1275 block - 1098 head?

[catsoup]

Hi,

Im now the proud new owner of a Marina 1275 engine. This is to replace my 1098 whose block developed a crack.

I dont want to replace the engine for performance reasons, I have a twin cam project for that! I only want to modify this one within these limits:

1. Keep the cost to a minimum
2. Get rid of that darn dripping oil from the rear main scroll seal. (I belive the marina has a proper seal there?)
3. Maintain a reliable day-to-day car.
4. Keep mpg reasonable.

Bull motif has quoted me £324 for the modified flywheel, backplate and exhaust system. And I will still need to source a suitable manifold & carb setup.

So...

What if I put my (already reconditioned) 1098 head & manifold on the 1275 block? I assume that I will still need the modded backplate & flywheel, but the majority of the cost would have been the exhaust system. I could then keep the normal morris carbs & exhaust.

I know that this will not get the full benefit of the 1275 performance wise, but are there any other ill effects?

Would it even work?

Cheers,

Chris.

[Peetee]

you can source a manifold from a Mini 1000. it uses a 1.5" carb and has a exhaust port the same size and orientation as a Minor. You can then use a standard Minor exhaust system.

[rayofleamington]

How about using the backplate form the 1098? You may have to re-drill a few holes to suit the block (use the 1275 backplate as a guide) but is far cheaper!
Then you would just need the modified flywheel to suit the different crank - this should not be very expensive!

You can use the head and carb from your existing minor, or the existing Marina head (better), and either the original carb + manifold or a Mini one.

The Marina also has the leaky scroll seal!

Your cheapest option would be to convert the Marina engine to fit a Minor and then sell it on ebay for £100+
then buy another 1098 engine for £50 ;-)

[bmcecosse]

You cannot put the 1098 head on the 1275 engine ! Well you can, but it would be madness. The Bull costs are excessive - shop around. As said - Mini manifold will be fine, and I believe I have heard of an adapter piece to use the 4 bolt 1098 flywheel on the 6 bolt 1275 crank ? Anyone ? Dunno about backplate differences - I wouldn't think there could be much in it - maybe just a bit more clearance around the rear oil seal ?

[les]

The backplate needs the starter motor hole slightly repositioning and dowel holes resizing

[Cam]

I believe I have heard of an adapter piece to use the 4 bolt 1098 flywheel on the 6 bolt 1275 crank ? Anyone ?

That does not sound too healthy and would push the flywheel out quite as bit if it was meaty enough for the job.

Here is a picture of the 'usual' modified flywheel:

http://potteries.mmoc.org.uk/Members_Ca ... 402_04.JPG

As you can see, two of the existing holes are used and an extra 4 drilled. The advantageof one of these flywheels is that you can just bolt it back onto a 4 fixing crank if needed later on...

[rayofleamington]

What if I put my (already reconditioned) 1098 head & manifold on the 1275 block? I assume that I will still need the modded backplate & flywheel, but the majority of the cost would have been the exhaust system. I could then keep the normal morris carbs & exhaust.

reading your question yet again - I'm not sure if you are already aware (probably) but you can keep the 1098 carb, manifold and exhaust with the 1275 engine, whichever head you choose.

[Peetee]

but you can keep the 1098 carb, manifold and exhaust with the 1275 engine

That's a good point to make Ray. I don't think anyone had made it clear that many parts are interchangeable as the engine is basically the same external size and layout. However getting it to run well could be a challenge!

[bmcecosse]

The flywheel mod is very interesting Cam - I was wondering if this could be done. I have a 1275 crank (still searching for a block !) - and have been looking at the flywheel to see if it could be modified - but someone else mentioned the 'adapter' idea - which I agree must push the flywheel even further away from the crank. I was thinking of drilling the flywheel - but was a bit concerned that would be considered 'gung-ho' !!!!

[Cam]

bmc, it would be 'gung-ho' if you used an electric drill and tried to drill it in a vice. It needs to be accurate, so unless you have the proper equipment to set the hole angles accurately and use a pillar drill and drill it to the exact size (don't want any slack) I would not bother.

[catsoup]

Thanks for all the replies.

I like the idea of keeping the 1098 manifold/carb and exhaust for now. Providing I can get it to run okay, I could always upgrade these bit by bit (in the warmer weather!)

Anyone know what problems I will encounter getting this to run smoothly?

I will get the old flywheel off and see if a local machine shop can drill the extra holes. (Thanks for the photo). While I am there, I will also ask about the backplate.

Cheers,

Chris.

[Cam]

Chris,

You might find that a carb needle change is all that is needed, but you could always try it first. It might be ok, but of course the engine will be down on power (for a 1275) but will still be better than the 1098.

[rayofleamington]

I like the idea of keeping the 1098 manifold/carb and exhaust for now. Providing I can get it to run okay, I could always upgrade these bit by bit (in the warmer weather!)

Anyone know what problems I will encounter getting this to run smoothly

some of it will be luck - I've run a 1275 midget using the 1098 carb/exhaust/manifold and it ran beautifully. I didn't have to change needles but my carb was running rich in the first place. I was probably loosing a lot at the top end due to the poor gas flow ancillaries and also due to not having the correct needle but it really had 'torque' to be proud of (80mph up a hill on A38 where the 1098 had managed 60)!
If the big ends hadn't died due to oil starvation (no oil filter blocked warning light sensor on the MG's ) I doubt I would ever have removed the engine.

[catsoup]

Good stuff! Thanks guys. I will keep it as standard as I can, and see if I get lucky.... 80mph - gosh....

Tho mine did used to read 60 90 60 90 60 90 60 90, and if you blink at the right times its quite impressive..... But that was fixed when I changed the speedo cable.

Thanks again,

Chris.