Off with her head!

Post by **alex_holden** » Fri Oct 12, 2007 8:33 pm

No, it's definitely Moorespeed. The chap I dealt with is called Ian. Apparently he used to have a Minor with a highly tuned 1098 engine.

Post by **bmcecosse** » Fri Oct 12, 2007 8:39 pm

Ok - wondered about the Padiham reference which is more MiniSport connected! Good luck with the head !

Post by **alex_holden** » Sat Oct 13, 2007 6:09 pm

I think it's cured. I ran it for 20 minutes at 2000RPM with no obvious signs of leakage. Unfortunately because I changed several variables at once I can't say for sure which one(s) were significant:

* I had the head skimmed. The guy who did it said it wasn't flat before, and the surface finish was quite rough.
* I replaced the studs, then I trial-fitted the head with no gasket and checked there was thread still showing so the nuts definitely weren't going to bottom out.
* I used a Payen head gasket. As well as the previously mentioned lacquer coating on both sides, it appeared to squish down a bit more than the standard gasket.
* I greased the surface of the head and block.
* I oiled the threads on the studs.
* I torqued the nuts down to 44 lb/ft instead of 40.

After a good clean to get rid of the grinding dust (don't tell my mum but I stuck it through a dishwasher cycle

) I had a close look for evidence of the hardened exhaust seat inserts and I think I found it. The transition from one to the other is nearly invisible - there's no step on the combustion chamber side because the face has been recut after insertion. I still think the exhaust valves must be the standard sort because of the pitting (in hindsight I should have ordered a set of the unleaded type at the same time as the head gasket and studs).

Post by **bmcecosse** » Sun Oct 14, 2007 12:46 pm

Well done - tighten it down again after a few heat cycles - and reset the valve gaps. I prefer 15 thou for exhausts to make sure they don't close up during hard running.

Post by **Orkney2** » Sun Oct 14, 2007 1:18 pm

Well done Alex ! Hope it copes with your driving

Off to think up a suitable blackmail plot to flog me Fenchurch for £500 now youve made public the dishwasher abuse

Post by **aupickup** » Sun Oct 14, 2007 2:58 pm

the head gasket should be fitted dry, no grease or anything like that

Post by **aupickup** » Sun Oct 14, 2007 3:00 pm

i think the surfaces should be put together without grease, and make sure the gasket was the right way up

Post by **bmcecosse** » Sun Oct 14, 2007 7:44 pm

My advice - from many years experience with A series engines incuding some very high powered units - is thin film of grease on both faces..

Post by **aupickup** » Sun Oct 14, 2007 7:53 pm

might try that next time, tho i have never had a problem dry fitting

Post by **millerman** » Sun Oct 14, 2007 8:22 pm

BM

What's the thinking behind using grease when fitting cyl head gaskets?

Post by **bmcecosse** » Sun Oct 14, 2007 8:47 pm

Dunno really - maybe lets the gasket ease into place a little better - and seems to stop it sticking to the head/block so easy to come off. It's just the way I was told many many moons ago - I've always done it - and only ever had one blown head gasket - the day after MOT garage boiled my engine almost dry! It had no cooling fan and they left it idling for 3/4 hour during the whole test.

Post by **aupickup** » Sun Oct 14, 2007 8:55 pm

what happens to the gtrease when it gets hot

Post by **MoggyTech** » Sun Oct 14, 2007 9:00 pm

aupickup wrote:what happens to the gtrease when it gets hot

With the older paper and asbestos gaskets the grease used to soak into the gasket. Back in the 70's I was told by numerous mechanics to use grease when replaceing a head gasket.

These days my gut feeling is no grease, especially with the Payen gasket, as there is no where for the grease to go, other than to burn into a sticky mess between the metal gasket face and the head/block.

Post by **bmcecosse** » Sun Oct 14, 2007 9:43 pm

I have always used copper/steel head gaskets - NOT the ghastly 'cardboard' ones!!

Post by **eastona** » Sun Oct 14, 2007 10:06 pm

I always make sure both surfaces are really clean, making sure no remaining old gasket material, including around holes / studs, then use a thin film of grease.

only time I've had trouble was mainly through not cleaning properly (in too much of a hurry

).

Andrew

Post by **alex_holden** » Sun Oct 14, 2007 10:13 pm

Well it was certainly very clean every time I assembled it. I suspect the two failures were mainly down to the head being out of true (badly skimmed in the past).

Post by **Kevin** » Mon Oct 15, 2007 4:12 pm

It now has a nice ground surface finish with some very slight pitting around the water galleries rather than the deep flycutter marks it had before.

Seems strange that it had not been ground in the first place but stil at least its now solved the problem and 8 thou is quite a bit out for a head.