Thermostat or no thermostat - 1275cc engine?

[bmcecosse]

I was about to suggest the cornflake box.... Serioiusly - get rid of the sandwich plate....

[IslipMinor]

bypass blocked off (standard with the big valve 940 head)

John,

Are you suggesting that all the big valve 12G940 heads had no by-pass fitting? Certainly the MG1300 MkII and 1275 Sprite/Midget had the original by-pass hose with the big valve head, as did the Cooper S. Not sure what else, pre A-Plus, had the bigger valves?

[philthehill]

After reading Islip Minors comment above no doubt he will be agast to learn that I do not have a thermostat fitted in the thermostat housing, no blanking plate or bypass hose (1380cc & 940 head fitted) or even a water pump impellor behind the water pump casing which is only used as a idler pulley for the alternator drive.
What I do have is phospher bronze valve guides so no sticking exhaust or inlet valves. An alloy radiator is fitted at the rear of the car under the boot floor (if there was a boot floor), water is circulated by a DAVIS CRAIG electric water pump which only comes into play when the electronic water pump control allows (so a very quick warm up) There is an extra coolant transfer passage between block and head adjacent to No 4 exhaust valve which was facilitated by MANX Racing. The heater outlet is still retained to take coolent from the rear of the head to the bottom hose. There is a electric fan covering the radiator which I can manually switch on if required. I always keep an eye on the temp gauge and so far I have not experianced any problems what so ever and the engine is not over cooled with all that water which provides additional ballast to the rear end.

[IslipMinor]

Not aghast, but definitely intrigued!

I also have bronze guides and it was the combination of them as part of the unleaded conversion and removing the by-pass hose that started the saga.

Enough of that, can you post some pictures of what sounds like a very interesting installation? What was the reason for the cooling system that you have fitted?

[bmcecosse]

Richard - it was nothing to do with the bypass hose....... it was just a tight guide/valve. You fixed that, and at the same time fitted a bypass - and the problem disappeared.... Many many have eliminated the bypass - and NO ONE else has ever reported the 'nipping' valve syndrom....... All later 940 heads had the bypass connection eliminated - although the big inlet valves were dropped when the heads went 'unleaded' becuase there wasn't enough room for a seat insert on the exhaust valves - although many have since fitted seats to heads with the big valves, and similarly have fitted big valves to unleaded heads....
I like the elctric pump idea Phil - common conversion on the Dolly/Sprint/TR7 engines where the cam driven water pump is a $%£+ing nightmare. So on start up - you have virtually no natural circulation until you switch on the electric pump.......and the exhaust valve manages to cope with that??

[philthehill]

Islip Minor
The reason for fitting the rear mounted radiator was to transfer weight to the rear of the car. There is no point in installing ballast if it cannot be used. Likewise the battery is in the boot and any unnecessary weight removed from the front. Also I would rather have the extra couple of BHP at the flywheel instead of driving the water pump. As you know the main handicap with the Minor is that the engine is in front of the front axle (sic) so the more weight you can transfer to the back of the car the better the car will handle. I cannot move the engine back or carry out any radical modifications as the car would fall foul of the Motor Sport Association (MSA) Mod Prod 1400cc requirements. The car has a MSA log book and is fully compliant with MSA requirements. I will try and take some photographs of the cooling system and post on here. There was a selection of photographs and an article relating to my car in Minor Matters Winter 2002 which you may have seen.

[philthehill]

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Radiator mounted in rear. Electric water pump bottom left of radiator.

[philthehill]

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Water take off from front of engine.

[philthehill]

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Electronic water pump control.

[philthehill]

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Water works at cyl head

[philthehill]

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Pipe work entering cabin.

[philthehill]

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Pipe work exiting cabin.

[philthehill]

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Pipework & plumbed in fire extinguisher

[philthehill]

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view from the drivers seat

[IslipMinor]

[I cannot .... carry out any radical modifications ]

Really? That is quite a cooling system, but not a 'radical modification' of course? Mmm!

What have you done with the suspension and brakes? Do you ever get to a race meeting anywhere near Oxfordshire? I would love to see the car close up?

[bmcecosse]

Does the extra weight of all the pipes/valves/electric pump/fan etc justify the 'advantage' of moving the rad to the boot area??

