I've just put a new head on with new head gasket but am only getting compression on 1 & 4.
Around 200 on both which I thought a little bit on the high side.Have I missed something or have a blown a head gasket before even getting it running.

Okay something is wrong and the options arn't happy ones. Provided simple things like the valves opening and closing properly with the correct tappet gap are happening then we start to get serious.

1. The new head - are you sure it doesn't have a crack between 2 and 3 ??

2. The head is not that warped that the head gasket cannot seal it ??? Although commonsense would say that the warp would be greater at each end ie 1 and 4.

3. There must have been a reason you changed the head gasket and the head. Presumably because the head gasket blew and you were losing coolent. Did you drive it a fair distance and did it run dry ???? The reason I ask that is that once the engine runs dry of coolant while its running then the bores suffer and the piston rings glaze and crack.

Its not as easy as just putting in new rings either. The bores wear oval and just new rings doesn't cope and they crack very quickly - like 5 minutes - in the oval bores. It needs to be rebored and new pistons and rings. Fortunatately its just as cheap to buy new pistons with rings fitted as it is to buy the rings alone.

Steps
a. check the tappets and the valve movement first and then test the compression again

b. Get the head checked and skimmed (reco'ed since your going that far)

c. Engine out and gearbox off for a strip down and professional assessment.

Good luck and sorry to be a bad news bearer but you sort of knew this was a possibility anyway ??

The head is a 295 which has been reconditioned, Its got new exhaust values, seats and guides.Its also had a shaved.It hasn't been used since the work has been done.I don't know if it was cracked tested , I didn't ask the person I bought it off that.
Its being used to replace a rather tired 202 head.
The engine had new rings, pistons, bearings and rebore only six months ago.
I have rechecked the tappets but I'll do it again to make sure.

Okay fair enough.

If you remove the rocker gear, give each of the valve stem tops a tap with a hammer. Just a decent tap not a great big whack. You should get a sproing sort of sound. If you get a dull thud then you have a stem seized against a valve guide. This does happen periodically with new guides that are a bit tight from not being properly reamed and not properly lubricated for a startup.

It only needs one valve in 2 and 3 to be slightly open and you lack compression.

See how you go with that. I am now assuming the car has not been boiled dry.

I assume you loosened all the rocker gear off then adjusted it- I've seen people swap heads and not adjust the rockers! You might get away with that on a motor with hydraulic tappets, but never will on a Mini..

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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.

And I think you have hit on what I did wrong.I've whipped the head off and the exhaust valves are bent on 2 & 3.I did loosen the rockers but obviously not enough.
I forget the basic rule of not trying to force something.Live and learn I guess.

Rather than start as new thread.

Now that I have had a good look at it , the valves have bent when hitting the block.Now the exhaust valves are bigger than standard, 1.156 and the head looks like its had a fair bit taken off it , around the 100 thou mark.
With this much taken off it am I still going to have problems with the valves hitting the block. Standard cam and rockers.

I'd say you will need the block notched to clear, with that much off the head. Email me and I'll scan some info to you tonight.

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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.

Probably had that much shaved off to get the chamber size down. The 295 has 28 something cc while the 202 is 22 something. Another way to make up compression when using a 295 head is to use flat top pistons.

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

Whether using a 295 head or a 1275 one, 1.156" valves will hit the block on a smallbore if the head has had enough off it, and the cam has decent lift. I would never fit exhaust valves that big to a 295 head, I turn them down to 27mm. So does GR.

If you must have valves that big use a 1275 head- they have a nice small 21.4cc chamber so hardly any decking is needed, even with dished pistons. I've just finished building one for da Moke (1132cc).

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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.