Convex and concave tappet chest covers

[Declan_Burns]

Does anybody know which cars were fitted with convex and which cars were fitted with concave tappet chest covers?
There seems to be a lot of confusion. The rubber seal that I make fits the convex cover. Some websites state that the thin cork seal is only for the convex cover whereas they state that the neoprene red rubber seal fits all. This I cannot believe.
Regards
Declan[frame][/frame]

[bmcecosse]

As far as I know - the change came with the 1098 engine. It uses the much better neoprene joints - the 803/948 using the cork joints. The neoprene joints will not satisfactorily seal on the early covers since there is no lip to retain them from spreading outwards. I suppose they could be 'stuck' on - but seems pointless. The cork joints work perfectly well on the early covers if carefully assembled - and not overtightened.

[philthehill]

Pt No: 12A1139 - cork gasket for convex cover.

Pt No: GUG705505GM - rubber gasket for concave cover.

I have used the cork gasket on a concave cover but the rubber gasket is not suitable for the convex cover because as bmc says above there is nothing to locate the rubber gasket.

I have attached a link to the Somerford Mini web site which gives some details of the different covers used with year dates. Their use on the Minor engine 803cc / 948cc / 1098cc is not much different and in the majority of cases can be cross referenced.

http://www.somerfordmini.co.uk/eshop/in ... age&id=108

Full details of covers used can be found in the Somerford Mini catalogue which unfortunately has to be purchased.

[Declan_Burns]

Phil,
I'm still confused. The photo below above shows the rubber gasket on the concave cover and it seats very well. It cannot go anywhere as it sits against a ridge in the cover. The Somerford website is also not concise. They state 1963 ... 1966 convex Part 12H941 and 1966 on concave 12A1386.
Back to my original question.
Which cars had the concave and which cars had the convex covers? Which style was the early and which style was the late?
Are they interchangeable?
I would appreciate it if a few people could check their model year and style of cover.

Regards
Declan

Convex cover with rubber seal[frame][/frame]

[philthehill]

Declan
No wonder you are confused. Some of the parts catalogues incorrectly list the covers - so until I have confirmed the part number I will leave the unconfirmed part numbers out.
The early cover was convex 803cc/948cc (Pt Nos: (F) & (R)) and the later covers 1098cc (Pt Nos: (F) & 12A1386 (R)) were concave.
I cannot give you the precise engine number change over but any engine with a engine number prefix of 2, 8, or 9 should be fitted with the early convex covers; and engines with a engine number prefix of 10 should be fitted with the later concave covers.
The covers are interchangeable provided you have / use the complete assy i.e. cover and (if fitted) pipe.
Therefore as they are interchangeable early cars could have been fitted with concave covers.
There is little point in fitting early covers to the later 10 prefixed engines as the later covers were a better cover in that they did not so easily distort when tightening the securing bolt.
The easiest way to identify the covers is that the concave has a rolled return on its outer edge and the convex does not.
There are several types of later concave cover (including those fitted with oil separator) fitted to the 'A' series.
As regards the rubber gasket - only fit to a cover that has the rolled return on its outer edge i.e. concave.
Phil