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MG Midget and Sprite Technical - How to identify 1275 camshaft?

With my midget came a number of brand new engine spares, which I assume are from a 1275 A-series engine. Among them is an unused camshaft still with its protective grease coating. How can I tell what it is?

Likewise there two sets of valve springs - any clues as to what they are?
Mike Howlett

Camshafts either have a number stamped on them or there are various other markings, such as rings around the shaft.

Vizard has lots of info on IDing camshafts.

If it's from a pre A+ 1275, it will have the 'spider' oil pump drive, unless it's from a Cooper S.

Anything smaller than 1275 will have a pin-drive, as does Cooper S.

A+ camshafts are all slot-drive.

Once you've established which oil pump drive you have, it is easier to ID it.
Dave O'Neill2

Have you any pictures?
Growler

pictures.

we need pictures.
d cusworth

I actually have Vizard's book but didn't think to look there - doh! Anyway, here is a photo of the camshaft. It has a spider drive and 1/2" wide lobes. There are no rings, and no numbers stamped on it either.



Mike Howlett

stumped!
d cusworth

I have an old original BMC 1275 cam shaft that has no marks either.
Lawrence Slater

Lawrence, me too....

Mike, spider drive equals early but after that it's out with the protractors and vernier to do some measuring. If you are up this way drop by and we can compare it to a couple I have knocking around the garage from a transverse 1275, a Kent 266 (I think) and a SPi scatter.

If anyone in the UK wants an SPi scatter get in touch...

As far as the springs are concerned, you could try and set up a rig to measure the rate (sounds like fun :0). After that its just a case of counting he coils and measuring the free length and diameter. Closed length eg distance between the head and underside of the cap is needed along with the cam lift to determine if there will be any spring binding in use, but I think I'm getting ahead a bit here ;0)

best of...

MGmike
M McAndrew

Camshaft - measure the lift on an inlet lobe and an exhaust lobe. That will considerably narrow the field of options. A photo taken from one end showing clearly the shape of an exhaust and an inlet lobe would help too. (Best viewed from the back of the camshaft looking at no4 ex and no3 in). Between these two bits of information is should be possible to at least identify the generic type (std-ish, mild fast road, etc).

Valve Springs - I have a rate calculator spreadsheet if you can provide the wire diameter, coil ID, number of turns and free length. For simplicity count the total turns including the tail where it tapers to nothing at ech end.
Paul Walbran

Thanks everyone. I'm away this weekend at MGB-50, but will try to supply what Paul from NZ asks next week.
Mike Howlett

I might see you there...although I'll be without the B, as it is still in pieces!


Dave O'Neill2

Dave,
Your B looks like its coming along very nicely.
Looks like a perfect opportunity to put the steering on the correct, I mean right side. ;o})
P Burke

Phil

It's funny you should say that. It was originally LH drive and was converted to RH drive in the '70s.

I've just reinstated part of the bulkhead where the LH drive column would be, just in case I need to convert it back.
Dave O'Neill2

This thread was discussed between 16/09/2012 and 21/09/2012

MG Midget and Sprite Technical index

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