[IslipMinor]

it was just a tight guide/valve

Can we agree that we will not agree on this.

The A-Series is well-known to be a bit marginal on 'front of engine' cooling, hence the frequent use of the 'blanking plate' instead of a thermostat for competition purposes. If anything, that provided over-cooling, which for competition is beneficial for power, but does nothing for a road car needing a good heater!

Early on in the 2 year saga, the valve to guide clearances were checked by the supplier, who did the unleaded conversion to the big-valve head, and who at the time was reasonably close to home, and were found to be correct. The cause was that the additional local heating, introduced by the lack of by-pass, allowed the clearances to close up enough for one or more exhaust valves to 'nip'. Increasing the local cooling by reinstating the by-pass hose resulted in no more nipping since - that was 5 years or so ago.

All later 940 heads had the bypass connection eliminated

And as you very well know, the sandwich plate was introduced at the same time as removing the original by-pass hose, as part of the revised by-pass system design. BMC/BL never had a production A-Series installation without a by-pass system, which is what your earlier post suggests, and has been suggested many times previously.

You may well get away without one, some do, I didn't, and if anyone is considering making changes that go against the original engineering design, they should be aware of the potential pitfalls.

Minis benefit from being blasted with cool, unheated air with nothing in front of the engine bay to stop it. In-line applications sit is a very cosy environment immediately behind the radiator, with it pouring lovely hot air all over the front of the engine, just when it needs it least. The very last Minis had a front mounted radiator in conjunction with the sandwich plate by-pass.

[bmcecosse]

I have never experienced (or heard of) A series engines being short of front end cooling......quite the opposite - it's the back end that struggles for cooling...... (hence the v common transfer tube from back of head to back of block - using a core plug hole for access) Your engine then is unique Richard - it' s the ONLY engine that has ever had bypass removal overheating... And it doesn't add up anyway - because as soon as there is any heat build up in the front of the head - the thermostat opens! So your guide could not be overheated...... And on a Mini - the 'front' of the engine is very sheltered from the grille air flow.....much more so than RWD applications. But I know I will never convince you - so I'm not going to mention/comment on it again. It's been a fun discussion though!

[philthehill]

BMC
To answer your question as to whether it was worth all the trouble of moving the radiator to the rear - I believe it was.
A Morris is too heavy on the front and too light on the rear. Unfortunately no matter what you do to a Minor with the engine in its original position i.e. forward of the front axle (sic) it is never going to grip like a mid engined (engine located anywhere between the front and rear axle) car even if you have five link suspension fitted. This was admirably demonstrated by Carl Talbot when he took the 300hp plus KAD 16 valve 'A' series engine out of the front of his minor and placed it in a Caterham super seven. Even though Carl put up very good times with the Minor he was not getting the top spot. Changing to the Caterham he went on to win the Midlands Hillclimb Championship up to 1400cc MOD Prod class which was the same as his Minor. Transfering the radiator and battery to the rear was my attempt to even things up a bit. I did not want to put dead ballast in the rear as I believe Nick Mann did with a piece of GWR rail but there again he had plenty of power with that V8; I only have around 130/140bhp at the flywheel. Ballast has to be moved and that weight soaks up power so to get the the best solution I could I moved the radiator and battery to the rear. That is what I would call active ballast as it does not just sit there and do nothing as i.e. a piece of rail would do. So I have lost the Minor radiator weight plus water (at 10lbs/gallon) at the front of the car, the water pipes are mostly behind the front axle. The precise location of the radiator in the 'boot' was determined so as to balance the weight across the rear of the car so that as near as possible identical weights are pressing on the rear springs. The drivers weight was also taken into consideration when trying to get the right balance.
The car is well balanced and can be thrown around at will so I must be doing something right! It has always drawn a crowd in the paddock after a run and the numerous comments like "my grannie had one like that but hers never went that fast" always puts a smile on my face.

[bmcecosse]

Oh yes -I totally agree about needing weight in the rear, and less up front. I did the exact opposite with my track Mini - moved just about everything up front (fuel and battery) and moved the seat as far forward as possible (even with my 6'2" height...) and eliminated the rear subframe and the boot floor..... I could pick the rear up and wheel it along like a barrow.....