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Just looking at the pics posted here and people's comments I wonder if there could be more a problem with the cylinder heads expanding [IE lifting] from thermal expansion on the small area.
If the small bore engines are blowing thru 1-2 and 3-4 and the big bore engs are going thru 2-3.
It may not be the compound of the metal but if there is some lifting then no matter what metal is there it will eventually track thru.
The other day I was looking at some pics of 2 stroke diesel engines with stellited valves and seats but both had suffered from sulphur vanadium hot corrosion where is cut thru the stellite like it had been cut with a plasma cutter. This was usually caused from a slight clearance when the valve was not seating.
The fire rings are the problem not the rest of the head that just needs sealing for the water pressure.
May be the fire rings need more pressure at the narrowest point. Its something I found with my honda head conversion where I use a annealed copper ring but with .4mm compression above the rest of the plate.
The cylinder heads may be perfectly flat but if lifting is a problem with higher compression then maybe the head might need a thou or two taper from the centerline to the outer edges to give more compression in the center.
Just another mad idea.

Author:	drmini in aust [ Fri Jun 11, 2010 5:13 pm ]
Post subject:
FWIW- It is general practice on alloy head/iron block European engines (Fiat, Lancia, etc) to use a composite gasket.

Author:	Phat Kat [ Fri Jun 11, 2010 5:14 pm ]
Post subject:
drmini in aust wrote: FWIW- It is general practice on alloy head/iron block European engines (Fiat, Lancia, etc) to use a composite gasket. Yeah, was just thinking the same thing actually regarding Jap motors.

Author:	david rosenthal [ Fri Jun 11, 2010 6:54 pm ]
Post subject:
Just looking at the pics posted here and people's comments I wonder if there could be more a problem with the cylinder heads expanding [IE lifting] from thermal expansion on the small area. If the small bore engines are blowing thru 1-2 and 3-4 and the big bore engs are going thru 2-3. It may not be the compound of the metal but if there is some lifting then no matter what metal is there it will eventually track thru. The other day I was looking at some pics of 2 stroke diesel engines with stellited valves and seats but both had suffered from sulphur vanadium hot corrosion where is cut thru the stellite like it had been cut with a plasma cutter. This was usually caused from a slight clearance when the valve was not seating. The fire rings are the problem not the rest of the head that just needs sealing for the water pressure. May be the fire rings need more pressure at the narrowest point. Its something I found with my honda head conversion where I use a annealed copper ring but with .4mm compression above the rest of the plate. The cylinder heads may be perfectly flat but if lifting is a problem with higher compression then maybe the head might need a thou or two taper from the centerline to the outer edges to give more compression in the center. Just another mad idea.

Author:	Asphalt [ Fri Jun 11, 2010 7:04 pm ]
Post subject:
The Cometic gaskets have, as they write on their site, a gas filled fire ring which expands under heat to obtain maximum seal, even if lift occurs. Sounds like a good idea too http://www.cometic.com/phuzion.aspx I too had one of these faulty Payen gaskets; it looks axectely like the bottom one on 850man's picture; http://i605.photobucket.com/albums/tt13 ... 110003.jpg

Author:	Phat Kat [ Fri Jun 11, 2010 7:15 pm ]
Post subject:
david rosenthal wrote: Just looking at the pics posted here and people's comments I wonder if there could be more a problem with the cylinder heads expanding [IE lifting] from thermal expansion on the small area. If the small bore engines are blowing thru 1-2 and 3-4 and the big bore engs are going thru 2-3. It may not be the compound of the metal but if there is some lifting then no matter what metal is there it will eventually track thru. The other day I was looking at some pics of 2 stroke diesel engines with stellited valves and seats but both had suffered from sulphur vanadium hot corrosion where is cut thru the stellite like it had been cut with a plasma cutter. This was usually caused from a slight clearance when the valve was not seating. The fire rings are the problem not the rest of the head that just needs sealing for the water pressure. May be the fire rings need more pressure at the narrowest point. Its something I found with my honda head conversion where I use a annealed copper ring but with .4mm compression above the rest of the plate. The cylinder heads may be perfectly flat but if lifting is a problem with higher compression then maybe the head might need a thou or two taper from the centerline to the outer edges to give more compression in the center. Just another mad idea. It is true, that on most of the big bore motors I've pulled down that they do have signs of breach between 2-3... even with perfectly machined blocks/heads, even with out ANY sign of gasket failour... But I must say, that people have been running high comp ratios in these engines since they first came out (granted with varried results).... But it seems odd that even if there is an inadiquecy in the way which these engines are machined.... that some fail where others don't? They're all snow ground, flat,,,,,, so even if YES they should have a slight kanter from either side towards the centre, a lot of them don't blow or stuff up, while some do..... the only varriable is the gasket.... (well that and the preassembly checks that are MEANT to be carried out)

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head gasket https://www.ausmini.com/forums/viewtopic.php?f=2&t=56964	Page 5 of 5

Author:	cooperess [ Thu Aug 04, 2022 11:43 am ]
Post subject:	Re: head gasket
Having read all the comments, I have bought a Permaseal AF470 $62 for my Mk2 .060 over sized pistoned motor and will let you know how it goes. I will do a compression test after fitting and then another after a few short runs.

Author:	MINIRO [ Tue Aug 16, 2022 4:37 pm ]
Post subject:	Re: head gasket
I have recently had a 1098 built - block and head machined. Copper gasket went poop very quickly... having said that, i have since gone to a composite gasket that let go due to the head studs stretching... So at this point, i wont blame the original copper gasket as im unsure when the studs gave out.

Author:	timmy201 [ Tue Aug 16, 2022 6:22 pm ]
Post subject:	Re: head gasket
There’s a recent thread here on poor quality studs viewtopic.php?f=2&t=101407 There are a few things you can do to try and get a good seal, running on water for a while, retorque the head hot etc

Author:	MINIRO [ Tue Aug 16, 2022 9:13 pm ]
Post subject:	Re: head gasket
timmy201 wrote: There’s a recent thread here on poor quality studs https://www.ausmini.com/forums/viewtopi ... 2&t=101407 There are a few things you can do to try and get a good seal, running on water for a while, retorque the head hot etc Thanks mate..

Author:	cooperess [ Thu Sep 01, 2022 4:12 pm ]
Post subject:	Re: head gasket
No1,2,3 = 160PSI No4 165PSI. Is that OK?

Author:	gtogreen1969 [ Thu Sep 01, 2022 5:06 pm ]
Post subject:	Re: head gasket
cooperess wrote: No1,2,3 = 160PSI No4 165PSI. Is that OK? Yes

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