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I have a 1275 that has the oil separator that just pokes up... to nothing (the front of the engine). Seems like there are a lot of permutations on where it should vent. Some seem to just leave it alone (like mine is), with the possibility of some stray burb of oil (that can be messy with the fan right there). I've seen some run a line to a T that inserts the ventilation to the line from the rocker cover vent to the back of a carb (though this spooks me if there is every a serious blast of oil toward the forward carb). Others have the metal PCV unit on the top (where it's probably supposed to go). It's a new engine.

I've read the various threads on this (such as https://www.britishcarforum.com/bcforum/ubbthreads.php/topics/753083/3), but, honestly, I'm not sure what the definitive solution might be. Can I leave mine as-is? Can I run it up to a simple breather? Can I combine it with the rocker breather? Should I install the PCV unit? Your thoughts would be appreciated. Thanks.
- Mark
 
Hi Mark,
It is my understanding that it is important to run the crankcase of a 1275 motor at a slight vacuum. This, I am told, reduces the rate of oil draining out of the engine, from the rear of the crankshaft, front seal, valve cover, etc. So, when I built my 1275, I used the Smith PVC valve, with the connection directly into the intake manifold and the other end to the oil seperator. It works for me, as the oil has stayed intside the engine, rather than dripping out.
Good luck,
Scott in CA.
 

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Thanks Scott. Yes, read about oil leaks that have been cured by establishing a little vacuum. Mine isn't leaking at all (yet), but I suppose it certainly wouldn't hurt to drop the pressure a tad bit. I have a threaded plug in the intake manifold, so it makes sense for me to acquire the PCV unit and hook it all up.
 
You know, in contemplating this further, it seems to me that early A-series engine didn't have the separator, and they did OK, didn't they? I'm pretty sure I started seeing these things about the time that emmission controls started to appear (in 1968 or 1969). Back then we'd pull all that stuff off... and, at the time, I think we used to believe that it was partly for the prevention of some kind of pollution. Were there any PCV devices pre-1968 on an A-series engine? Or is this a 1275 thing?

I think I realize the value of some vacuum, but wonder if it really makes a difference.
 
My 1275 dripped out the rear main every 2 seconds while idling immediately after its rebuild. I'm suspecting because the rings hadn't seated fully yet there was excess pressure from blowby entering the crank case that was pushing oil past the scroll seal on the rear main.

I installed the Smith's PCV valve pictured above and it doesn't leak at all any more while running, and only leaks a drop after being shutoff.
 
My 1275 is also new, though no leaks... but I have had a burp out the separator (under load), which I attribute to rings still seating. Makes sense, and certainly harmless, to install the PCV. Thanks!
 
The 948s and I think the 1100s had a draft tube out of the front tappet cover. In addition a hose went from the valve cover to the front air cleaner. The PCV valves were the first of the air polution equipment added to our cars, and I think you are correct, that was 1968. US cars, I think, were a couple of years earlier. The PCV and the closed fuel system modifications didn't cost anything for performance or mileage. Later air pumps, lower compression, modified distributors, etc, really robbed power until fuel injection and converters came to be.
Scott in Ca
PS, after my rebuild, my car smoked like a smoke stack, for about 200 miles until the rings set.
 
Most of the US cars were 66 or 67, but California started earlier than that. I know 1965 Mustangs had factory PCV in California.
 
I remember having an Austin America that had all the emmission stuff on it and it REALLY compromised performance. It was a 1969 one. I think the top speed was about 75, but when all that (notably the air pump and related stuff) was stripped off, the top speed went to about 88. At that time you could do it yourself (if you knew how) or there were actually shops in Vancouver, BC that had a thriving business going for all that. Of course, this was before fancy emmission-testing was being done for registration (now, thankfully, exempt).
 
Boink said:
I remember having an Austin America that had all the emmission stuff on it and it REALLY compromised performance. It was a 1969 one. I think the top speed was about 75, but when all that (notably the air pump and related stuff) was stripped off, the top speed went to about 88. At that time you could do it yourself (if you knew how) or there were actually shops in Vancouver, BC that had a thriving business going for all that. Of course, this was before fancy emmission-testing was being done for registration (now, thankfully, exempt).
Click to expand...

don't want to hijack this thread but that is the first time I have ever seen the words "Austin America" and "performance" in the same sentence.
grin.gif
 
Hehehe... well, it was a spare car and a bit of a kick. Except for the hydrospastic suspension that periodically lost fluid, it drove like any other MG 1300. The prior owner had put, get this, ARCO graphite in it for lubrication... and what with routine leaks, what a mess. Black everywhere. And once you've gone to that stuff, you're sort of stuck with it. [No, not that old joke.] :laugh: Can't remember who I dumped that on. :yesnod:

And, in defense of me, I was about 16. At least it was a manual tranny! Remember those things could be ordered with an automatic.
 
Whatever you do, don't connect it to the valve cover. My car's po connected it to the valve cover. It leaked oil like crazy. I had a local MG/AH shop try to address the leak. They installed new oil pan gaskets. No help. They said I needed a front engine cover gasket. An engine pull and almost $600 later for a gasket I did not need and no improvement. The thing that kills me it that I pointed to that exact hose the first time I took it there and said "I don't know if this stuff is hooked up right because the emissions were removed and the carb changed. Can you make sure these hoses are reconnected correctly?" The answer was a quick "yes, they are fine, we need to change your gaskets."

When you want it done right do it yourself. After learning what every part of the emissions system did, I realized how important it was to disconnect that hose. I always planned on getting a breather filter for it, but the old hose just curled up works fine to vent and contain any oil splash.
 
As for the Smiths separator, I feel any PCV plumbing will do the job if you so choose. The main issue is to create the vacuum to relieve the internal engine pressures. That being said, there are issues which any PCV system won't solve i.e.. new rings not settling, worn valve guides on older engines...etc etc
 
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