Hi all, Take a look at the attached pictures, I would like your opinions on the cam lobe position. In all the write ups I have read the cam positions are as my pictured horizontal cylinder, the center of the two cams form a line across the head. Now look at my vertical cylinder. The cams do not seem to be in line. Is this normal? The cams are in the exact same position as when the belts came off. Again every write up I have found the cams look to be inline across the center.
Its the correct position for cams pre 2009. 2009 and on the vertical has the same pattern as your horisontal, that is the 'legs' of the T-shaped cam material is in line with the bore and pointing up. Should anyone be uncertain what cams are in there the vertical intake will have max lift (standing on the lobe fully open) when driving pulley is aligned to the case marking.
Ah ha brilliant thanks matey. The outgoing belts were very loose IMO as when fitted the cams could be turned slightly. Could a loose belt affect idle?
Having spent an evening dialling in my cam timing. Here is a photo of how mine look. Bear in mind I'm not running std timing. ( but close enough for a visual comparison). Hth
No problem with that no. Dial the cams radically and the two wont align perfectly on the same cylinder agreed, however try a full tooth off for shits a and giggles and youll see its too much anyway.
Brad Black timing spec of 108 inlet. 113 exhaust (it's a 749s) Cam centre line measured at 1mm lift. Some bloke called Stu posted them to me and very promptly too.:sunglasses:
Bearing in mind this was a total strip and rebuild. So the pulleys were disassembled. I fitted a degree wheel to each cam and measured the angle at 1 mm opening and 1mm from closed. Divide the result by 2. Finding the cam centre line. Belts on with the cams roughly where you would expect them. Degree wheel on the crank. Wind it round to desired angle, align cam to centre line which you've pre marked. Lock the vernier pulley bolts. Bingo! Repeat for rest of them. I double checked the expected open and closing angles and job done.
Im humble to this as I know the effort, good job! For the 749S I have no clue to why its recommended with less overlap? Perhaps the stalling part. For the big bangers I do a lot of overlap and if you dont increase ignition timing at idle they WILL stall, so you need to now how to go about it yes.
New belts fitted and engine started, thanks @Exige Checked them using a phone app for guitar tuning and a double check with a 45 degree twist, exactfit belts came with an instruction to tension to 99 hertz NOT 110 as stated for ducati belts, I guess they are a more dense belt. All seems well so far, torqued the pulley nuts to 18 ft lbs following info found in my service manual that I downloaded (says 25 NM which I converted to 18 ft lbs)
The new belts sound very different to the outgoing belts so I guess this may be because they are new? I've been out for a ride to get up to working temperature and then came home again to double check my work. I have removed the belt covers and everything looks as I left it. The tension feels good still so it must be the nature of the new exactfit belts.
They have a rubber coating over the teeth profiles unlike the OEM belts so will be a little different in sound, should bed in after a while - let me know how you go
My ExactFit belts sounded no different to oem. These engines have a 'top-hat'spacer on the adjustment pulley which has to be seated correctly. Take a look at this: Testastretta Cam Belt Tensioners
Thanks, I'll take another look at it just to be sure. I did remove the covers again after 20 miles or so and the belts still looked new. Edit: Also the belts I removed were loose as F##k
Interesting, just goes to show how important it to inspect them regularly. I'm sure you won't have checked the frequency for the loose belts but it might have been useful to know just how loose they were...
No didn't check the frequency but they were loose enough to simply slip off the pulleys by hand easily.
