Help! engine spitting and backfiring.

[bmcecosse]

Unless you make changes to the 948 - it won't really benefit from the larger carb, and as it's oip pressure is 'marginal' - any extar power would only hasten the end! If you want to improve the 1098 before fitting it - look for a better camshaft (MG Metro is ideal - but needs a different oil pump) and a 12G 295 head - or better still - a 12G 940 head! For best power - you don't water heat the manifold - leave it cold.

[williamraff]

Right, I was wondering about that.I couldnt understand why the manifold is heated when by all accounts the colder the incoming air the better? Do I just blank of the heater pipes then?
I have been watching 12940 heads on ebay but i am bit worried about "pocketing" not sure what is involved there and it sounds expensive?
Regards,Will.

[bmcecosse]

You 'may' have to sink the exhaust valvs into the head - by 40 thou. But - many find there is clearance without doing this. It is by far the best head. If you see one at the right price - loacl to you so you don't have to pay £15 carriage - grab it. They are going up in price at the moemnt - so it's bound to be a good investment.