8 replies to this topic

[not so mini]

Can anybody tell me what 998 engines had flat top pistons fitted as standard? If any.

I have been told that they were in Metros?

Any Ideas Cheers

[mini_mad69]

All my 998 engines have had flat top pistons, ive had three but ive had one 1985 engine on a c reg, one d reg engine, and one 1987 d reg engine.

[Big_Adam]

I got two that have, one with domed in pistons.

So .. I go no clue.

[mini_lad_1990]

from reading about some having and some not would it be on the a and a+ series engine??

[mike.]

They came standard with flat top pistons. From my previously asked questions i've learnt that cooper engines had domed pistons to raise the compression ratio to allow fitment of a 12G295 head which was originally designed for 1100 engines with a lower CR.

[[email protected]]

Incorrect, there are lots of 998cc's around with dished pistons. Most standard 998's up until 79 would have had dished, as would any economy built units with the lower CR ratio after that time

[not so mini]

So it seems it's a bit of a scatter pattern.

Reason is I have a 12g295 head I'm rebuilding and I want a flat top engine as mine is dished so I can get the compression back up to where it should be after fitting the bigger head.

Will have to keep taking heads off engines

[mike.]

So it seems it's a bit of a scatter pattern.

Reason is I have a 12g295 head I'm rebuilding and I want a flat top engine as mine is dished so I can get the compression back up to where it should be after fitting the bigger head.

Will have to keep taking heads off engines

Even with flat top pistons the CR will still be too low. Usually you'll have to get the head skimmed.

[Ethel]

Head skimming will still be in order (as Mike says) if the head is still as standard.

Economy versions of the A+ had flat tops - Metro HLE, Mini City E and possibly some others. The Metro is easiest to spot on the car as it has the twin downpipe manifold.