Rusty thermostat/water pump bypass

[philthehill]

As I said above the limiting factor in skimming an 'A' Series head is the oil way feeding the rocker shaft and which runs across the bottom of the head.
There must be a minimum of 0.040" of metal between the face of the head and the O.D. of the oil way.

If the additional skimming breaks into the oil way it can be repaired but it would be cheaper to purchase a new head.

[jimmy-d]

Its a head of an engine that I have no history on so considered firstly that it was a good move rather than fit then find and issue and secondly because I was thinking of putting it on a 950 engine so believe it needs skimming in standard form to bring the comp to a suitable level,the head is originally off a low comp 1098. I do still have the head on the 950 so may just pull it to check it out,otherwise I have a Datsun 1200 engine complete,I could use this but here in Aus that means I would have to get the car engineered and approved with other required alterations,dual circuit brakes,collapsible steering column,seat belts etc which adds cost to the project plus about 800-1000 $$ for the engineering assessment which is $$ that could be better spent initially.

[philthehill]

Just a note to say that the compression ratio is effected by the dish in the piston i.e. High compression pistons have no dish or even in the case of the 998cc Cooper raised 'D' shaped crowns and low compression engines can have varied sized dishes dependent upon compression requirements.
The combustion chamber remains the same size throughout the head casting number and therefore has no variable effect on compression ratios.
Of course if the head is skimmed it becomes non standard and that does indeed effect compression ratios.

[jimmy-d]

So I have pulled the head of the 950 to check it out and replace the by pass and it is for all intensive purposes,from what I can see original and no skim previously done as measures 2.75 close enough. As the head of the 1098 was 2.684 is there anything left in it to skim or should I just take the chance and fit on the 950. I want the 950 to have a bit more poke and the 1098 has larger valves,or should I just get the 1098 inlet valves fitted into the 950 head,if this is possible and I will swap in the cam from the 1098 also, I want to remain with the original engine currently for rego reasons to avoid engineering costs etc.I also have a twin card manifold so considering twin 1 1/4 SU carbs and extractors with 1 1/2 exhaust. I am aware of the Vizard book but am not looking to spend large money on an A series as it will get changed eventually.Also,how do you identify a head,I assume the 1098 head is a 12g202 (?) but this number is not present on my,the head I took of my 1098 says 2A629 and it has larger valves than the head from my 950,the head from the 950 has no part number,it does not even say MOWOG like the other head,the only ID is an embossed B and ECAM4004,I am easily confused so is it a 950 morris head or what??

[jimmy-d]

These pics are of the head from the 950,to my way of thinking,the valve gear also looks different,anyway,definitely different to the gear on the 1098 head.

[philthehill]

The head is not Minor - most probably off a late classic Mini (possibly Pt No: 12A1451/CAM4005) and could be unleaded.
The rockers are not Minor either but are sintered steel instead of pressed steel and are from a late 'A' Series engine again probably off a late classic Mini.
Could you please post a photo of the spark plug side of the head and combustion chamber.

[jimmy-d]

Pics as requested.

[don58van]

Unless I am very much mistaken... that is a late head, with anti-pollution passages visible below the spark plugs. Possibly from the USA.

Don

[jimmy-d]

Hi Don,are you suggesting late Minor or late Mini? As stated above,there is no Morris type ID on it like MOWOG or similiar and the ID embossed in the valve area does not appear to relate to anything Minor that I have yet found.

[don58van]

Definitely not from a Minor -- from a Mini.

Don

[philthehill]

Thank you for posting the photos.
The photos confirm that The head is the anti-pollution head from a late export Mini (998cc - 'A' Plus - year 1981 on) and is part number 12A1451/CAM4005 with head casting number CAM4004. It should be noted that BMC/BL castings/forgings are always one number difference.
The head can be used without the pollution equipment but the air injection holes need to be sealed.

Below is a photo of a 'A' Series fitted with the air pollution equipment.

[jimmy-d]

Thanks for all the input,the pollution holes were blocked with cut down bolts. Is there any benefit to using this head over any other available head ? Could anyone advise regards my 1098 head,it measures 2.684 so is there anything left to skim or has it reached its full extent. Again,thanks everyone,much appreciated.

[philthehill]

There is no real benefit in using the CAM4005 head over a 1098cc head.

As regards the already skimmed 1098cc head:-

Measure down (from the head top surface) the oil feed vertical gallery feeding the rocker shaft and subtract that measurement from your 2.684 and see what you have left.
You must have at least 0.040" difference otherwise you will break into the horizontal oil gallery when skimming.
The head can be repaired if the oil gallery is broken into but it is not economical to repair - just obtain a good S/H head.

[jimmy-d]

Hi again,did a depth measurement down the feeder hole for oil to the rocker assembly,measured 2.636,so based on the external measurement of 2.684,that leaves .048 to my reckoning. What is the max skim I might need to ensure the head surface is flat before refitting,could I possibly get away with a sub .008 skim to maintain the .040 clearance needed for the oil gallery? When I removed this head there appeared to be no issue apparent with the gasket or head/block surface so maybe I should just refit and see what happens,opinions again please and thanks for all the other help. Regards Pete

[philthehill]

I would not skim again but refit the head.