Series 3 Oil Hiccup - Pressure build up ?

Hi ,
Finished adjusting the door hinges this weekend , and went out for a long hard drive , including some steep / steep hills - got home to discover that the engine had blown oil ( maybe 1/2 pint , looks worse than it actually is ) out through the oil breather stack
.


Cleaned up now , but believe it must have been some sort of pressure relief issue . Am looking for a bit of guidance , A while back , when I got the vehicle I posted about the fact it had no oil bath , and concern over the pipework - I think this has something to do with it , it has just a direct connection from the breather on the top of the rocker cover to the base of the carb , see bottom right , with no T into the Oil bath hose like the standard set up . My initial thoughts are to T into the direct connection and add a motorbike style breather filter , hopefully this will allow more relief , - Thoughts ?
Cheers Steve

I've not seen one like that with the breather on the filler and the rocker cover top. I bet that's not even 1/10th of a pint, a little oil makes a lot of mess.

It looks to me like you've had a couple of backfires and its blown oil out due to the positive pressure in the rocker box. You must have a better rocker gasket than most!

Somebody (when fitting paper filter) has removed the T-piece on the pipe from the carb to the breather that goes also to the air intake. That is there to a) on overrun stop the carb sucking out and burning all the engine oil. b) on backfire doing what has happened to you- check oil level, is it over full. You could refit the T piece and add a small paper air filter to the T.

Personally I'd ditch the filter on top of the carb. I've done a fair bit of testing with these and the oil bath filter doesn't (measurably 0-50 times or mpg) restrict air flow even on a tuned engine. Though you may like the extra noise! (I still have a cone filter but that's because I have a DMTL carb fitted and the pipework doesn't fit easily and I managed to tear my extra long pipe).

Other things to check
- oil level - is it over fullt?
- check timing (may be too retarded)
- check vacuum advance pipe (again will be too retarded on overrun) Yours looks to be routed round back of engine, it may have burnt through on the exhaust

The other options is that you can get a kind of one-way valve to go between the breather and the carb which should cure and back fires getting into the engine - I can't remember what they are called though.

Thanks Dominic,
I'm re introducing the "T" piece this weekend , and will also check the timing & vacuum pipe , though I doubt that , as it's an original copper one , bit like an oil pressure line . I'll check timing as well.
The idea of reintroducing the oil bath is always there , though for me that'll also mean getting a cradle as mine has been hacked off , I've seen them on e- bay , running at about £100 +, at the moment I'm organising new tyres so , that's not the kind of additional expense I'm keen to make . However I might stick a "Wanted" ad in to see if I can organise something ....
Cheers
Steve

with the breathers removed and the engine running what if any blow back does it have?

I'll keep my eye out for a cradle, I saw a whole pile of them going to scrap at one place I visited but of course they are never needed when you have lots and expensive when you need one!

I'd double check the advance pipe, copper pipes can crack, the turbo governor on my bus used to go after a few thousand miles and was notorious, a couple of compression fits and a bit of random air line and it never went again! Also check the diaphragm and whether it actually works by sucking and checking timing with a timing light. Do you notice it popping a lot on overrun - it would have to be bad to make a mess like that!

You may have just had a couple of big misfires when it was cold - I know mine backfires violently through the carb when it is cold and not given quite enough choke - I had the missing eyebrows to prove it when I was setting it up after doing the head - I had no ari filter at all and I snapped the throttle open and got blasted!

D