Morris Minor Owners Club

Hi all,
Mogs went out in a cloud of steam this weekend having blown the head gasket.

On the very up side this provides me with the chance to fit my 1275 head. I will be running it with standard 1098 manifold, exhaust and hs2 for the time being.

Can anyone running a similar setup suggest what needle I should run in the carb?

No idea! You really will need the larger 1.5" carb - and then it's generally AAU or AAA needle. Be sure to check exhaust valve clearances from the block with that head - and 1275 rocker gear, and gasket of course........

I have got my eyes out for a cheap hif carb, I don't suppose I will find anything to add to the set up until beaulieu.

I sat the head on the surface table and measured .295" of available lift with a dial indicator on the valve stem, the head gasket measures .048" before compression and not of the copper type

I think I will be grinding those valves until my hands are bloody, I wouldn't want to guess how much the gasket will squish.

Forget the gasket thickness - that's your safety margin... The valves NEED 320 thou between valve head and head surface. 10 minutes with a slow revolving 45 degree countersink in a pillar drill does the job nicely. Hand lapping will only increase the clearance by about 2 thou at best.........

I'm not sure how you measured that valve lift on the flat surface but the 0.295" equates to 7.493mm which is not enough. You really need to measure the depth from the valve face to the head surface. Cheap digital tyre depth gauges available on ebay for a little over a fiver can be used. I would use a valve seat cutter with the correct pilot to sink the valve to 8mm before a final lapping is done.
Regards
Declan[frame][/frame][frame][/frame]

Declan, I measured the clearance in much the same way as yourself except instead of a scrap of ally and a vernier I used a surface table and a dial indicator.

I didn't realise the measurement is from the head face, I thought it was the minimum from the block with a gasket fitted ... oops. Knowing this I think I will scrap the plan, I don't have hundreds of £££ to spend on a valve seat cutter. I think I could pick up a complete 1275 engine for only a bit more.

Anyone want to purchase a 1275 940 cylinder head?

Thinking on it ... what angle is the valve seat? I can make a cutter for next to nothing!

I don't have hundreds of £££ to spend on a valve seat cutter.

This one is cheap enough and looks more comprehensive than the one I use.
http://www.ebay.co.uk/itm/Valve-Seat-Cu ... 20d538a665

Eth,
It's easy enough. Measure it again-some get away without sinking the valves. See if you can borrow a 45°valve seat cutter for a couple of hours. The one I have was from ebay and wasn't that expensive. I think the postage was more than the cutter. The one Marky has found is identical to mine.

Regards
Declan

A simple 45 degree countersink in a pillar drill does the job nicely - and is certainly not going to be 'hundreds' of pounds. It self centres and just cut down the amount you require. 10 minutes easily did all 4 of mine. And if you plan a 1275 engine - better hang on to the 1275 head!

A simple 45 degree countersink

Rather a big one surely?
My countersinks are all about screw head size.

I prefer the valve cutter with the pilot as there is less risk of chatter.
Declan

Of course Declan - and yes a BIG 45 degree countersink. There was no chatter Declan - the tool maker placed a piece of emery cloth over the seat and the cutter (revolving slowly) took that round with it. The seats were absolutely perfect - I was frankly amazed! Only the very lightest of hand grinding was needed. A set of seat cutters is very nice to have - but how often does the 'home mechanic' need them....?

Why don't you get your local engine shop to do it? Shouldn't be more than £20.

And £115 for that set of cutters.......geeezzzzzzzzzzz

Well in the end the easiest (very easy), fastest (5 mins) and cheapest (free) way to increase the valve clearance was to turn some metal from the flat face of the valves.

Job done!

My head has never been skimmed, after lapping and cleaning .010" was the most I had to remove.

Some may call it bad practice, I call it performance lightened valves.

Plus it must be better than pocketing the valves. Valves are readily available for butchery, good condition cylinder heads must be becoming rarer. Many good reasons to follow suit if the clearance gain required is quite small.

I have got an aaq needle for the carb, I will report back with findings it may be a waste if time but I will give it a try

10 thou won't do the valve heads any harm...... as long as you have that 320 thou - it will be fine.

.322 for good measure I cant say its made much improvement in acceleration at the moment but im sure I am using less throttle for the same speed and seems to cruise easier at speed. Now looking forward to upgrading the exhaust and induction

It won't - until you increase the carb size. be SURE to retorque the head (44 ft lbf) after the first heat cycle.

Agree completetly with above, once the carb is changed, you should notice a fairly substantial increase.

For reference, my old Mini with 998, standard rubbish head but the "stage one" upgrade (k&n, free flow exhaust, alloy inlet) felt ok when i got it. Once i fitted the AAA needle though, different beast all together!
Just goes to show what a lack of fuel can do, so i look forward to your findings once the bigger carb is put on