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[Doctor Gollum]

Is 0.013mm a reasonable amount of distortion?

So, head is off the Nissan and whilst the block surface is true, the head is not. Basically it has this amount of distortion evenly in the centre of the head...

If you draw an oval around the middle two combustion chambers, the centre of the oval is dished into the head by this amount.

It is central both side to side and end to end.

The technical information states the following:

"Do not rework cylinder head (3) and crankcase (surface grinding).

The permissible production tolerances will otherwise be exceeded.

i Tightening the cylinder head bolts (4) compensates for a slight distortion of the cylinder head (3) in the longitudinal or transverse direction.

If cracks or unevenness are present,

↓

replace cylinder head (3) and crankcase.

Engine 282 in model 177 with transmission 700.42

AR27.10-P-0005MFD"

There are no obvious cracks and I take "unevenness" to mean rippling or twisting.

[Andy B]

0.013mm is about 5 tens of a thou" ..... so I'd say probably yes

[Doctor Gollum]

0.013mm is about 5 tens of a thou" ..... so I'd say probably yes

As in you would chance refitting it?

[Andy B]

0.013mm is about 5 tens of a thou" ..... so I'd say probably yes

As in you would chance refitting it?

I would ..... half a thou is pretty small 

I'd be surprised if a skimmed head was any better ..... it definitely wouldn't be if it was done on our Bridgeport at work! 

[Nick W]

As in you would chance refitting it?

I would ..... half a thou is pretty small 

Small enough that I wonder what was used to measure it.

[Andy B]

As in you would chance refitting it?

I would ..... half a thou is pretty small 

Small enough that I wonder what was used to measure it.

I did wonder myself .... fag paper under a steel rule .....  

I suspect that Al has his decimal point in the wrong place  .... 

[Doctor Gollum]

Feeler gauge and a new steel rule of suitable length

I would have used a fag paper but CBA to go to the shop to get some

[Andy B]

Feeler gauge and a new steel rule of suitable length

I would have used a fag paper but CBA to go to the shop to get some

My feeler gauges don't go that small .... 1.5 thou" is the smallest IIRC (no idea in metric )

[Doctor Gollum]

You've got me thinking now

[Andy B]

You've got me thinking now

 

[Nick W]

You've got me thinking now

I think you used the imperial gauge, and wrote it as metric. 13thou warp in a head is easily measured like you did, and is enough to cause big problems.


Your next step is to get whatever machine shop you are going to use to measure it accurately, and have them advise whether it's saveable.

[Doctor Gollum]

You've got me thinking now

 

.005"

0.13mm

 

[Doctor Gollum]

You've got me thinking now

I think you used the imperial gauge, and wrote it as metric. 13thou warp in a head is easily measured like you did, and is enough to cause big problems.


Your next step is to get whatever machine shop you are going to use to measure it accurately, and have them advise whether it's saveable.

Precisely my next step

They've asked to see the head gasket too

[Andy B]

You've got me thinking now

 

.005"

0.13mm

 

As I said then .... he's got his decimal in the wrong place. 

[Doctor Gollum]

Find out tomorrow just how knackered it actually is,. although they have reconfirmed that they can't do anything apart from clean/test it.