Please measure your 948.

[RogerRust]

I am about to re fit my 948 engine that now has a 1300 cylinder head fitted. The cylinder head is about 10mm longer.

What I'm after is the clearance between the heater tap and the battery shelf with a standard cylinder head. It has the old screw tap type of valve fitted.

thanks, Roger.

[patgarrett]

Hi I didn't think the 1300 head fitted the smaller block A series engines(948/1098) without mods to the block. Have you had these done and if so what was done? Sorry can't help with the clearance as my moggie has a cable type valve but will measure if it's any help.

[RogerRust]

Yep I've done all the mods and fitted the 1098 cam as well!!

[bmcecosse]

The valve will be VERY close to both the tray and the battery - I found I could only get room for the little early brass manual valve - the one with the little lever. On the same subject - have you checked the water pump is not fouling the cylinder head at the front of the engine ? I had to attack the pump with a hand file to get some clearance.

[Roni]

I have just replaced the heater tap, finally, on mine. It didn't go according to the book. The problem for me was the 1300 head heater take off was at an angle and this turned the cable type valve far enough to hit the battery. I got around this by lifting the valve on an adaptor that also gives me turn adjustment to turn the valve back to its correct angle.

I also had to do the water pump mod too when the head originally went on.

[bmcecosse]

That's neat Roni!! Maybe you could sell the bits for this to others. The same problem occurs when fitting the complete 1275 engine - not just when fitting the head to small bore engines.

[RogerRust]

ok next problem!
The head fouls the 948 back plate.

[bmcecosse]

Hmm - not a problem for me with the 1098 engine. Attack head and/or backplate with file !! Just to check RR - did you sink the exhaust valves into the head by 40 thou ?

[Roni]

It is good to have a container full of useful bits.
The heater adaptor was made from a couple of old brass heater tap bases and a pipe fitting from the local friendly plumber shop. The bases are available new, in alloy, from one of your many good suppliers of Morris Minor parts.

[RogerRust]

One of the valve seats was damaged so we took about 50 thou out of the seats so the valves should be well clear.

I have a 1098 back plate.
Will my 948 gearbox fit on the 1098 backplate?
With the thicker backplate will I have a problem with the gear box moving back a bit?
What about the gearbox spiggot and bendix on the starter?

I might sell my 12G940 and look for a 12G295

[bmcecosse]

I think really the engine will move forwards - but the difference must be very little ? The 940 is by far the better head -stick with it. And 295 heads are quite expensive , and 940 heads seem to sell on ebay for very little these days. I would stick with the backplate you have - and just take a little metal off the top edge with a file - or an angle grinder!

[chrisd87]

If the starter and gearbox don't line up correctly you could always buy a cheap 948 engine and rob the backplate off it. They seem to go for very little money on ebay as I assume everyone wants the 1098s and 1275s.

[RogerRust]

Ok job done.

Starter motor off
Gearbox off
Clutch off
flywheel off
Backplate off - cut top off Pictures to follow
Dynamo off
Water pump off - filed to give clearance
water pump on
Dynamo on
Backplate on
Fly wheel on
Clutch on
Gearbox on
Starter motor on

Now the head fits!

3 1/2 hours - time for a cuppa tea.

before


After





my heater valve is a bit like this one, only mine is a taller I hope I won't have to do anything more that notch the front of the battery shelf.

[bmcecosse]

WOW!! I would just have cut the errant backplate in situ - and i did just file my water pump in place. Your engine looks superb - lovely job. I assume you are going to use a 1275 head gasket (you MUST!) - and if you don't have the 1275 rocker gear then you need to re-align the rockers on the old rocker gear so they will sit nice and squarely over the exhaust valve stem tips.

[RogerRust]

I cut it with a 1mm cutting disc. I never use a hack saw now it is so much quicker and more precise. I think the dust would have gone everywhere and I didn't want to take the risk.

I have got a set of 1300 rockers, but they don't line up very well either. I can line some of them up by adding packing washers, but it looks like I will have to do a bit of heavy duty filing on one of the pillars.
I haven't checked yet but I seem to remember that there are oil ways in the rocker shaft I just hope they don't get exposed.

If I'm really stuck can I bend the pressed steel ones a little bit?

What I plan to do is clean and strip the 3 sets I have and mix and match to make a good one.

[alex_holden]

There should be an oil hole in the shaft at each rocker position. Perhaps you need to get a 1275 shaft so the holes are in the right places? I wouldn't recommend bending the arms as the forces will then be off-centre and the bushes will wear unevenly.

[patgarrett]

Hi, sorry to highjack your thred but you all seem to know what you are doing or have done this before, could you please tell me what I would have to do to fit a 12g940 head on my 1098 engine and what differance it would make. Many thanks Pat.

[bmcecosse]

RR - the later engines all used the same 'fat' sintered rocker arms - and these just straddle across the different pitching of the exhaust valves. This is obviously not ideal engineering wise - and no use on a competition engine - but is reasonabaly trouble free for road cars. Some re-alignement with washers and a little filing (of the arms - not usually the pillars) is all I do - and I never use the sintered rockers - always the pressed steel ones - although I do have proper 'cast' ones on my Mini S engine. DO NOT attempt to bend the pressed steel ones - just shuffle them along with washers and filing. It's quite satisfying to get them properly lined up - and doesn't take that long. Just make sure the shaft ends up the right way round - with the oil hole above the rocker pillar with the drilling to bring the oil up from the head into the shaft - and the little lock screw fitted into the locking hole.
Pat - you need to sink the exhaust valves into the head by 40 thou - and then follow this thread. It's an excellent 'stage 4' head for a 948 engine, or a 'stage 3' head for a 1098. With a larger carburettor on a good alloy inlet manifold (and ideally but not essentially a better exhaust) it makes a very considerable difference to the engine. Better still - as RR has done - with the better AEA 630 camshaft (standard in the 1098) fitted into his 948 engine.

[Kevin]

That's neat Roni!! Maybe you could sell the bits for this to others. The same problem occurs when fitting the complete 1275 engine - not just when fitting the head to small bore engines.

One of the Moggis specialist internet suppliers sell just what you need to do this.
Roger until you pop the engine back in place you wont know if you have clearance or not due I think to old fashioned manufacturing tolerances, my old saloon with the midget engine had no clearance problem with the gate type of valve fitted and I have seen the later valves occasionally fitted without adjustment to the battery tray as well.

[patgarrett]

Pat - you need to sink the exhaust valves into the head by 40 thou - and then follow this thread.

Thanks sounds simple enough I will have a go when I can get hold of a 12G940 head.