1098 Engine modifications

[bmcecosse]

Yes - that's all we did - cutter revolving at slow speed and letting the head self centre on each exhaust valve seat - it's ONLY the exhausts you need to do. We also put a piece of emery paper in with the cutter which apparently stops any chatter. Certainly made lovely seats on my 940 head. But - do measure first - you may well not need to do anything. Can only suggest Gumtree - something like that? Or of course autojumbles. Used to pick these up for £10 to£20 - but the popularity (I wonder why??) of fitting these heads to 998/1098 engines seems to have raised the value somewhat.

[Tomz]

You need 1275 rockers on that head and definitely NO double springs !!

No double springs because of the higher pressure on the whole system?

Tom

[MarkyB]

The theory behind double springs is to stop valve bounce at high revs, pressure isn't an issue.

[Tomz]

The theory behind double springs is to stop valve bounce at high revs, pressure isn't an issue.

Yes, but the reason to NOT use double springs? Written in UPPER CASE..

As the cam shaft and the whole rocker system has to overcome the pressure or force of the double springs on the valves I thought that this higher force may be an issue with the Morris engine.

[bmcecosse]

You are not going to be using high revs - therefore you use JUST enough spring force to get what you want - yes - reducing the drag on the whole valve train saves wear and power!

[John.n]

I have ground to a bit of a halt with the engine rebuild. 3 of the head studs wont come out. tried 2 nuts back to back and lost of plus gas but had no sucess. any top tips?
Regards,
John

[bmcecosse]

Apply some HEAT. But why do you need the studs out? Which ones are causing the problem?

[John.n]

it is the front 3 on the opposite side to the oil filter that are stuck.
I was trying to remove the, to turn the engine upside down to work on the sump.
been looking on ebay again a some cylinder heads and found this;

http://www.ebay.co.uk/itm/CLASSIC-MINI- ... 4d08b06d00

Is this a suitable replacement head or will it not fit?

I have bought a timing chain kit and im wondering how to fit the rubber ring chain tensioners in the gear?
do i just need to cut the old one out and strech the new one into place?

Regards,
John

[MarkyB]

Buy a stud extractor if heat doesn't do the trick.
While you have it apart I'd upgrade the timing chain to a duplex set up rather than bother with the simplex chain and hopeless rubber bands.
Other timing chains options are also available

[John.n]

whats the advantage of a duplex timing chain other than added strength? not like the timing chain is a weak link, excuse the pun. are others quiter? plus I have already bought the kit. the duplex chain kit needed some faffing to fit so decided against it.

Regards,
John

[bmcecosse]

You don't buy a new cylinder head just because 3 studs (I assume the thermostat 3) won't come out at first tug!!! And no - that's a (stupidly expensive) MPi head........ Take the head off if you want a flat surface (the block face) to turn the engine upside down - but anyway - it's easier to work with the engine on it's side - not upside down..... And a bit of heat WILL pop the studs (if you really must) - and yes - the rubber bands are useless.... The sprockets will also be badly worn (esp the small one) with sharp/pointed teeth, so a new chain is probably a waste of money unless also fitting new sprockets. The Mini set up with single chain and rubber block tensioner is by far the best for a 'standard' engine - but most go for the duplex system since they feel they are 'upgrading' their engine by fitting it!!

[bmcecosse]

What is in the 'kit' ????

[MarkyB]

Any modification is likely to require some faffing about, it's minimal with the duplex chain, just countersink 2 bolt holes.
The single row chain and rubber bands is likely to start rattling again after a couple of years or so.

[bmcecosse]

Couple of years ??? More like couple of miles.....

[John.n]

what stops the duplex chain rattling?
the three stuck head studs are in the block not the head. was thinking of replacing all the studs as a matter of course
Regards,
John

[MarkyB]

The duplex set up is over spec and so wears very little.
The studs shouldn't need replacing, stretch bolts were unheard of when this engine was designed.

[les]

There was a recent post here showing a stud that had stretched! So replacing them is not such a bad idea. I had to smile when you mentioned your reluctance to 'faff' about. Won't be long before you out the Minor then!

[bmcecosse]

Ahh -well that would be 'block' studs then... Release oil and heat then...... They tend to be loose - not tight - due to the relatively course UNC thread in the block.

[John.n]

these three studs seem corroded compared with the others not sure why though. waiting for a suitable head to apar on ebay at the right price. missed the other one. should I avoid larger inlet valves?
Regards,
John

[bmcecosse]

Indeed yes - avoid the 35 mm inlets - the 33 mm are plenty big enough for a 1098. I thought you said you already had a 940 head on the engine?? Oh dear - prices seem to have risen!! I wonder why - has someone been promoting the use of these heads??? I know there is a cheap big valve head on ebay at the moment - bid on it if you wish - but it won't be cheap at the end !! And if it is - I'll have bought it.......