12G940 head and LCB

[moggiegeek]

Am gathering the bits to squeeze a few more HP out of my 1098. I have the 12G940, with the requisite 320 thou clearance between valve head and base of cylinder head, MG turbo gasket (Payen), cooper rockers 1:27, water heated inlet and 11/2 inch SU.
I have been given a LCB,however I fear it may be too big at two inch diameter and in fact make the engine less efficient.
Is this the case?
And what additional components might I add to assist? i wonder also if standard moggie push rods are OK as I know cooper ones are longer. I know a MG metro cam and oil pump would help but rather put off dismantling the engine. All advice gratefully received.

[chrisryder]

reuse the minor pushrods, they'll be 'mated' to your cam followers.

2 inch sounds mighty large, it'd only really be suitable for a high performance 1275 (1380 etc)

I've got a 1.5 inch LCB on my 1098 with 1275 head and that's probably overkill, to the point of being detrimental. Maniflow do a 'small bore' lcb which is slightly smaller, designed for tuned 948s and 1098s.

The only other thing i'd add to your list is whatever air filter you're going to use. I'm a K&N fan myself.

[bmcecosse]

DO NOT use the 'turbo' gasket - standard 1275 gasket is fine. You must use 1275 sintered rockers, or spend some time re-aligning the pressed steel rockers to act directly on the valve stems. Skim a bit off the water pump top surface (hand file is fine) and don't 'water heat' the manifold....... 'Cooper' push rods are NOT longer - but 1275 ones are.......too long for a 1098 engine !! Your choice with the LCB - but frankly - this level of engine mod doesn't need an LCB - which only comes into it's own with a longer period cam.

[moggiegeek]

Thanks for the advice - out of interest - why not the turbo head gasket? One tends to get pretty conflicting advice from suppliers.
I guess at a later date when I fit MG metro cam/ oil pump then the LCB comes into its own. Again you get conflicting advice - doesn't LCB give you less constriction or does this only come into play when you have different valve timings and periods open?
Fitting a K+N filter and have sintered rockers.
Not water heating the manifold gives you a lower temperature charge or is it to stop icing?
Good to learn this stuff.

[bmcecosse]

No need for the expensive turbo gasket - so don't waste cash! Water heated manifold does nothing for carb icing - it's down stream of the carb - no hope of the heat travelling back up to the carb..... LCB will lose you power - even on the MG cam. Good with 544 cam though!