Morris Minor Owners Club

Hi all,

Have test fitted my marina 12g940 today onto my 1098 (standard cam, marina rocker gear). I bolted it on the block with no gasket, set the rocker clearance to 0 and, gritting my teeth, turned slowly by hand.

When I removed the head, the valves had indeed cleared the block and by the thickness of compressed gunge under the exhausts, I reckon just cleared it by about 3 thou.

The gasket I took off measured 39 thou (about a mm), so I guess my new one will compress to the same thickness.

My question - do you think this will give enough clearance to run OK at normal running speeds / temperatures (will set rocker clearances to 15 thou)?

Many thanks

Russ

Yes - sounds like you have one that makes the clearance ok! Just check the cylinder head wasn't sitting on the water pump ? It usually needs a pass or two with a hand file to get clearance between pump and head. But - assuming that's ok - you should be fine !

hi did you have to do any mods ive a nice midget 1275 head which i would like to fit to my spare 1098 engine

Hi,

the only 2 mods I had to do were to reverse my heater valve (sits at the far end of the head) by 180 degrees, and also grind a notch in my engine steady bar to clear the base of the aforementioned valve. Nothing more to press, but I'm not finished yet! Other contributors will be able to give you lots of advice I'm sure.

All the best,

Russ

PS - BMC: thanks. Will check the water pump tomorrow.

Xero - you just need to check this clearance - i've not been this lucky and I had to sink my exhaust valves into the head by 40 thou to get safe clearance. Use a 1275 head gasket - and use the 1275 rockers or spend time re-aligning the origional rockers on the shaft so they act directly over the exhaust valve tips. If the head has no bypass hose connection - then either block the hole in the water pump, or fit a no-bypass water pump.

Hi all,

Xero: work all finished now, no more mods were necessary. I was getting some viscious misfiring (coming back up the carb), and the car was very slow but have altered the timing a considerable way on the distributor vernier to make it run OK....the timing mark is now miles away from its original spot, it now looks like it's about 20 degrees advanced!! There will be more to do here before things are spot on I feel...

Cheers,

Russ

PS: have ordered 1.5 inch exhaust system, I couldnt resist. No self restraint at all!

sowden wrote:Hi,

the only 2 mods I had to do were to reverse my heater valve (sits at the far end of the head) by 180 degrees, and also grind a notch in my engine steady bar to clear the base of the aforementioned valve.
All the best,

Russ

Hi Russ I understand the notching in the steady bar as its quite common but reversing the heater valve is a new one on me I know it can get close to the battery tray but how does the valve still operate the wrong way round as normally if its clearance is a real problem the earlier type gate valve is used.

had something of the same when installing the 1275 as i like heat i just cut the tap of and fitted the hose lower down on head if you get what i mean happy days no damaged knuckles trying to get the nuts done up

Kevin, will post a photo when I can get out and take one. Basically there seemed to be more clearance one way than the other, so I switched it round. Have not tried to adjust the heat yet though, it might all go bad at that point!

The car is running horribly since I did the swap, actually; I'm fed up! I'm going to switch the carburation back to original to see how much difference it makes, but basically I've had to advance the timing massively to get it to run anything like normal, and of course it's pinking for England. When I retard, the performance turns to custard (and its not that brilliant even 'on song'!).

And my new brakes are pulling to one side!!

(I wont bore you with my boat resto problems!!!)


Wishing I was in the Caribbean,

Russ

Are the valve gaps set correctly ? Set to 12 thou inlets and 15 thou exhausts. It should be running very much better with a 940 head - assuming it's in good condition and the valves were all nicely ground in! Don't understand the need to advance the timing - and you must NOT allow it to pink. May be wise to try the top grade petrol - the compression ratio will be slightly raised - in theory the timing should be slightly retarded! What carb/manifold is on there now - and what needle in the carb - and what air filter? Try running with NO air filter and see if that makes a difference. Do you have the vacuum advance connected up to the dizzy ok ? Check the vacuum pipe connection on the manifold is not blocked.

Hi BMC,

valve gaps OK, head was given a mild overhaul by myself and valves are lapped in OK. Just ran like a badly set up example at standard timing, but was better when more advanced. Carb is a HS4 with new AAA needle (which I have to say, seemed not to fit in the orifice perfectly well...seemed a bit small.). K&N type cone filter. vac advance connect OK; assumed not blocked but would need to check.

