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Discussion Starter #1
anyone know if the crank breather change-through the main bearing-works better than the rotary disc in the inlet cam?

thinking of doing this while I've got the cases apart and maybe venting through the timing hole behind the inlet cam. Would I need a non return valve on this, or should it suck and blow.
also, are there any other thing I need to do to make it work (besides leaving out the oil seal on main bearing and drilling overflow holes through to chaincase-I also have some cams off a 71 that I was going to use)
 

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Discussion Starter #2
I just heard about breathing through the chain inspection cover. If I went this way, and changed to later cams, would I need to block up the old disc breather hole?
I'm considering this mod because the 68 motor I'm putting together with the breather disc, the inlet cam just doesn't feel smooth-it springs up, but is a bit sticky when it turns. I'm about to bolt the cases together for the second time and if it's still sticky I'm thinking bugger it I'll just use some nice 71 cams I've got and breathe out the main bearing
 

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It could just be the tabs on the breather disc aren't central,or the slot in the cam isn't dead centre.It might fit better if you rotate the disc 180 degrees on the cam.You might need to grind the tabs,so it fits better.

If you use the later cam,leave the disc and spring out and plug the breather pipe.Just glue a bolt into the pipe with silicone sealant or something similar.I think I used a 5/16" UNF allen screw;might have had to run a tap into the tube to get it started.The tidiest breather will be out the filler cap on top of the primary.A 90 degree hose fitting looks OK.Drill the 3 holes in the primary and leave the crank seal out.

The other alternative is to breathe at the front of the engine,between the crankcase and front engine mount.You drill holes from the crankcase into that cavity,and run the breather out the top, between the barrel and engine mount.The holes from the crankcase are drilled at 45 degree angle,to catch less oil.Oil drain holes are drilled at the bottom of the cavity.It's been described on "The Jockey Journal".It could be very effective with a one-way valve.
 

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Discussion Starter #4
turned the disc 180 degrees and there definitely seems to be a position that fits better, also bent the tangs inward just a pinch and reamed out the timing side bush a whisker. Bolted her up and **** hot, it's all nice and free. Thanks heaps.

By the way--I notice that the "springback" on the cam is gone after I fit the intermediate pinion-does the spring action then happen at the other end of the shaft, where the disc is? I'm guessing it does, but doesn't hurt to ask.

Today's job--gearbox
 

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Mossy, Im very interested in this as Im working on a 66 T120 motor , it has a belt primary against a chain so chain case has been opened up to cool belt. as there is no vent now Im worried crank pressure could blow a seal as it puffs out of the oil tank.
are you running chain primary still ?
 

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The '66 engine should have the timed breather on the the intake cam,and a breather tube in front of the gearbox sprocket.A crank seal fits on the primary sprocket,to separate the crankcase from the primary.The lip of the seal faces outward toward the primary,and your belt pulley should fit into this seal.

I doubt that you need air-cooling on the belt.You're more likely to find that road dust etc is wearing out the belt and pulleys faster than if they were sealed and protected from the elements.
 
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