end up almost perfect height with the thicker gasket after resurfacing.
Only 1 thousandths off!

Btw- no dimples on early m90 engine heads.

 

[Markos]

This thread would never have been so informative if it wasn’t for me! Asking Don for help...

 

[Hunneman]

thanks Markos ... you have been a great help!

 

[Markos]

thanks Markos ... you have been a great help!

I hope that you know that I was being facetious, but happy to "help".

 

[Hunneman]

I know