Crankcase pressure Leaking oil dipstick

[Britishbest]

Thank you Alan. Will feed back results when rebuilt.

[Britishbest]

Well after 2 attempts and lots of head scratching I realised the needle bases weren't level with the bottom of the piston base so too much fuel was getting past the needle hence why it was running rich. Such a tiny thing makes a huge difference.

 

Another critical thing is the tightness of the 4 screws that hold down the carbs main head, do one slightly too much or little and the piston wont fall freely so lots of adjustments made.

 

I ordered some lean 2H needles and once fitted flush the car is running nicely, a little bit of popping but for now I'm very pleased.

Edited June 5, 2016 by Britishbest

[oldtuckunder]

Thanks for letting us know, glad you got somewhere, Also thanks for posting the original issue, as it helped me solve a problems today. I was trying to set up a 175CD on the bench for some piston lift data logging tests, and whilst it had been stripped and cleaned and everything appeared spot on I couldn't get the piston falling cleanly without spring or damper no matter what I tried. Then I remembered telling you about ensuring the cap was in the correct orientation and that they quite often got messed with as people didn't realise the significance of the alignment marks, a bit of experimention showed that this carb had spent most of its life with the cap set 180deg out and had settled in that position. Now working like a treat!

 

So I guess my recomendation now ought to be if it isn't dropping smoothly and everything else checks out, also check that moving the cap through the four positions available doesn't resolve the problem (even though I hate to see them in the wrong place).

 

Alan