Swapped the carb today for another HS4, which seemed to run OK for about 20 seconds and then the car started running on 3 cylinders (or thats how it seemed - really rough with heavy vibration - like a dumper truck!). The last straw was going to do a compression test and the battery failed before I could do the final cylinder!!! It seems knackered too, I think I will need to buy a new one.

I had to smile at that point, and asked God to be kind to me the next time. Meanwhile, its the peasant carrier for me tomorrow!

Hmm - don't like the sound of that 3 cylinder description . The AAA is designed to be used with a swing needle carb - I think should be ok in the HS4 ? HS4 should have a 90 thou jet - but just possible someone has fitted a 100 thou jet - although why they would do that is anyone's guess! I assume you did use a 1275 head gasket ?
If your brakes are pulling - you must have a stiff/stuck (hopefully not leaking!) cylinder. Worth taking the leading edges off the shoes too. Don't ignore the rear brakes- if one side is stuck that too will 'pull' the car on braking, or though not so violently as a stuck front brake !

Hi,

have been trying to chase down the problem today. Have done the compression test, all about 150/160, so no problems there.

When I went to time it up, the strobe didnt fire all the time (my strobe takes its pulse from a magnet round one of the plug leads) - so I believe it is an electrical problem now.

Symptoms: coil gets hot; battery flattens quickly (put a brand new one on at 11.00 this morning - its flat now (3.00pm), and I've not been unduly cranking the engine. Intermittent spark (number 1 cylinder seems the most affected).

Have removed distributor, replaced points, condenser, distributor cap and rotor arm, and swapped an old (previously working) coil - no change. The distributor has no wear in the spindle, spins OK, and opens and shuts the points OK. The vac advance works.

When I'd finished all the distributor work, the car didnt sound like it was running on 3 cylinders anymore....it sounded like there was uneven supply of sparks; very hesitant, like it wanted to go but was not getting the electrical juice.

Any advice gratefully received, I'm feeling very defeated by it at the mo!

Cheers,

Russ

You haven't mentioned anything about swapping plug leads - that may be worth a try. Also, the symptoms you describe most recently (lack of power/rough running, rather than intermittent firing of the strobe) could be caused by a sticking piston in the carb (assuming an SU). Take the air filter off and check that the piston moves freely. If the distributor drive gear was put in at the wrong angle then the distributor itself will be a long way out from where you would expect it, which could be why you are finding the need to apparently advance the ignition a long way.

The flattening battery must be a short to earth somewhere, which could of course be affecting the spark. Inside the distributor, check that the low tension wire from the terminal on the side to the points hasn't lost its insulation, o perphaps its caught on between the moving and fixed plates?

One way to check how the leads are performing is to have a look under the bonnet with the engine running in the dark.
If you can see any sparking the leads are shot.
Also you could put a blob of paint on the crankshaft pulley then attach you timing light to each lead in turn to see if one is playing up.
If you put the timing light on the lead from the coil you see if the coil is firing every time as you should see the blob in 4 different positions.

Battery going flat surely indicates lack of charging! Seems you have changed most of the ignition parts - that 'low tension wire' suggested earlier is certainly worth investigation. Could also be loose connection - try a direct feed to the coil from the battery to see if it's ok then. And also - try a wire from the coil (CB or -ve terminal) direct to the dizzy. double check the spark plug leads haven't been mixed up - must read 1342 anticlockwise round the dizzy cap.

And check the actual coil terminals are not loose where they rivet into the coil top- that one caught me out, especially when fiddling with leads would make things better for a bit, or worse, depending how much I had wiggled the terminals! And the earth wire in the distributor can come adrift yet still look good... Bet its nothing to do with the new head- just sods law coming into play again!

Yes,good point - I've had the loose coil rivets too!

Hi all,

finally got to the bottom of my woes.

I think the initial poor running was down to bad set up and a cold engine. I faffed with the distributor and made it worse as I put it back together wrong. Thats fixed now. The car seems to run better slightly advanced but I'll see how this goes. I've piped up the inlet manifold just to give it a fighting chance in this cold weather.

The flat battery was due to my favorite trick of leaving the heated rear screen on. What a twerp! Just goes to show that first principles should always be adhered to....rule out the obvious first. That mistake has cost me £40 on a battery I didnt need....

Here are some picks - Kevin, notice the reversed heater valve. The brass bit is to stop the battery cutting into the pipe (which it did during my test drives).

My next move is to fit the 1.5 inch exhaust and get the car tuned. Then the 3.7 diff goes in....and the work is finished.

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Instead of that hassle with the heater valve - just invest in a little stub pipe as was fitted on later Minis etc. You don't want to be closing that valve anyway - not even in summer!