head gasket update

[Onne]

I removed my head today. Went quite easily, certainly for a first timer like myself.
I'll let the piccies do the talking, but note the original low compression pistons, and the pound of carbon deposit on the head and valves

And it is quite obvious where my gasket went. The stem seals were quite dead as well, certainly on the inlet side





what do you lot recommend, should I get the head skimmed?

Onne

[bmcecosse]

No no - spend the next week carefully scraping it till it's perfectly flat!

The gasket has only slightly blown - usually it gets ripped away completely!!
Clean it all up and check with a straight edge (12" (300mm in foreign parts) steel rule - or even the back of a new hacksaw blade) with a bright light behind it. Exhaust valves look very white - maybe running slightly weak - what do the plugs look like ? Pistons look fine - and the carbon you see there is perfectly normal. The inlets look quite big - is it just a 12g202 head - or is it a 206/295 ?? And I may be wrong - but it looks like the ghastly convoluted by-pass hose - if so - GET RID OF IT!

[doobry]

Well, I'd consider getting the head skimmed although the gasket was only a mild failure, so that's just being cautious.

As for this 'pound of carbon deposits?? Where????
You'll now a big carbon deposit when you see one - modern fuels seem better than the stuff in the 50s to 70's - in those days you needed to do a dekoke after 50,000 miles because you had serious heavy deposits.

Exhaust vales - same comment as above, they look very white. Either it's a trick of the camera and they are beige, but if they really are white then mixture was too weak. That wqould cause hot running and not help the long term life of the head gasket etc...

From the picture it isn't possible to see the dish in the pistons - are you sure they are low compression? normal pistons are dished a few mm but low comp pistons are VERY dished.

[Onne]

the exhaust valves are beige, not white. The head is a 12g202

I wil try and make another picture of my pistons, but they are very dished.

thanks for the help

[bmcecosse]

Aye they look quite dished - so if you do decide to skim the head - take off a good lump - 60 thou - to help the comp ratio. The chamber shape does say 202 head - just the inlets look quite big and very badly shrouded by the chamber walls - I had forgotten how bad a standard head is !! Try to find a 206 or 295 head for it - this is the chance to upgrade.
Ian - do you not still have a 206 head for sale ?

[Onne]

I don't see the need for an upgrade. I think it is quite good as it is.

I wil get it skimmed though, I'll ask for 40 thou, to be on the safe side

[bmcecosse]

60 thou won't cost any more - and it all helps the fuel economy.

[Onne]

True, but first I will have it checked for trueness. If it is still flat as can be, I don't see the need for a skim. I will get the valves reground though!

[chrisd87]

Perhaps you could use this opportunity to put some high compression pistons in there?

[Onne]

I don't want to offend any people with this comment, but why? I don't see the need for an upgrade, the good gasket itself will be an upgrade.

I find the power very adequate, and I'm not sure if I would even like more power. I find driving my Minor very relaxing, gets my nerves down, no stress for a bit.

In one word. JOY

[bmcecosse]

It will certainly save excess wear on the engine - but it does have a negative effect on economy - but maybe fuel where you are is not as expensive as here at very near £1/litre. I agree Onne - if it's flat, leave it - but if it needs skimming - go for 60 thou. HC pistons are all very well but will cost a fortune. Unless doing a re-bore anyway - don't bother.

[Onne]

I completely agree!