Thanks to both Ron and Derek for the helpful responses.
I've attached two photos of the carbs. Derek, I have pancake filters and not the box filter, despite my car being a 1969 Amazon.
As you can see I have the options for both types of filter. My carbs are the two bolt version but my blue filters are three bolt version (long, uninteresting story). I'm not fussed about originality. The slimmer (not blue) pancake filters are a cheaper option for me and, to my eyes, look nicer.
So, I could:
- Buy some new blue filters for my two bolt carbs.
- Continue using the smaller, fresher pancake filters but with no stub.
I think that either of these options would be fine, but I have an oil leak problem that I would like to solve before splashing out on new filters.
The third photo shows the problem. I have oil leaking from the filler cap. It is a reasonable amount and noticeable after only a few miles. I have tried the following without being able to eliminate the oil leak from the filler cap:
- Checked the manifold valve - the one between the carbs - definitely unblocked.
- Checked the red "ear" on the fuel pump side of the engine - definitely clear.
- Swapped the two pipes - the oil filter pipe to manifold and red ear to air filter and vice versa.
- Checked the oil level - I've just changed the oil. 3.4l of fresh oil and "spot on" on the dipstick (not too much oil in the system).
- Checked the rubber pipes - no blockages.
- Used only one of the two PCV rubber pipes - connect oil filler cap hose to manifold and vent the red "ear" hose to fresh air.
- Checked that the oil filler cap is unblocked - I can blow through it easily and have soaked it previously in paraffin to make sure it is clean (this is currently the second oil filler cap I've tried)
- Replaced the oil filler cap rubber gaskets. I'm using two malleable rubber rings (not crusty) and the cap is on nice and tight - it takes a good bit of force to undo it.
I'm sure I'm missing a really obvious solution to the oil leak. I think I need to resolve this before ordering some new filters (whatever they turn out to be). If anyone has any ideas, I'd love to hear them!
Ed