Just wanted to share work I have had done on 295 head which cheap valve let go on. I can't express enough don't buy none race valves if you are planning on running large cam and double or high compression valve springs. I was told the original valves I bought would be ok which was bad advice which has now cost me a complete rebuild. I have had the head with Graham Russell for some time and got it back today and all is looking good, Graham said he would look after me with this PITA broken valve episode I have had and he did. To make situation worse the head shop I had do the valves in last sunk the seats so much lower then they needed to be it almost binned the head but GR has fitted the new small bore race exhaust valves with seat inserts and gone a bit custom on the inlet to extend more life out of the head.

See pics below of head when valve let go,



Pics of head with all the good bits, I asked GR to fit single valve springs in to get me to 6500rpm only as I have no intention of going higher then that with 1100 crank. I think the double valve springs commonly used at 200pounds are far to strong but many people use them so seems maybe just my opinion but I am happy with the force of these singles now on the head.

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1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

Looking at your pictures there was more stuff wrong than just a valve failure....

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67 Deluxe
Dry suspension
1293cc, 11:1 comp, RE 282 camshaft, 45 Weber, extractors etc
4 synchro close ratio gbox
Cooper S brakes, no booster
Stealth box, as Doc says "goes harder and idles!"
RH tank cos I needed it crossing the Nullarbor etc..

How do you mean?


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1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

maybe the oily soot in the next chamber and the rusty gunk in the water jacket?

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did I tell you that I won a trophy?

When the valve dropped and punched hole in piston pulled oil into number 2 through inlet manifold. It actually pulled pieces of the smashed valve guide in to number 2 as well.

I shut it down and put clutch in as quick as I could but happened very quickly!


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1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

same thing happened to me a few years ago - my MK2 head looks a lot like yours did, maybe a little worse... we reckon the valve seat insert dropped out and stuck the valve open

I should get GR to have a go at it

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did I tell you that I won a trophy?

I have a 1275 head that did the same, it totalled the insert and beat up the chamber and inlet seat. I welded the insert recess right up with nickel electrode, GR is going to machine it for one of his inserts which are smaller OD.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Is seat inserts falling out a reason for not converting a head to unleaded? How common is this on converted heads?

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Slide
1965 Mini Van (1360)
1970 Mk2 Cooper S (1310)
1978 Rover SD1 V8 (4.6)
1996 Land Rover Discovery V8 (4.0)

dunno how common it is, but I don't think it's a reason not to have it done, I think it's a reason to make sure they're done by someone who knows what they're doing and that your car is running right.

Mine happened on the first long drive after I'd put a supercharger on my motor and I think it was running much too lean, to the point where heat expansion in the head & seat were too different and the seats loosened. The other seats show similar signs of not wanting to stay put. It could also be that the bloke who cut the seats for the inserts made them a bit too big with not enough interference fit, dunno at this point. My current head went on to the next build of the supercharged motor without seat inserts, then when I rebuilt it the seats were rooted so I had inserts put in. I had the head off a few months ago and they looked fine

My dad's 1275 Minor has had exhaust seats in it since the early 90's...

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did I tell you that I won a trophy?