griff851
The 748 throttle bodies arrived yesterday. For those that may be interested they have a few design differences. For a start the lower hole is 44mm not 45 mm as with the 851 bodies. They can be bored out. Also so the bit that the velocity stack sits in is 7mm shorter to the ledge that the velocity stack sits on and is also 3.5mm wider. An O ring will fix that, and an extra 7mm of velocity stack will make minimum increase in torque. It will help the top of the velocity stack clear my air filter rubber mount (using Uni filters), so that's all good. The injector plugs and TPI plug will plug straight on. I will be taking the 748 mounting rails off and putting on my 851 ones as my pressure reg and reversion valve sit on the 851 rails.
The fuel lines will have to redesigned as a single fuel line goes into the 748 injector, unlike the 851 which has the cap with "T" setup for return fuel.
Griff
loony888
what? no airbox griff?
griff851
Yes Paul, the C/F 3 piece one I've always had.
Griff
loony888
griff851 wroteYes Paul, the C/F 3 piece one I've always had.
Griff
ahh ok, you said uni filters though, are you going to run separate pods in the airbox? will they fit? i run a jhp hat type (916) foam filter in mine and it only just fits.
paul.
griff851
griff851
Well today was rod and crank day. It started off bad. I thought that the free float was about 0.28mm + 0.03 for triple bond. Just to make sure I used a screw driver between the crank and the case, as opposed to just grabbing the shaft by hand, as with the gear box. With a fair bit of force the free float turned out to be 0.88mm. So I spent some time grinding down two 0.5 shims down to 0.485, giving me a nice crush of 0.1mm, the book says 0.15mm but I think thats a bit much.
Next the the conrod BE bearings. I have Corrillo "A" rods on a "B" crank. Using flexigauge with 998 red shells I have a very nice 0.025mm clearance between the shells and the journal. Unfortunately the journal has very light scoring, so I sent it off to be polished with instructions not to remove any more than 0.004mm, so that should give me a nice 0.030 clearance.
Griff
PS since writing this I have decided to go for 0.08 crush on the crank, so more grinding to be done.
griff851
Just for reference.
Measuring bearing shells with a micrometer is rubbish. Today I was getting 1.445 on the 998 red shells, yet the flexi gauge said they were 0.148. Monster shells I was getting 1.65
916 shells (from the book. A lot of the manuals don't tell you the size of shells) are as follows to give the size range between Red and Blue. I was getting
Red 1.482- 1.487
Blue 1.486- 1.491
According to the Porsche boys, the general effect of the nitride goes down 0.5 mm hence the first grind is half way at 0.25mm To me it means you can grind 0.127 then polish with out too much drama other than bearing sizes. You can get coatings for bearing shells that can be applied up to 0.05 thick.
As mentioned earlier by Steve, VW Polo shells can be used.
Griff
griff851
Todays entry is as boring as hell. The Crank shims have now been ground down to 0.48mm (0.0188". I found a standard to calibrate my dial verniers) giving a crush (preload) of 0.077mm in theory. Crank is back with 0.004 material removed during polishing with the belt method and surface now perfect.
Griff
marvin
griff851 wroteTodays entry is as boring as hell. The Crank shims have now been ground down to 0.48mm (0.0188". I found a standard to calibrate my dial verniers) giving a crush (preload) of 0.077mm in theory. Crank is back with 0.004 material removed during polishing with the belt method and surface now perfect.
Griff
Griff,
Are you sure that .077 is enough preload? I was told by a well known engine builder here in the us to use .1mm (.004") with used bearings, .15MM (.006") with new bearings. They are angular contact bearings and depend on preload. I set mine at .1 with used bearings and 20k miles later still fine. There is a long thread about preload on Speedzilla. Ducati now calls for lots more preload, don't know why, seems as though nobody else does either!
link:
http://www.speedzilla.com/forums/ducati-superbikes/52252-749s-crank-preload-stalling-story.html
griff851
Yes well I may have gone over board here, guess thats why I post everything. We had a group discussion the other week about preload. Bob was a pro 0.1mm sighting that he had pulled apart an engine a while ago that he had set at 0.15 and after 30,000km it was still fairly firm. I just thought well why not split the difference between a roller (which would be 0.0 when hot) and the angular contact bearing, thus ending up with a free spinning crank. After reading the bit about hot water from Brad in the speedzilla now I'm not sure. Of coarse that would imply that a SP5 crank when hot would then be floating, and that doesn't sound right. I guess I should run with common consensus and set at .1mm, that would be the safe thing to do. Mmmm time to read up on maximum and minimum loading on angular contact bearings. I would have thought that minimum loading would be the go.
The book does say that the idea of preload is to seat the bearings.
Griff
griff851
Ok I've read a burst on preload. Too little and the ball can skid, causing vibration and wear. Too much and rotational performance drops off (Crank too tight and won't rev freely) and of coarse increased wear on bearing surface. I'm now going to contact a bearing engineering mob to see what they have to say and maybe suggest the ideal preload.
Griff
marvin
Geez Griff,
I bet it would still be fairly firm if he set it at 1.5 !😯
griff851
😁 typo. 0.15
Griff
griff851
Well clock one up to dumb arse luck. I took the shims to the shop and measured with the micrometer. Bang on 0.49mm on both. I definitely think my calipers have had their day. Send donations to :- Get Griffy a new set of Calipers for Christmas fund. 😄
Griff
griff851
I've just installed a Super zoomer 5000 transmutation kit. When I ordered it online they said it would speed up engine rebuilds a 10,000 fold. 😁
Its an animated gif.
Phil911
griff851 wroteI've just installed a Super zoomer 5000 transmutation kit. When I ordered it online they said it would speed up engine rebuilds a 10,000 fold. 😁
Its an animated gif.
---> Oooouuuhhhhh, hot wheels !!!!!!!!!! 😁
Phil911
griff851
Todays hassle. Corrillo genuine bolts are going to set me back AU$340 for 4. I can get 8 aftermarket ones (same spec. SPS 55's with 5/16 thread) for AU$180. Anyone in the US need 4 new bolts if I buy them?
You can torque Corrillo bolts 3 times before you have to bin them.
Griff
Ken L
Are you sure about that price?! I only paid $600 Canadian for two Carillo rods including shipping. Can't believe the bolts would cost that much!
Oh, yeah,... .015" preload is what I set all the Quattro engines with stock brgs to that I build at our dealership here.
Ken.
brad black
the carrillo bolts should be fine as long as they come up to torque within the specified stretch. it's usually only once you go over the stretch for given torque that you have to throw them away.
see if pete smith at epicycle has any.
griff851
Thanks Brad. That price and info was from show and go.
Griff
