Catch cans

[mgbazza]

I'm considering fitting a catch can in the crankcase breathing system. Any suggestions as to the best method of connecting it ?

[Bill Young]

Barry, take a look at some of the race cars shown in the British Racecar section. Most of those have catch cans and many different types of connections from reinforced clear tubing to AN lines, your choice. One thing I can advise it to put some type of drain in the can to make it easier to flush out any accumulated oil. I know from experinece that it can be a pain to have to completely remove the can to drain it between races. In a well sealed system I don't see any reason you couldn't plumb the drain line back into the sump and recover the oil in that manner, just don't want to introduce any dirt or debris into the system.

[mgbazza]

The type of catch can I 'm contemplating has a drain hole, an air filter & 2 ports. It's where the ports are connected to is my main concern. Rocker cover to air cleaner or carby  ? Get rid of the rocker cover air filter ?  Keep the flame trap to carby connection ? Any advise or tips are very welcome.

[Bill Young]

If you're running a Rover engine then I'd advise three ports at least, One from each valve cover and one from the fuel pump block off plate. We've had oil drain back problems on the race car with only valve cover vents, hopefully the fuel pump vent will eliminate that problem. We're using -12 AN line from the fuel pump plate, -6 line from one valve cover and a 1.5" vent from the other valve cover.

[classic conversions]

The catch can should be from the upper section of the engine; valve cover and some cases the intake manifold.

If you are building a car to use on the track, check the rules of the sanction body, if running on a specific class or the track safety steward.

The idea of the catch can is to catch oil fumes that will convert to liquid and to help the engine breath at high rpm.
Keeps the oil away from the track to avoid havoc.

The one shown in the picture is a bit big but functional. Also notice that he has a breather hose from the front of the engine to the main line on the catch can, this allows breathing in the front of the engine such as timing chain, this area creates lots of pressure at high rpm.
 Some racing organizations do not allow a drain and if they do allow a drain in the can, it has to be safety wired.
Same with the lines, some rules are specific to steel braided hoses in case of a fire.
A plastic line would melt and add fuel to the fire :-)

[mgbazza]

It looks like this post has run it's course. Thank you for the tips & advice. Barrie E