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| Joined: | 03-14-2005 |
| Location: | Atlanta, Georgia USA |
| Posts: | 406 |
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Kate's original MkI engine died 4 years ago after injesting a loose carburetor nut that was supposed to be holding on the air box. It got pulled into either #2 or #3 and got pinched between the head and piston right next to the liner. There is a nice hex 'stamp' on her head and liner literally cracked in two. The worst part is she had loaned the car to another club member for an autocross event when it happened!
As far as catch-can strategy goes, the important thing is to have something - anything to catch the heavier oils and keep them from gunking up the carbs. The 907 is not a "fix it and forget it" kind of engine, and no matter what one does, the important thing is to keep constant vigil on little things like this.
Where people get into trouble is when they overfill the sump. Of course the intent is to minimize slosh and oil starvation, but this tends to cause other problems. Oil starts to pool in the head, the crank foams up the excess oil, and when the vapors do get a chance to excape, they take as much oil as they can with them!
My converted Windshield washer reservoir does not have a drain and it probably gets about 1/4" of sludge dumped out of it every 3-6 months. Of course that engine is a Nikasil 910 block with brand new pistons and rings. An older engine with older rings will naturally 'puke' more oil and will need more constant attention.
Even Kate's new MkII rebuild with the MkI catch can does collect a little oil in the factory air-box. Is the MkI catch can too small or can we conclude that pretty much every 907 variant was a bit prototypical and needs to be 'baby-sat' more than most engines?
Judson