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| SABB valve job |
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| Divided he ad:
:poke: :whip: :poke: :wave: :worthless: Ralph. :) |
| AdeV:
* eh? What? Who? Sorry, been busy away from the machines.... and I'm too knackered to do it tonight (I'd be dangerous on a machine tool tonight). Tomorrow.... maybe :thumbup: |
| Divided he ad:
:lol: I know you've only just got the mic' for the bores. No hurry, just thought I'd wake you up :) I can talk, the amount of half done things in my workshop! I just want to see the result with the seats :thumbup: Keep us posted. Ralph. |
| AdeV:
No worries Ralph, I'll be getting around to it soon... First job is to further bore out my practice ali piece, to make sure I can hit the dimension with the boring head. Assuming that goes well, I can crack on boring the actual head out, etc. More news Real Soon Now :) |
| AdeV:
Well, that took longer than anticipated.... :poke: Right, first up, in true Oscars style, I must thank a couple of people: - John Bogstandard for lending me his boring head, cutters to suit, and an internal mic to measure the bore with. Couldn't have done it without them. :thumbup: - Bob aka krv3000 for kindly donating a valve cutting tool to the job (at least, I hope I understood correctly & that it was now donated.... if not, I owe you a new body, you'll see why in a minute). Another :thumbup: due. So, on with the show. First up, I cut a test bore in some aluminium. The aim, to hit the exact dimension + 1 thou, of the seat insert: It was a bugger to get in there, but once in & seated, it revolved easily. Mission accomplished :D Filled with an entirely misplaced sense of optimisim, I put the head back on the mill, reset the boring head & got cutting. I took a fairly shallow initial cut of 0.050", figuring I'd want at least 0.100", and preferably a bit more if I could get it. So... I merrily made a few cuts, then measured; AARGH, 0.005" over!!! Nightmare. Not to be dissuaded, I took another set of cuts, as deep as I dared (about another 0.075"), being much more careful this time. I got to within a thou and a half, & decided to go for the interference fit. Anyway, long story short, it didn't work, and I ended up with a cracked valve seat insert. So, plan B (again, thanks to Bogs for suggesting this one). I drilled 3x 5mm holes, plug-tapped them M6, and inserted small bits of M6 threaded bar, with a screwdriver slot hacksawed in the top. The result is this: The valve seat is still a good tight fit (in the bit I didn't overcut), and the three screws lock it solidly in place. I then milled the screws flat, and set about cutting the valve seat to shape/size. After using the hand operated valve cutter, as supplied by Bob, for about 5 mins, it became clear that this was going to take an eternity.... so, I modified the body of the tool on the lathe to fit a collet, then I could machine mount it. With the mill in back gear @ 67rpm, the valve cutter made short work of the job. After a couple more goes, I'd got it ground down nicely: The exhaust valve (with the slot in it) sits about 0.005" further out of the head than the inlet valve; that shouldn't cause any problems on this engine: And the fantastic valve grinding tool (with modified handle and home-made brass valve guide): The head has gone back to the customer (luckily I persuaded him to lap in the valves, a job I hate with a passion), will bring news of its working (or not) as & when. So, with that job out of the way, the time has come to pack the machine shop up & move it to its new home. Fortunately, that's just down the road, because having loaded a few bits of kit in the back of the car, I did rather worry for the suspension....: Glad I'm not moving the machines in the car!! |
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