Classic cars forum & vehicle restoration.

[1935Hillman]

Hi everyone again,

I have a much sought after aluminium cylinder head for the s/v Hillman but it has an obvious fault in that it appears that at some stage something went wrong in just one of the bores and the head is pitted quite seriously in that particular section (looks like a hard cheese surface that has been pecked by a small bird)
Does anyone have any ideas as to a likely course of action for me to improve it as otherwise it is in excellent condition.

Many thanks,

Tim

[peter scott]

Hi Tim,

I very much doubt that it will cause you any problem. If I were you I'd just use it as is. The chances are that the surface has just been disturbed and you wont notice any change on the compression of the damaged cylinder. (i.e. low spots will sit beside corresponding high spots.)

You don't really want to try and smooth it out as that would result in a loss of compression ratio in that cylinder due to the lost material which would force you to do the same in the others. Then you would have an overall comp. ratio reduction which might warrant a skim of the mating face. On an old alloy head you should avoid skimming if possible because previous skims will already have reduced the wall thickness.

HTH

Peter
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http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[1935Hillman]

Hi Peter,
Yes, what you say makes perfect sense. Its not a F1 car so you are probably right.
Thanks very much
Tim

[Phil - Nottingham]

I have run many cars with this sort of damage for years - its mostly caused by a broken pistion ring or by the careless dropping of a screw/nut from carb or elsewhere into manifold
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Rover P2
Rover P4
Rover P5 & P5B
Land Rover S2 & S3
Morris Mini Traveller Mk2

[baconsdozen]

I remeber taking a head off an old car and finding the same thing,we put it all back together,and it carried on running well.A year or so later we fitted a new silence as the old one was rotten.It rattled when shaken and out of curiosity I cut it open.Inside was the remains of the top of a spark plug battered and burnt.I suppose it had fallen off during a plug change and been left inside.
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Thirty years selling imperial hand tools for old machinery(Now happily retired).

[bluto]

One warning

Please be sure you clean the rough edges off the combustion chamber. Sharp edges cause further detanation damege

Next it ts a good idea to install the plugs and check the threads on the plug or in the head are nt showing as these will act much like a glow plug too. It's a simple matter to change the plugs installed height with different washer thickness'

Blend all sharp edges in the chamber

I hope this helps