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Double J
Denver,
USA
Posts: 101
Daytona 955i (99-01)
09 May 2008 01:38 |
Warped the head on my 99 955i, how much can I shave before things start smacking into each other?
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Kerry
foot of Mt Taranaki,
New Zealand
Posts: 81
Premier Member
Daytona 900 (93-96)
10 May 2008 12:40 |
Hi Double J, Though I have never had a Hinckley head 'planed', I don't think you could get more off than 0.30mm. As a rule of thumb, the minimum clearance between the valve and piston should be 2.04mm on the intake valve, and 2.54mm on the exhaust valve.
If you have a close look at the inlet valves when fitted to the head, you will note that an edge of the valve is virtually flush with the head face. The exhaust cam in your Daytona has a total lift of 6.89mm. So really not too much too spare. Someone else here may be able to be more accurate, but for piece of mind I would look around for a used head.
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Sam KS
Queensland,
Australia
Posts: 294
Daytona 955i (99-01)
10 May 2008 12:49 |
also the ally in the head could be kaput after getting so hot to warp the head. I'd rather try the breakers to find a replacement IMO.
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Double J
Denver,
USA
Posts: 101
Daytona 955i (99-01)
10 May 2008 17:39 |
I got a hold of my local Triumph/Duc shop (Erico's Ducati/Triumph in Denver, they neglected my 996 alot and it ended up costing me 3000 dollars to have it repaired by a real shop, don't go there) and they told me .010 inches was the max I could take off. My conversion math is bad, not sure if that's close to .3 mm or not, but we ended up taking .006 off and to my eye, it's so close to the intake valves I can't believe they didn't take a little shave too. I'm still waiting on my repair manual that I ordered so I can put it all back together and see what happens. Wish me luck.
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Sam KS
Queensland,
Australia
Posts: 294
Daytona 955i (99-01)
10 May 2008 22:24 |
OK just found a conversion table for you.
0.3 millimeter = 0.011 811 023 622 inch
0.01 inch = 0.254 millimeter
0.006 inch = 0.152 4 millimeter
i used this http://www.onlineconversion.com/length_common.htm as i have no idea about that funny imperial stuff. over here is OZ we only used that good old French system of metric when i was a lad, I don't know why some of the colonies still stick to the old British system. 
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Kerry
foot of Mt Taranaki,
New Zealand
Posts: 81
Premier Member
Daytona 900 (93-96)
10 May 2008 22:49 |
Hi Double J, that is correct. .010" is 0.27mm, I stated 0.30mm, so we're talking roughly the same language. And like I said, 0.30mm, though a very small amount, would be very close to those inlets.
0.006" is 0.16mm, so that's slightly over half of the 0.30mm. If the 0.16mm planing has cleaned up the face it should be perfectly ok as you have plenty of room to spare:)
Make sure you drop the valves out, as there's bound to be small particles of swarf in the valve springs from machining etc.
Also, re-lapping the valves would be a good idea to guarantee no gas leakage and the added benefit of minutely gaining some extra clearance.
Bearing in mind that the head had warped, chances are the valves will need re-lapping anyway, and possibly the seats may need recutting. This should be left to a shop with the correct cutting tools, as the seat angles are critical for a well performing engine.
A quick and simple test for leakage is to spray some Fuel/CRC 5.56/WD40 or equivilent into the exhaust and inlet ports, if the valves aren't sealing you will see the fluid seeping past the valve & seat. You will no doubt also have to re-shim the valve clearances too, especially if the seats are cut & reprofiled. And finally, while you're at it, replace the valve guide seals.
Wishing you luck:)
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Kerry
foot of Mt Taranaki,
New Zealand
Posts: 81
Premier Member
Daytona 900 (93-96)
10 May 2008 22:53 |
Sam got in while I was replying, his posted conversion is far more accurate than mine. I was roughly converting from my callipers
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Cerberus
Connecticut,
USA
Posts: 5,264
Premier Member
Enthusiast
12 May 2008 14:14 |
biggest problem is when the head warps, it warps the cam bearing saddles as well.. not so much an issue in some cases, but in the case of a cam run in the head(without bearing shells) i wouldn't want to do it..
best advice is find another head that hasn't warped or been cut and use it.
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