Oddball engine. 1098 or 948?

[RobThomas]

Nick, up the road, has bought an engine. Now, it is clearly a small bore jobbie because of the side covers but there is no engine number on it and no plate on the left/front with the capacity on it. The 12A497 casting number is the generic one for the 948 and 1098 so that doesn't help. It has a Metro timing cover and harmonic damper, a Marina sump and a 12G202 head, although none of these things tells me anything. The crank tail has the original 4 bolts, has 2 dowels added along with 2 more threaded holes that are an odd number of degrees removed from the other holes. Not an FJ crank, not a Midget 10CC series crank with the big journals and not a 1275 crank. So, is there any way of telling a 1098 from a 948 from the height of the block from sump line to the top of the block? I could dismantle the head to pop a pushrod out but I'm not sure that would tell me anything for certain. Also, are the crank tails visually different between them? Too heavy and messy to lift it out of the box to pull it apart from below.

Thanks, on behalf of Nick.

Rob




PS. The only question I need answering is whether there is a block height difference between 948 and 1098 and if there is a visual difference between crank tails, before anyone starts (you know who I mean).

[philthehill]

A photo of the rear of the crankshaft would be appreciated.
It could be any variation of parts as a 1275cc Midget crankshaft can be fitted into a 10CC engine as can a 1275cc Marina crankshaft.
Over the years there has been with a bit of machining of either the 948cc and 1098cc blocks the ability to mix and match crankshafts.
It could be that the rear of the crankshaft has been drilled and additional studs fitted to accept a different flywheel.
The 10CC flywheel will not fit a 10CG crankshaft as the PCD of the 4 flywheel bolts is larger.
The tails of a 948cc crankshaft and 1098cc crankshaft are the same and that is why the flywheels are interchangeable.
The height of a standard 948cc block is 218mm - that is from the sump flange face to the top of the block.
On comparing the strokes of the 948cc (76.2mm) and the 1098cc (83.72mm) engines if a simple assumption is made that the clearance above the piston at TDC is the same the calculation to determine the height of a 1098cc engine block will be:-

83.72mm minus 76.20mm = 7.52mm divide by 2 = 3.76mm plus 76.2mm = 221.76mm.

The simple height of the 1098cc block will be 221.76mm.

[RobThomas]

Thanks, Phil. Got all that.

I should at least be able to measure the block next week.

[daveyl]

The 948 engine has '950' cast into the block. It's located at the front on the tappet chest side. If it's there, you can't miss it.

[RobThomas]

Not on a 12A497 block casting. Only on the earlier ones.

[philthehill]

Rob
You say that it has a Marina sump - the Marina sump has a flat plate attached to the bottom that fixes to the Marina bell housing where as the 948cc/1098cc and 1275cc non Marina in line engines do not.
Could the Marina sump be a red herring in that the block is just resting on it because the original sump was not available.

[RobThomas]

It is a built-up and running engine so I was not expecting to see the extra plate that goes beneath the Marina gearbox. The Main caps shouldn't fit properly so I'd like to know how that sump has gone on, unless that engine has been somehow adapted to fit a Marina gearbox. Question then would be...why??????

Shame I couldn't get it out of the box for a better look. Next week, if I'm out of the Hospital, I'll drop by and get some pics.

Found this pic on the interweb. maybe this explains the extra oddly-positioned holes and dowels? Looks similar. Do the 1098/948 cranks take dowels or are the 4-bolt drive only? I know the Vedette 948m has a dowel on it.
[frame][/frame]

[RobThomas]

12G432 was the 1098 with the big crank, IIRC.

Vedette 950. Different again.[frame][/frame]

[philthehill]

Rob
The flywheel posted above appears to be a lightened (and modified for a 7.5" clutch) 1275cc Midget/Sprite flywheel.

If you count the holes there are 6 bolt holes and two dowel holes - same as the 1275cc Midget/Sprite.

I suspect that the engine block in question is a 1098cc fitted with a 1275cc crankshaft which is perfectly feasible with a bit of machining and has had new 1275cc front, centre and rear main caps which would allow the fitting of a 1275cc crankshaft and 1275cc sump.

