11 replies to this topic

[lukepinfield]

Just bought a 1098, the pistons in the engine currently sit flush with the top of the block and are dished.

I have used a 12g295 cylinder head on my 998 and so know it is a good head, however.

I am unsure if the valves with hit the pistons is there anyway of checking

[oltonlad]

the 295 head will be fine with the 1098, you will have to take another 20 thou from the head though as you normally only need to take 60 thou off a 295 to suit a 998 with flat topped pistons, a 1098 with dished pistons needs 80 thou taken off a 295 head.

[bmcecosse]

A 12G 940 head is MUCH better on a 1098.......and doesn't need any skimming. Just make sure the exhaust valves have 320thou clearance to the head surface.

Edited by bmcecosse, 16 June 2012 - 04:06 PM.

[oltonlad]

A 12G 940 head is MUCH better on a 1098.......and doesn't need any skimming. Just make sure the exhaust valves have 320thou clearance to the head surface.

hahaha.......i knew that you would be along with the 940 suggestion bmc......................
i know of a guy with a similar spec engine to mine but he used a 940 on his engine.............but my engine still produces more power and torque than his.

Edited by oltonlad, 16 June 2012 - 04:13 PM.

[bmcecosse]

That's because it IS much much better....I removed a well modified 295 and fitted a slightly modified 940 and the difference was amazing.......

[Boycie]

Worth mentioning, if budget is of most importance, the 12G202 head fitted to the 1098 as standard is a good head, probably nearly as effective as a '295 on an otherwise stock engine and no machining needed!

[oltonlad]

That's because it IS much much better....I removed a well modified 295 and fitted a slightly modified 940 and the difference was amazing.......

well my mates 1098 with the 940 must be built wrongly then because my mini trounces his easily........and i'm using a 295.

[bmcecosse]

His must indeed be in a bad way!

[lukepinfield]

I have been toying with the idea of a 12g940 cylinder head, how will I check the clearance once it's on??

[oltonlad]

I have been toying with the idea of a 12g940 cylinder head, how will I check the clearance once it's on??

you cant, personally the idea of using a cylinder head where you have to sink the valves, have waterways that don't line up properly and having to use a 1275 head gasket on a small bore engine to make it work baffles me.

[bmcecosse]

Hahaha - the extra power will soon convince you..... You check the clearance BEFORE you fit it. Measure depth of exhaust valves from the head surface. They must be 320 thou down for a standard cam - up to MG Metro.

[lukepinfield]

I think I will run with the 12G940, what head gasket will be required?? and will mods to water ways and etc be required??