1098 "FrankenEngine" - advice please on breathing

Side valve, 803, 948, 1098., 1275 and Vizard mods
Hi all - board newbie here responsible for spannering the MM owned by t'wife...

We have a split screen MInor that has been 'upgraded' over the years by different owners (no real paperwork on those upgrades with the car). The engine is a 1098cc and the engine number would place it as a late (Hi-comp) one. However the head is red in colour and there is a Minispares heated inlet manifold fitted with what looks like an MG Metro carb (well it is a big SU carb with three blanked off vacuum inlets and an MG badge glued onto it). The vaccum fitting on the Minispares manifold is taken up with the brake servo vacuum pipe. Vented oil filler cap fitted

Currently the rocker cover breather pipe is vented into the engine bay - my thoughts are that this should be looped over and onto one of the three available inlets on the carb mounting most likely the one with the large bolt in the image below???

Graeme

IMG_20170718_093746.jpg
GraemeT
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I suspect that a 1990s Mini/Metro cylinder head from an A+ engine has been fitted (these were often painted red from the factory), possibly a 12G940 one from a 1275cc (if you're lucky!) - what is the part number stamped on it (should be under the rocker cover, near the thermostat)?

The carb is a HIF type, as fitted to 1990s Minis, Metros, etc.

There are two variants of this, the HIF 38 (1.5") and HIF 44 (1.75"). You need the HIF 38 on a 1098cc engine, but beware of the super-eco version as fitted to the Metro 1.0E, as they were designed to run extremely lean, which probably won't suit a 1098cc engine.

This thread from the other side shows how the various pipes should be connected:

http://www.mmoc.org.uk/Messageboard/vie ... hp?t=33558

I.e, the middle of those three take-offs should be connected to the crankcase breather canister or breather from the rocker cover.

I would imagine that either of the two hoses nearest the inlet manifold would be OK to connect the crankcase breather to. The one with the big shiny bolt in is probably originally intended for additional breather equipment or possibly an inlet manifold vacuum gauge/econometer.

However, the one furthest to the right should be left unblocked and given a longer length of hose to drape down beside the carb - it is the overflow/vent!
Maurice, Kent.
1970 Trafalgar Blue Traveller

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Hi - thank you the quick reply, I've pulled the cover and we have CAM4810 as the casting number and Big Al's sticky says:

CAM4180 1.0625"/26.99 1.00"/25.4 25.5 998 Mini - A+ (1980-on) and lead free

so not the MG Metro one - wonder why it is red??? It has N D cast on in adjacent to the thermostat and outside the cover and 24AO in bigger letters under it - I was wondering maybe Midget or the like but CAM4180 just keeps coming back to Minis.
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Strange, as I seem to recall most of the 'small block' A-series A+ engines were painted yellow, but maybe some were painted red, either that or someone has since re-painted it for a 'sportier' appearance - you know what those Mini boys are like! :lol:

I do know that the original red paint is very hard to get off; I repainted my red 1275cc Metro 12G940 head in BMC green, and some of that has now flaked off to reveal the original red! Maybe I should just go the whole hog and repaint it red again...

Anyway, good to know you have an unleaded head fitted, and the HIF carbs are far better than the old HS series from the point of view of driveability in traffic (due to the cam-type throttle mechanism) and gererally very reliable and low maintenance.
Maurice, Kent.
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Hi - resurrecting this one as I've been tinkering a bit more - turns out this engine also has the crankcase vent breather fitted (also just venting into the engine bay) - question - given that there is a single vacuum connection on the carb available:

fit a T piece and allow both to run to vacuum through a common feed (and it looks like it's only 6 - 8mm at the carb end)??

or

choose one or the other - but which one?

Thanks
Graeme
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Late (10V) 1098s had the canister attached to the left-hand crankcase/pushrod cover going into a single port on the single 1.25" SU carb, while I gather earlier (1960s) versions used the rocker cover type vent tube.

I would personally go for the tappet/pushrod chest cover version, then you can fit a plain type rocker cover, which just looks neater and makes adjusting the tappets that bit easier.
Maurice, Kent.
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Were there not some that just had a metal pipe from the tappet chest cover, no canister, just pipe bent round and pointing downwards?

Am sure I had one of those on a 1098 in the past!

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Hi - I've popped the tappet chest breather onto the carb vacuum instead of the rocker cover one - unsurprisingly there's no difference to the way the beast runs :D but I think we'll run with this rather than the original setup which was everything just venting into the engine bay.

I do have another question - see brakes section
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Custard wrote:Were there not some that just had a metal pipe from the tappet chest cover, no canister, just pipe bent round and pointing downwards?

Am sure I had one of those on a 1098 in the past!

Sean.


Yes, some (most likely 1960s versions of the 1098cc, which didn't bother with recirculating the crankcase vapours, just vented them to atmosphere) did have this setup, such as depicted below:
Image

Similar to a 1961 MG Midget:
Image
Maurice, Kent.
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Hi - thanks for that - my thoughts were that the vacuum was needed to help stop the crankcase building up pressure and blowing the back 'seal' so was panicking a bit - mind you if I'd stopped and thought about it - the car has been without vacuum on the crankcase for ages and there's no oil leak.......
1955 Split Screen Saloon with later 1098 engine & type 9 gearbox
a rolling r********
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Indeed, the later 10V 1098cc engine probably only had a rudimentary recirculation of crankcase fumes to meet some emission regulation of the time. As long as the crankcase has ventilation of some sort to vent off excess pressure build-up, it will probably work fine.
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You may find the mixture has leaned out a bit as you will be drawing more air/fumes into the carb.
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Had similar problems with 1098 & 1275 engines over the years.
Owen Burton covers the issue in some technical detail in ESM Morris Minors Modification Manual 8th Edition. His recommendations/explanations make good sense to overcome the problem.
The Manual is a mine of information on many modification issues & well worth the few Quid it costs.
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