1098 head on a 948 block

[andrew.searston]

hi eveyone
i no you have to skim the head by 40 thou to fit a 948cc block
but whats the reason of skimming the head????
is it for comrpession or something??

[bmcecosse]

60 thou - and yes - for 'compression' !

[aseriesade2]

Never mind messing about with that old engine Tom gave you, remember you have a Quiz to do next month!!!! and don't you go getting Waxoil in that engine block.

[andrew.searston]

haha very funny ade
just thinking of ideas, might just get me old head redone now that i can do them at work.
the engine tom gave me needs lots of work as theirs loads of play in the big ends ect...

[MarkyB]

Up and down play, or sideways play?

[bmcecosse]

A standard 948 head is useless - go with the 1098 head if you have one.

[andrew.searston]

sideways play???

[MarkyB]

sideways play???

The conrod moving parallel to the big and small ends.

[bmcecosse]

Moving from side to side is 'ok'. What matters - is the state of the bearings - to see that - you need to open them up. Be SURE to mark everything so you KNOW for sure where it goes back. Take pics too - lots of them!

[ampwhu]

A standard 948 head is useless - go with the 1098 head if you have one.

i am after a 12G295 head to fit on a standard 948 block. is this ok?

[bmcecosse]

Of course - one on ebay at the moment- another (not in best condition!) sold last week for ~£100. It's up to you if you think that's good value for money. A 12G940 is very much better head - and very much cheaper - and doesn't need skimming!

[ampwhu]

so a 12G295 is the 1100 head and the 12G940 is the 1275 head?

is it possible to fit the 12G940 head on a standard 948 block then? seems a strange combination to me!

[bmcecosse]

Yes - works fine - even better if you fit a 1098 camshaft into the 948 engine first!

[andrew.searston]

going back to my
which head gasket would i have to use? (1098 head on 948 block)
and it is 60 thou as i heard people say 40 thou before??

[bmcecosse]

Same head gasket - no different. I assume you are asking how much to skim off ? 60 thou will be fine - but do check if it's been skimmed already. Measure the thickness of the head - they ALL start life at 2.750" . Any less - then that's what's already been skimmed off.

[andrew.searston]

thanks
im in the process of cutting the valves on a valve cutting machine and cleaning them up
will be skimmed on monday by me

[aseriesade2]

Try not to take any fingers off or worse (think family tax credit) whilst sorting that head out or you might not be able to sign for your Provisional Licence unless they do a teeth steering auto Morris!!! Ade

[bmcecosse]

Make sure you remove all sharp edges after skimming. By that I mean - run a file round the edges of the chambers - just enough to take away the sharpness - but not enough to make a 'chamfer' . And - clean out the oil passage up to the rockers very very carefully!

[andrew.searston]

haha ade, lets hope nothing gets chopped off
and will do bmc