Just referring to a couple of engine parts:

1. My engine has what appears to be a split pin hanging through the bottom of the clutch housing area. Have seen it on other engines and its the same.
It is supposed to be split, cause mine just hangs there and is free to move.

2. My bigger engine has what looks like a small muffler coming off the back end.
It points straight up.

What are they and what do they do?
Thanks.

i have the split pin on my 1100 and that little thing on my 998 that looks liek an exhaust, i dunno what they are either

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Potato

I'm going to take a guess casue think this is right. THe hole is a drain hole and the split pin just hangs there to stop the hole clogging up with shite.

But there is nothing stopping the pin going back into the clutch housing.
Everytime I see one it is never bent.

i think that thing on the back of the engne that looks like a muffler is something to do with the breather system? although on mine neither end is connected...

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78 Leyland Mini - Prince

split pin is to check and disiapte oil in the bottom of the bell housing.
THe muffler on the back is a breather on the back of the motor.or on the timing cover.

Is the breather needed? One of my engines doesn't have it.
The hole is just blocked up.
Is there any benefit for one way or other?

All engines need a breather of some sort. Otherwise, they blow seals due to crankcase pressure. Big motors need more/better breathers.

If yours is `blocked up' it's probably got that weird 1098 `squished bit of pipe' and a breather (of sorts) from the rocker cover to the air filter.

Later Minis and S's had a PCV (Positive Crankcase Ventilation) system which fed the crankcase vapours either into the manifold via a PCV valve, or into the side of the SU carb.
Better setup. The slight vacuum on the crankcase helps stop oil leaking through seals too.

You can also run breathers just with filters on top (which usually clog up with oil) or pipe them into a catch tank. A Fosters beer can looks cool...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

yep, keep the breather, its a good thing. Especially on a 1275. Without one, the crankcase pressure can blow oil straight past your gaskets and seals, creating oil leaks that needn't be there. You will notice that a 1275 oil cap is different, too. They have a breather inbuilt. More the merrier.

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Cheap, Fast, Reliable. Choose two.

My 1430 has 5 breathers on it in total and works like a dream.
I had a mate who built a 1275 with no breathers on it and it would run fine for about 30km and then blow heaps of oil out of the oil filler cap and the main clutch seal, took him months before realising that the breather on the clutch cover really does need to be there.
Had a guy in south island who said he has bad oil leaks from his diff seals and wanted me to sell him some seals, cut a long story short, he had 1 breather on a 1330 motor and he put another 2 on and he recons oil leaks have stopped and runs better than ever before.

moral of the story: if you have wind do you recon you could run better without relaesing it or not?

can we get some drawings or pictures of the setups that you all have so I can see if mine is et up correctly.

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A Bloody Mini

1970 Mini K, 1380cc, 1.75 HIF SU, 30 70 Cam, 2" Zorts
1969 Mini K, Stock Standard and Orginal. (Slow as Hell)