Morris Minor Owners Club

I've recently fitted a 1275 midget engine which is running with a std minor exhaust system, and seems quite ok.

Reading posts on here and other forums, it seems many fit larger bore exhaust systems, can someone explain if I need, and why, to change my std system.

Many thanks

Graham

If it's working for you I'd leave it alone.
Any strangling effect it might have will only be noticeable a higher revs anyway.

MarkyB wrote:If it's working for you I'd leave it alone.
Any strangling effect it might have will only be noticeable a higher revs anyway.

Thanks for the reply.

There was a thread in July regarding exhausts on 1275 engines, but I'm still no clearer what are the advantages of a larger bore system.

I said previously that the car runs ok, but that is ok compared with...........................what, would a larger bore allow it run more ok, ok+

Advice would be appreciated, thanks

More power!

A from my own experience, quieter than standard at low rpm.

chrisryder wrote:More power!

A from my own experience, quieter than standard at low rpm.

Thanks...................I'm sure the engine is lacking in a little power, so that would, perhaps, explain it.

You appear to have twin carbs fitted too though, does this mean you have a standard manifold cut in half? Or maybe a cast marina/midget one?

Alex'n'Ane wrote:You appear to have twin carbs fitted too though, does this mean you have a standard manifold cut in half? Or maybe a cast marina/midget one?

Hi

The engine is from a midget, the manifold as well, with the existing exhaust persuaded to fit, hence my interest in replacing the exhaust system. Like I said car runs well, but I have nothing to compare it with.

Manifold similar to this

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I thought the Midget manifold was unique to the car and brought the exhaust too close to the block to fit a Minor exhaust down-pipe to.
However, if it's gas tight and runs well, then leave it.

The tiny twin carbs are not the best - not much better than the single small carb (each port still sees only a single 1 1/4" carb - but at least there is no power robbing hot spot !!) - so the engine won't be developing all that much power - maybe 55 bhp. The standard Minor exhaust was designed for the old 948 engine (maybe even for the 803 ??) with all of 37 bhp - so on a 55 bhp engine there will be considerable restriction to flow - causing back pressure and loss of power. A decent exhaust would be worth an extra 5 bhp to you.

As a footnote.......I've changed the exhaust system and I'm pleased with the difference it's made, not sure about money well spent, but there's no pockets in a shroud, so hey ho.
Pictures don't show much, but may be of assistance to someone
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[frame][/frame]

Interested to hear how the difference manifests itself, more torque, more power at higher revs?

MarkyB wrote:Interested to hear how the difference manifests itself, more torque, more power at higher revs?

I found with the engine change initially, that she wasn't quite as lively as I expected, better that the 1098 but I thought it would be better in acceleration. Cruising was easier, I put that down to the 5 speed gearbox.
However all the improvements I'd hoped for are now there. She pulls away easier, and has a tad more power, which was what I wanted.
I've only driven her a few miles, but over time I'll see if she fulfills my requirements