Morris Minor Owners Club

The engine is now out my car, and im slowly starting to take it to pieces.
It has a GENUINE 6,000 miles on it, but because im evil im going to fit a 12g940 head, HS4 carb, 1098 cam, multi-branch header and big bore exhaust system to it......

So, what do i need to replace/fit to the engine to make sure that it doesnt blow up in me face the first time i take it out and also ensure i retain some kind of reliability?

cheers,
YG

Personally I would replace the oil pump with a new one regardless of mileage, fit double valve springs if you're going to rev it and duplex timing chain and gears to cope with those extra pressures - that installation is covered a lot in here. You don't mention which inlet manifold you're using but it will need to match the carb for good airflow. I take it the new head has been polished and the combustion spaces are the right size for the cubic capacity - also covered well in here. Not familiar with the 1098 cam if not standard?

Personally I might change the oil pump, but I wouldn't do valve springs or duplex chain. I reckon the crank would give up long before either of those were having any influence at all - but I'm no expert.

If it really IS 6000 miles - leave it alone. But is this 6000 miles from BRAND NEW, or 6000 miles since someone 'reconditioned' it? You really don't want double valve springs - the oil pump IF 6000 miles will be fine. Are you aware of what needs doing to fit the 940 head ?

bmcecosse wrote:If it really IS 6000 miles - leave it alone. But is this 6000 miles from BRAND NEW, or 6000 miles since someone 'reconditioned' it? You really don't want double valve springs - the oil pump IF 6000 miles will be fine. Are you aware of what needs doing to fit the 940 head ?

I believe the valves have to be sunk in by 40 thou, and therefore some 40 thou washers put under each valve spring. Does any porting work need doing?

Oh, and the engine is a factory recon (goldseal) with 6,000 on it.

Excellent - yes that's what you need to fit the 940 - with 1275 head gasket of course, and you need to align the rockers carefully with the valve stems, or use the later (horrible) sintered rockers which are wide enough to straddle the valves - but are then operating 'off-centre' which is not ideal, but will be ok for a non-competition engine. If the cam chain etc is new, don't bother with duplex. But if you do buy new, may as well go duplex!

I believe the valves have to be sunk in by 40 thou, and therefore some 40 thou washers put under each valve spring.

Having a bad day here but what are the washers for.

cleaning the windscreen I think

cleaning the windscreen I think

The packing washers restore the preload on the valves to make sure they shut well. I didn't bother, but I used double springs.

But why do you need them Roger as they were not there in the first place so how is the preload alterred on the head

The preload has altered if he's sunk the valves 40 thou ;)

Right I`m with you now (told you I was having a bad day) I miss-read it to mean that the block was going to be pocketed rather than the valve seats.........................

bmc how much do you gain by fitting the 940 head is it worth doing,I've got one and mine is due a valve job soon just curious

Well, you have to use the head in conjunction with a larger carb/manifold etc to make full use of it. But from what ive heard the power and torque increase can be quite considerable.

It's like a 'stage 4' head - so could release 10 or even 15 more bhp from your engine - with the bigger carb and inlet manifold. If you just fitted it with all the original gear - the gains would be smaller but still maybe 5 bhp - the carb etc strangliing it at high revs. Would lift the mid-range power usefully.