Crank Case Inspection
- Thread starter Pushrod Twin
- Start date
PT the large idler spindle and alloy boss..throw them in the bin and get a two piece steel item. Your guesstimate at the shaft clearances are correct, and same for cam bushes to cam spindles. If your cam pinions are original well used ones throw them away and buy new ones...this will give you the hunting sound you described, due to the loading/ unloading effect of the valve train as the wheels ware over time. Set up each individual cam follower exactly over the cam lobes, and use shims as required to achieve this....NOT......just as per what the book says, sometimes you even need to grind some off the inner face of the follower pivot boss to align correctly with each lobe. Use new cams and followers if the old ones are worn, not many originals of either aren't, and make sure the ball ends of each pushrod spins and pivots freely in each follower socket, as they can hang up, not seated correctly down the hole causing tappet clearance issues....check same at upper tappet adjusters, as if these are tight, it can fracture the socket sides of the adjusters.......I think many of the finer dimensions you need, you are best contacting Clevtrev, there are probably less than 1% of anyone on this forum with the kind of details you are asking...Remember it is an air cooled motorcycle engine with some level of complexity over other engines of it's time.....You are not rebuilding a Merlin..I to have spent years in the aviation game, it is not an even playing field to compare a motorcycle engine to something that will plummet from the sky if something goes wrong. I understand what you are trying to achieve, I am just not sure it is easy to convey all that info on a forum. I look forward to your continued progress, cheers for now...........Greg.
P T, the reason for question about et 50 is I couldn't see the holes where the box spanner goes so you can tighten its adjustable mounting. Roy.
Well spotted Roy, Cheers Bill.
Only the Series D items were one piece. No suppliers seem to want to make them this way. Avoid the two piece items with the aluminum base. The two piece units available new seem to be fine, but I have only used Maughan's.
David
Quite right Roy. There are none! The 4 small holes which do exist are neither in line with the studs nor big enough for a socket to pass through. Who ever fitted this probably spent some tedious time feeling the back lash, dismantling the steady plate, making adjustments, reassembling etc etc! Or not. But it has lovely teeth
. Too good to scrap, I figured that I would drill three large holes to correspond with the PCD of the stud holes, then I waved a file at it & thought; ooooh! that might not be a 5 minute job in the drill press! Might have to apply some carbide technology in the mill to the hole making process.
P T , I'd reccomend a trip to the laser cutting guys. They saved me a fortune in time and agravation on my project. While you are at it, a few extra lightening holes will reduce it's inertia. the same goes for the camwheels as well. Regards, Roy.
Good thinking Batman! I can have that done over in the Fabrication side of the general engineering works, where I am these days, for nix, I am sure the lads who run the cutter would do that for me. But I wont meddle with my nice new cams wheels & MK III's from Gary Robinson.