The standard 948cc/1098cc crankshaft including the 10CC prefixed engines only had the 4 bolts and no dowels.

There is an article in Car & Car Conversions February 1968 featuring a Autocross Morris Minor Reg No: TYV 961 (is it still around?) which was constructed and driven by Brian Moorcroft.
Interestingly the modified 1098cc engine had the crankcase machined to take the nitrited 1275cc Sprite crankshaft. The three main bearing caps were replaced with special steel versions, the flywheel was lightened and the whole balanced.
Lots of other engine mods listed but the main point is the use of the 1275cc crankshaft.
The capacity of the engine in the autocross Minor was 1150cc.

[RobThomas]

Thanks, Phil.

That makes sense. It will be interesting to open that engine up if the opportunity arises. I think he paid about £80 for it on Ebay last week. He'll be very happy!

Shorter stroke on a 1275, isn't it? Should be about 1050cc, although I may well be wrong?

https://www.mikehaywardcollection.com/m ... minor.html

[philthehill]

Rob
The stroke of a 1098cc Minor is 83.72mm whilst the 1275cc Sprite/Midget is 81.28mm - so a little shorter by 2.44mm
As the engine fitted to Brian Moorcroft's Minor was a special one off the pistons used and the bore size is unknown and not stated in the Car and Car Conversion article.

Many thanks for the link to the photo.

[RobThomas]

[frame][/frame][frame][/frame]

Nick got some photos for me.

Thick flange generic small-bore block. 4-bolt converted to 6 bolt and 2 dowel.

[philthehill]

Rob
Many thanks for posting the photos.
I cannot make out as to whether the flywheel flange is parallel for and aft or does it have a taper register.
First photo is of a 1275cc 'A' plus Marina/Ital crankshaft with its parallel tail.[frame][/frame]
The second is a 1275cc Midget/Sprite crankshaft tail with the tapered register.[frame][/frame]

[RobThomas]

It's parallel and is a lot thicker fore-aft than the 950 cranks I've got here. The spigot bush in it was bronze rather than needle roller.
Starting to really look like a 1275 hiding inside a 1098 block, isn't it. I'm itching to have a look inside when he cracks it open. How on earth do A+ 1275 rods clear the 1098 crankcase or are the blocks all the same clearance internally? I guess it would make sense if they are.

[philthehill]

If it is parallel it could be a 1275cc Marina/Ital crank or even a modified Maestro crankshaft.
To enable large bore con rod big ends to move round without fouling the crankcase the inside of the crankcase is relieved.

[Matt]

Finger in the air...

Could it be a 1098 from an early marina commercial?

[philthehill]

Matt
I think that you have hit the nail on the head.
10V engine Pt No: 38G528.
The sump Pt No: 12G3150 is listed as having the connecting plate.
The connecting rods are the same as those fitted to the 1098cc Minor engine Pt Nos: 12G126 & 12G123.
The rear end of the crankshaft / flywheel appears to be the same in the Marina parts list but there is a tendency within the parts list to use the same diagram irrespective of the engine size.

[RobThomas]

I'd never heard of a 1098 Marina before. Any idea what gearbox went onto it? I presume a ribcase rather than the later Marina box from the Triumph?
Hopefully Nick will be home tomorrow and I can have a go at opening the sump up.

Google doesn't seem to show much info on 1098 Marinas.

[philthehill]

Rob
Looking at the BL Marina parts list the bell housing is the same for the 1098cc 10V engine and the 1275cc 12V engines.
The gearbox (Marina/Triumph type) Pt No: 38G548N is the same for the 10V and 12V engines. There was an earlier gearbox Pt No: BHM5006N (listed as NLA).

The crankshaft when fitted to the Marina 10V engine had the following Pt No: 8G2745 (with bearings).
The first motion shaft is listed as bush (not needle roller as per the 12V engine) Pt No: 13H4653.
The flywheel assy fitted to the Marina 10v engine is Pt No: 22G2232.

This is the link to the BL Marina parts list - well worth the £10 plus postage.
http://www.ebay.co.uk/itm/NEW-MORRIS-MA ... qVmipG2TFg

[RobThomas]

Thanks for that, Phil.

Once again, useful info with part numbers, references and sources.