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MG Midget and Sprite Technical - A+ crankshaft rear oil seal

I see on my newly acquired A+ block that the crankshaft rear oil seal is a concentric ring labyrinth type which I assume does not use any other seal - any oil getting past would appear to drain back though the lower half of the bearing journal into the sump.

Am I correct and is there anything I need to do to this seal to make it suitable for sprint/hillclimb use?

Thanks

John

John Turner (Midget & MGB)

It's just the standard A-series rear scroll seal.

It's not advisable to remove the upper half which is held on ot the block with three screws, as it can be difficult to set the correct clearance.

If the main bearings haven't been run, it should seal OK.

Some people claim that they don't work, but I've not had a problem on the majority of my engines. You just need good crankcase ventilation.
Dave O'Neill 2

specifically for hillclimbs, if you stop for any reason, get the car somewhere level; if you leave it parked on a steep bit it has a habit of running out in copious quantities !
David Smith

David

Thanks - I haven't ever stripped the bottom half of an A series so didn't know what to expect. Reading about problems with the rear oil seal I thought this may be an improved version developed for the A+.

The sealing face on the crank looks good as do the bearings so hopefuylly it won't give me problems.

Will try not to stop on a hill!

Thanks again

John

John Turner (Midget & MGB)

Was it you that centre strapped the block (photo in other thread) or did the block come like that?
Daniel Thirteen-Twelve

Daniel

The block was centre strapped when I got it. Reading Vizard I understand that the A+ caps do not have a central groove and are therefore stronger so perhaps the strap is unnecessary?

John
John Turner (Midget & MGB)

Interesting point John. I'd guess that the stronger A+ cap simply moves the safe rpm further up the range before there is a requirement for centre strapping. I'll bet the classic Mini gear still go all the way to a 4 bolt centre main for their racing A+ engines.

Still, it's a nice mod to have and gives you some assurance when you see the tacho passing rapidly through 7K on the way to 7.5K+
Daniel Thirteen-Twelve

Obviously I will keep the strap as 'insurance'.

Thanks to all

Again, the BBS is a fantastic resource for midget Men (!?)

John
John Turner (Midget & MGB)

John

When you order bearings and rod bolts make sure you specify 1275 Marina/Ital rather than Midget as the big end size is different and the rod bolts are different - ARP do rod bolts for the A+ and are recommended because the standard ones were made to a budget by Rover...

James
James Bilsland

Oh and you will find that a 1275 Midget Flywheel will not fit either (you may have a modified item already on your engine) - there is no taper or dowels on a Marina crank

For future reference what you can do however is offset grind the big end journals to Midget/Cooper S sizes, use Midget Rods and increase the cc of the engine to 1426cc... :)
James Bilsland

Actually I seem to recall that Marina Cranks have 1 dowel?

JB
James Bilsland

James

Thanks, a few interesting points raised.

I have just measured the big end journals (using a vernier caliper) and they are 1.850" and the rod bearings reflect his. The crank has a single dowel. So it looks as if I have a Marina/Ital crank and I will need to order bearings to suit - good call.

I shall be sticking with the 1380cc as I compete in the MSA under 1400cc road legal class

I haven't got my 1275 Midget engine out yet so don't know if the flywheel will fit the crank. I am planning to have the flywheel lightened so can get the locating diameter machined if necessary then.

John

John Turner (Midget & MGB)

Yes, Marina has one dowel.

I thought b/e diameter was 1.75" ?
Dave O'Neill 2

David,

Ooops - can't read a vernier properly - you are correct 1.750".

Thanks again

John
John Turner (Midget & MGB)

Might be better machining the crank with a taper and additional dowel so you can re-use the flywheel with a standard Midget crank I would have thought - depends how many Midget flywheels you have I suppose...

JB

James Bilsland

This thread was discussed between 20/12/2010 and 22/12/2010

MG Midget and Sprite Technical index

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