ET: Engine (Twin) Modifying the Valve Lifter Mechanism on 1,000 cc Engines
- Thread starter timetraveller
- Start date
No Craig, it seems I have not made it clear enough on the drawing in posting #1 above, The piece in the right hand side of the drawing is a blanking piece which is pushed and then peened into the opened out end to the part in the left hand drawing. The idea is that a similar part to the original is made but with an opened out inner end. Pushed into this is first a flat piece of oil resistant rubber which has a central hole which is a clearance on the spoke. This is then held in place by the steel blanking disc which is the last part to go in. This is a tight push fit into the opened out end of the original and then the end peened over to prevent it ever coming loose. The motion block which takes the nipple of the cable sits on the oil proof piece of rubber which then acts as a seal. The hole in the oil proof rubber and the blanking plug are just large enough to allow an easy passage of the spoke and the motion block then sits firmly on the oil proof rubber. The whole idea is to prevent oil ever getting into the ET169 and not to stop it getting through. If you work out the pressure being exerted by the motion block on the rubber seal and the area of the total clearance for the holes through which the spoke passes then you will see why it works. I would never guarantee that no oil could pass. All I can say is that in practice any oil is not detectable although a concourse expert with some talcum powder might be able to find some. The idea is simple enough that anyone with the time and a lathe could easily make this mod themselves.
I cannot see why having any rubber seal on the oil side of the 1/4" plug may be more desirable than have it on the air side where you could easily replace it . When the seal leaks it does not matter on which end it lives. I´d prefer Craig´s very simple type, just have the through hole in the plug countersunk with an 90 degree chamfer so the o-ring gets some idea to press onto the motion block´s diameter as well and does not expand in time. Some swivelling of the spoke part from hanging on the lifter lever inside does not matter when the o-ring is located in the chamfer. I would not want to "improve" things by having to undo the timing cover for changing the seal, be it unlikely or not.
Vic
Vic
Yes, I was just out in the shed trying to find one to measure but the only one I can find is in an engine so not easy to get accurate measurments. If the shaft of the ET165AS is 8 mm and the larger part at the end which take the cable nipple is 12 mm then I cannot see an 'o' ring being happy to stretch that far. If anyone has more accurate measurements we might make progress or maybe I have not understood what Vic is suggesting.
I knew that I had a picture of a different approach. I don’t know who did it but it looks like a simple way to avoid the knitting needles or having to hinge a rod. Would it be easier to make oil tight?
Ian,
mine is exactly as your photo. A chunky "O" ring on the outside. [which indeed I have changed from outside; tricky but do-able] A replacement ET169 Ferrule, the ID of which is a close fit [to help avoid oil loss] to the shaft of the replacement ET165AS, which as your photo shows is a chunky Bowden cable inner. This "looses" the arc movement of the standard ET165AS.
I made my own, but years back I think the idea was Mac Read's, who made some, and possibly Clevtrev.
Has worked fine for the last 22-odd years.
Regards,
delboy.
mine is exactly as your photo. A chunky "O" ring on the outside. [which indeed I have changed from outside; tricky but do-able] A replacement ET169 Ferrule, the ID of which is a close fit [to help avoid oil loss] to the shaft of the replacement ET165AS, which as your photo shows is a chunky Bowden cable inner. This "looses" the arc movement of the standard ET165AS.
I made my own, but years back I think the idea was Mac Read's, who made some, and possibly Clevtrev.
Has worked fine for the last 22-odd years.
Regards,
delboy.
Studying the photos I´d think the best combination is Craig´s o-ring plus the b´knighted Bowden inner wire to replace the length of spoke with its bending mode. The recess in the 1/4" plug for the o-ring should get a chamfer the o-ring sits onto, not a parallel shoulder, as a chamfer handles misalignment or bending better for reliable seal. Unlikely to have to replace the o-ring ever. Streching it is no drama when no sharp edges there to cut it in a stretch.
Vic
Vic
Sorry, I made a mistake, the hinge I made in the valve mechanism is of course not in the ET166 but in the ET165AS. The next time I have to open my engine I will take a picture, (but hopefully that will take a long time).