Aftermarket cam timing...

Wootie wrote: So back to the dot on the exhaust sprocket...any idea what the correct position should be for that?

Already explained that in the last reply.
In a perfect world it would be exactly level with top of the head ( cam cover gasket face) but due to camchain stretch , head/base gasket thickness , deck height etc they never are and it will be slightly above or below ( usually above).

Sorry Zed...I blundered through there without full cognitive powers activated. Thanks!

...they never are and it will be slightly above or below ( usually above).

Particularly if the head has been skimmed .

That 'a bit above or below' the gasket face variance could be a link difference - seems too uncertain to me with slotted sprockets.
Would it be possible to dial it in accurately but have the dots looking to be in the wrong place - or worse have the dots looking in the right place but not dialed in right?

Dialing - in would also give you a cam spec in lift and duration which could give you a clue as to what grind you have. In the absence of any info then setting 105 or 110 lobe centres would be a good start.

I might be being a drama queen here, just seems an element of risk as maybe it could look right but be a tooth out?

If no info on cams then set at 110 deg lobe centres to start.
If the dot was a tooth out above or below (which would mean the sprocket was a tooth out on the chain) it would be visually obvious with the next (correct) camchain pin being closer to the gasket face than the one being observed.
Slots in professionally produced ( not home slotted ) sprockets give adjustment within the range of 1 tooth so as long as timing marks are correct the timing cannot be more than a full tooth out.
When degreeing you set up the timing with the marks correctly aligned first then adjust the cam within the range of the slots so the marks will always be correct when the timing is .
Obviously if the degreeing wasn't done correct initially then the marks could be correct but the timing wrong but that would be in relation to the cam grind specs and not tooth count.
If the timing marks were not correctly set then it would be near impossible to get the degree figures required without running out of or pushing the cam to the limit of the slot adjustment and if that were the case the error would be glaringly apparent and the person doing the job should not be attempting the procedure and hand it over to a competent mechanic.
In this case the cam and sprocket orientation hasn't been disturbed, so yes. I agree ! you are indeed being a drama queen and adding unnecessary complication to what was originally a simple query.

So there is 'only' 1 tooth worth of slot adjustment either side. ok then , 'only' 45 degrees of crank rotation between extremes for each cam then? (720 degrees over 32 teeth) Too many unknowns and assumptions here for me.


If the timing marks were not correctly set then it would be near impossible to get the degree figures required without running out of or pushing the cam to the limit of the slot adjustment and if that were the case the error would be glaringly apparent and the person doing the job should not be attempting the procedure and hand it over to a competent mechanic

Maybe the person here is a new member who didn't quite grasp the significance of taking notes or digital pics of the timing marks during the stripdown. I suggest a competent mechanic with expereince of slotted cams and valve timing wouldn't need to ask this, therefore what may be glaringly obvious to you might not be to him..

so yes. I agree ! you are indeed being a drama queen and adding unnecessary complication to what was originally a simple query.

Don't be a clever cunt. A bunch of bent valves can be pretty dramatic too. Cam timing isn't a simple simple question.

Tyrell Corp wrote: So there is 'only' 1 tooth worth of slot adjustment either side. ok then , 'only' 45 degrees of crank rotation between extremes for each cam then? (720 degrees over 32 teeth) Too many unknowns and assumptions here for me.


If the timing marks were not correctly set then it would be near impossible to get the degree figures required without running out of or pushing the cam to the limit of the slot adjustment and if that were the case the error would be glaringly apparent and the person doing the job should not be attempting the procedure and hand it over to a competent mechanic

Maybe the person here is a new member who didn't quite grasp the significance of taking notes or digital pics of the timing marks during the stripdown. I suggest a competent mechanic with expereince of slotted cams and valve timing wouldn't need to ask this, therefore what may be glaringly obvious to you might not be to him..

so yes. I agree ! you are indeed being a drama queen and adding unnecessary complication to what was originally a simple query.

Don't be a clever cunt. A bunch of bent valves can be pretty dramatic too. Cam timing isn't a simple simple question.

Not being a clever cunt mate but apparently neither are you ( well not a clever one as your attitude reflects ).
I didn't say one tooth out either side I said within the range of one tooth.
360 degrees over 32 teeth equals 11.2 degrees of cam per tooth ( or 12 degrees if its the 30 teeth cam sprockets) or double (22.4) that for the crank.
The error of one tooth is 360 divided by 32 which is 11.2 degrees if it were a full tooth out on the sprocket.
So if the correct timing happened to be exactly in the middle of the slot it could only be HALF a tooth out ( 5.6 degrees) if pushed to the end of the slots.

And as for a simple question, the guy only asked if the dot was the timing mark PERIOD, and in none of his subsequent posts does he ask about degreeing . Should seem very SIMPLE to most people.

I have a remarkably stupid question to ask...working on a KZ1000 motor with a big bore kit and such, and with aftermarket cams.

The OEM exhaust cam would have a small horizontal line on the exhaust cam sprocket that you were supposed to get level with the top of the case - generally with the line itself being just a bit above it. The aftermarket cam just has a dot though...so my question is is that dot supposed to be where the line would be...like, a little above the case, or should that dot be center-on at the edge of the case?

Thanks for any help!

He hasn't disturbed the cams on the sprockets so why start bleating on about cam degreeing and the dangers of miss timed cams when it's just a simple job of refitting the cam on the marks.
Like I said.
Unnecessary complication.

Looks to me like about one tooth either side range of adjustment, so between extremes there about 22.4 degrees cam time, 44 degrees crank rotation ...on each cam.

Even 'only' 4.5 degrees out - or 9 degrees of the crank rotation seems an unacceptably high margin of error. That is assuming it was set exactly on time to start with.



Added to that other minor details like:

whether OP's new big bore piston valve cut out pockets are deep enough

what the cam spec is , lift and recommended clearances and oil spec

whether the cams ware timed correctly / conventionally in the first place,


Simple minded it may seem to some, but far too many assumptions and uncertainties for me here.