1275 head waterways

linearaudio · Post by **linearaudio** » Fri Oct 10, 2008 7:52 pm

OK- I've got a 1275 head from a Metro turbo, (33mm inlets, hardened exhaust seat inserts) which is destined for the top of my 1098, but am a little unsure about the waterways. three of them on the opposite side to the manifold face have got blanking plugs in, presumably to give a greater flow to the hot areas. Do I leave them in situ for a lowly 1098, or remove them?<br>

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Oh, and what is the best 1275 head gasket to use; copper, composite etc?

Post by **bmcecosse** » Fri Oct 10, 2008 8:57 pm

Use any gasket - and no goo. Just a smear of grease on each face. Leave all plugs in - place the new gasket on the block and compare to the block water passages - I found there was one hole in the block where there is no hole in the gasket - so I put a blob of silicon sealer in the hole - and on with the gasket. That was several years ago now. I've not used a Turbo head before - it has sodium filled exhaust valves which have a larger stem diameter than normal(if it really is a Turbo head) - in the picture the exhaust valve guide showing doesn't look to be any larger than normal ? Are you sinking the valves by 40 thou ? Or you can do a trail assembly with blobs of plasticine under the exhaust valves - then turn it over gently on the handle - then remove head and see how thin the plasticine is ! You must use 1275 rocker assembly - or, carefully re-arrange the rockers on your existing set so they act directly on the tips of the valves.

linearaudio · Post by **linearaudio** » Sat Oct 11, 2008 9:05 am

Thanks for all that, BM. I've just had my own doubts about the "turbo" bit- think it's late(post 89) standard now. Will certainly trial run the valves and get a compatible rocker shaft as I don't want to alter any of my existing 1098 bits! Do I need to modify the top of the waterpump housing to clear the head? Think I've heard mumblings about that from some sources.

Post by **bmcecosse** » Sat Oct 11, 2008 9:37 am

Yes -with some water pumps you need to run a file across the top to get clearance - only takes seconds and can be done on the car.
The 'turbo' head is no better than any other 940 head - except it has these extremely expensive sodium filled exhaust valves. Ideal if going turbo or super, but no advantage normally. the 1275 rockers only 'work' because they are great fat sintered things which spread across to hit the valve tip - but the forces are diagonally across the rocker and it's far from ideal. Optimum is to use a set of 1098 'pressed steel' rockers - and spend a little time setting them up so they act directly on the valves. This reduces side-wear on the valves and guides - and is quite satisfying to do !

linearaudio · Post by **linearaudio** » Sat Oct 11, 2008 3:02 pm

Cheers. I didn't consciously go out to get a turbo head(which it appears not to be anyway) it was just the only decent one in the yard without breaking a complete engine. Valve stems are std size. I like having the hardened seats "thrown in" as thats another niggling worry to cross off!

Post by **bmcecosse** » Sat Oct 11, 2008 5:03 pm

Are they hardened seats ? They wouldn't normally be hard on a head of that age (it has a bypass connection!) - but may have been fitted aftermarket. Fine for unleaded running - but you will struggle to sink the valves!

linearaudio · Post by **linearaudio** » Sat Oct 11, 2008 6:56 pm

Yep, reckon they're aftermarket as they look quite neat! Now- what about the pipework? Top rad hose looks as though it might be a tad short as the thermostat casting fits pointing more to the rear, or is there a another housing which lines up differently? Also- the heater pipe connection at the rear of the block isn't opened out. Do I open it up & use it or is there a better/different arrangement eg as used on the application the head came from?

Post by **wanderinstar** » Sat Oct 11, 2008 7:34 pm

I have heard that the t/stat housing from an MGB fits and lines up better. You can't use the 1098 heater valve, it catches on the battery. So use the earlier handwheel valve.

Post by **bmcecosse** » Sat Oct 11, 2008 8:03 pm

Yes - there are other stat covers that line up better - I just used a bent pipe cut from a bottom hose. Drill through the heater take-off, and run a 1/4" unf tap down the two little holes - they are drilled and tapped already (no wonder Rover lost money) but have never been used - and as Ian says you need the wheel valve or just the simple stub pipe with no valve used on some Mini models - you should never shut the water off anyway.

Post by **rayofleamington** » Sat Oct 11, 2008 9:48 pm

Just a smear of grease on each face.

nooooo!

Post by **bmcecosse** » Sun Oct 12, 2008 5:01 am

Smear of grease has never let me down - from an 848 Mini to a 1340 8 port head !

linearaudio · Post by **linearaudio** » Sun Oct 12, 2008 7:08 pm

Eight port Moggy, proper tuned pipe lengths-whooo, steady now! I feel all dreamy

Now, back to the 940 head with a bump!! By jjjjjiggling the rockers, would you mean a suitable shim/washer to each exhaust side of the pillars, BM? Doesn't look to be much more than a bit different(40 thouish sort of order). Has anyone got the "exact" difference in centres, and is it just the exhaust that has moved? Questions, questions. Just trying to get as much clear in my muddly old head before I jump in.

Post by **bmcecosse** » Sun Oct 12, 2008 7:21 pm

The 8 port was a full race Mini - actually one of the very first - supplied to my mate as part of a semi-works sponshorship deal he had at the time for TV Rallycross. It ran 2 x 40 Webers, 4 branch lcb exhaust, 320/320 supersprint cam - and yet it was extremely docile to drive - but went like you-know-what off a shovel!
Yes the exhausts have moved - you may have to use washers and/or file away part of the side of the rocker to get them properly lined up. The inlets should be not too bad - but may benefit from some fine 'adjustemnt'. The washers from the ends of the rocker shaft - just under the spilt pin - are ideal!