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Timing chain tensioner fun
- Thread starter jonbills
- Start date
Alphabettispaghetti
Club Member
Its not so much of an issue as he's using the fancy tensioner, as long as the wipe patter/geometry is still good.
Thats the way I understand it as someone who has only ever pulled a 240z engine to bits
Its not so much of an issue as he's using the fancy tensioner, as long as the wipe patter/geometry is still good.
Thats the way I understand it as someone who has only ever pulled a 240z engine to bits
The tensioner surely only affects the 'slack' side of the chain so yes in theory the towers need raising to get the distance between crank and cam back to design and hence cam timing.
If you use an adjustable cam sprocket then the distance is not so critical because the cam/sprocket relationship is not fixed.
Alphabettispaghetti
Club Member
I'd guess he has one?
Albrecht
Well-Known Forum User
I don't think you've quite got the hang of this yet....
Albrecht
Well-Known Forum User
My point being that one of the very great benefits of the Kameari 'Twin Idler' cam chain tensioner is that you don't have to* shim the cam towers any more.
Cam timing isn't dependant on the distance between the cam and the crankshaft. Correct cam chain tension is, with the OEM cam chain tensioning system. The KEW Twin Idler system cures this.
Correct ( individual ) cam timing - as has been pointed out - is best achieved with a vernier cam sprocket.
*you still can, if you want.
Cam timing isn't dependant on the distance between the cam and the crankshaft. Correct cam chain tension is, with the OEM cam chain tensioning system. The KEW Twin Idler system cures this.
Correct ( individual ) cam timing - as has been pointed out - is best achieved with a vernier cam sprocket.
*you still can, if you want.
richiep
Club Member
As Albrecht notes, one of actual marketed features of the Kameari Twin idler setup is that it removes the need to use shims because of its degree of adjustability. See under "product specs - features" here:
http://www.rhdjapan.com/kameari-l-type-twin-idler-gear.html
Nice price too at £280 (plus shipping etc) given the recent weakening of the yen. One of these on my shopping list for the 3.1 stroker.
http://www.rhdjapan.com/kameari-l-type-twin-idler-gear.html
Nice price too at £280 (plus shipping etc) given the recent weakening of the yen. One of these on my shopping list for the 3.1 stroker.
I haven't got a vernier cam sprocket at the mo - I'm waiting on Kent to tell me the timing info for my cam. Then I'll see how close I can get with the standard sprocket.
My thinking is that I should be able to get close - by my calc, each link of the chain represents about 3.3 degrees on the crank (360/110), so I should be able to get that close at least.
Franky, I don't think skimming the head affects the wipe pattern - it'd only be a factor if I skimmed the top of the head too. (or indeed, if I fit cam tower shims)
My thinking is that I should be able to get close - by my calc, each link of the chain represents about 3.3 degrees on the crank (360/110), so I should be able to get that close at least.
Franky, I don't think skimming the head affects the wipe pattern - it'd only be a factor if I skimmed the top of the head too. (or indeed, if I fit cam tower shims)
Alphabettispaghetti
Club Member
It'd be a good time to fit a fully adjustable one?
Alphabettispaghetti
Club Member
Thanks to Alan, I've saved a fair few £££ by him pointing out the exchange rate was moving in our direction.
Obviously its just a shopping list of stuff I'd likebut its come down by a huge % in total. On the flip side it just makes the list longer too.
Huw
Club Member
What cam are you running by the way? If its a DII Fast Road the info for the cam is:
Cam lift .302"
Duration 290 degrees inlet 270 exhaust
Power band 2000-6000
Valve clearance .008" inlet .010" exhaust (cold)
Valve timing 35/75 65/25
Ok right I've had a 'proper' look at this now from various sites. My mistake, I didn't realise that it ran the 'pulled' side of the chain over a gear and you effectively lengthen the 'pulled' run by adjusting the top idler inwards until you acheive the timing.
Good bit of kit.
Hi Rob, no the tensioner still works on the slack side - even without the kameari kit, there's no real dependency between cam timing and distance between crank and cam. The bright links and timing marks are just a short cut for timing the standard cam.
Jon, there are two pulley wheels - one for tension (to replace the standard set-up) and one at the top (under the cam sprocket) to pull the chain in on the other side to alter the length of the run from crank to cam.
Normally if you skim a block or head by a significant amount (not just a clean-up) you have to re-time the cam. I've done it on an Imp using a special sprocket and dial guage.
Think about it, if the head is skimmed by 30 thou of an inch the chain will be 30 thou too long so the sprocket will lag behind the correct timing position.
I know the twin idler has two pulleys, I've seen one somewhere recently
BUT - like I said before, both idle wheels go on the slack side - one at the top and one at the bottom.
Maybe we're talking at cross purposes - I'm not disputing that skimming the head will rotate the cam sprocket counter-clockwise relative to the crank.
What I'm disputing is that one needs cam tower shims to correct it. As you said, you just re-time the cam.
Given a link is 3.3 deg, and the 3 sprocket positions give 4 deg adjustment, then I think I can advance with the standard kit 0.7 deg, 2.6 deg, 3.3 deg, 4 deg etc. If that isn't enough, then I can get a vernier cam sprocket.
