I have a 3.8 fitted to my Mark 2 and the twin SU carbs run a boxy type of air filter system.
I have purchased some ram tubes to fit to the SU carbs but am at a loss as to how to block off the identified hoses----or where does that connect to once the ram tubes are fitted.
Any (wise) suggestions?
Thanks in advance~
That’s the crankcase ventilation - definitely don’t block it off. Once the air cleaner system is gone you can run a draft tube straight down to the bottom of the car like the older cars had. Basically just a tube with a 45 degree angle cut. The long side of the angle goes toward the front.
Thank you, sir-- just the same sized pipe as original?
Yes same size will be ok.
Thank you guys—your help is much appreciated
Rather than run an old style draft tube and vent the hydrocarbons to the atmosphere better to plumb it in some where in the intake system where there is a slight vacuum such as the air filter. These positive crankcase vent systems help keep the engine oil clean as well and having a small vacuum on the crankcase might help to reduce oil leakage at the problematic rear main seal
I would say it is better to try and plumb it into the inlet side , maybe drill and tap a thread in a inlet , and add a tube !
I l like you small carb air filters. Where can I get ones like yours?
Ian
They really are pancake filters!
This is what many BMC cars used starting about 1964, a Smiths positive crankcase ventilation valve (the round thing with the hoses attached) that meters the vacuum from intake to the line leading to the oil separator which drew from the crankcase. Believe some Land Rovers used this as well but never seen one on a Jaguar. This photo from my Morris Minor which I retrofitted this system to since it was made prior to these being standard factory fitment and relied on a draft tube only in 1960.
I wonder if those pancake filters affect performance; they look quite restrictive and require air to perform a 90 degree turn in a tight enclosure. Not a nice long straight ram tube effect. Anyone know?
I had them laying about , they was off my old GT6 , just had to make the mounting holes a little diffrent , and of course make the inlet hole bigger .
I replaced the foam , you can by that on e-bay in sheet form .
Not restricted at all , as the air can get in all the way around !
Thank you all
My one problem appears to be the air conditioning unit sitting on top of one carburetor.
Thanks for the information I will look into buying them. I am also looking for a repair shop on Long Island NY to do a valve adjustment.
Thanks
They say that you have to change the needles when going to a different air filter.
Why would external filter cause a change in the carburetor needles?
FIlters will richen your mixture. I recently tuned my Mk10 with the air plenum removed because it’s a pita to mount, wound up with richer needles because of a lean miss on wot acceleration, only to return to stock needles after re-tuning with the air plenum/filter system on. The amount of richening will vary depending on the resistance of the unit. The pancakes don’t have much. I had a Volvo PV544 with B16 engine that simply would not run without the air cleaner. A guy rebuilt the engine for me back in the days before I did that sort of thing myself, and called me, frustrated out of his mind that he could not get it to run. I told him “put the air cleaner on and try again”. It fired right up.
So always do your final tune with whatever filtering system you plan to use.
What he said, no or less restrictive air filters make it leaner 
The well respected A series engine guru, David Vizard, did loads of air filter tests a few years back and concluded that the thin pancake filters do not flow any where near as much air as a factiry filter. At the time K &N filters with a small ram pipe was best.
The very small filter area, the 90 degree edge and the very small gap between the carb opening and the plate made them very restrictive. And that was on 850cc engines with 1 1/4 inch carbs.
