Dan Ingram

iTrader: (4)

I've spent the last 3 hours trying to time up my engine and I just cant seem to get it right. I line up all the pulleys in the right place, put the belt on so all the marks on the belt are at the right place on the pulleys and have all the slack where the tensioner is. Refit the bottom idler and remove the tensioner pin. Then when I spin the engine round twice all the marks line up apart from the two left hand pulleys. If I keep spinning the engine round they don't get any worse but they are always out. Its only one tooth out on each pulley but I want it right.

I'm using Ver5 STi heads on a Ver8 STi bottom end with the later type tensioner. I've had the heads skimmed but not much. With the headgaskets the compression ratio is 8.34:1.




Right hand pulleys lined up



Left hand pulleys way out







Any suggestions? I can't work it out and its really beginning to do my head in.

Motion-Mx

iTrader: (2)

looks about right to me? if it was another tooth over to the right,then it would still be way out...

r1c

iTrader: (9)

In pic 3, line up the belt and pulley with the notch in the cover, Do the marks in pic 4 line up then? If it turns over by hand with out locking up your not gonna harm anything, see how it runs, it does look ok to me too!

Dan Ingram

iTrader: (4)

Ok I've just been out and spun it round a couple of times. If I move the crank pulley round just slightly to here



I get the other 4 here









Are they close enough? Is it me just being a bit paranoid? I just like everything to be spot on. The crank seems to far out to me.

Slowboy Racing

Its fine, they are never pin perfect and can seem a tooth out. The most important thing is to line the crank sprocket correct and then the timing marks on the belt with the remaining pulleys as you have. Every turn after the first will send the belt marks further away from the corospnoind pulley marks, eventully they will come back into sink if your prepared to sit there winding the engine.

It all looks fine.

widdows

looks fine mate, I had the same dilemma 6 months ago and because I wasnt happy I stripped it all off and re did it several times with the same result every time. got sick in the end and decided to try it as it was (because I couldnt feel any mechanical jamming) and it ran perfectly!

FB Tuning

iTrader: (30)

As above, if you fit the belt with it's timing lines corresponding to all the correct marks on the pulleys then it can't be out (unless someone stamped the lines on the belt in the wrong place )

It's fairly common to see the pulleys slightly off their alignment marks, especially so on the crank pulley itself, if you've lined up all the cam pulley marks.

I've always been interested to know how far out the cam centrelines are in this scenario, but have never been bothered to to get the DTI out to check.

It's part of the reason why i run with vernier pulleys - to minimise the losses on a built motor that's had block and heads skimmed (more than once!)

ZEN Performance

You could move the idler pulleys within the slack the bolt allows to get rid of some of that discrepency. For instance the lower "half idler" (orange seal) loosen and move up, the toothed one move down, and the upper plain idler move down. It won't get you much but it might result in a 3-4 degrees at the cam pulley. The problem is you've skimmed the heads, perhaps the block and are using the Cosworth thin 2.0 gaskets so you've lost some width of the engine. Which will retard all the cams a little (left bank more so).

In reality it will make little difference.

Dan Ingram

iTrader: (4)

I've sorted it thanks for the replies everyone. I set them all up to the right marks on the belt then advanced the LH exhaust pulley one tooth. Its pretty much bang on now. As you said its down to the heads being skimmed. Ideally vernier pulleys would sort it completely but I can't really justify spending that much at the moment.

madscoob

iTrader: (3)

refit the belt with all marks lined up but secure passangerside pulleys in poistion with rubber covered mole grips . the refit tensioner and remove pin with mole grips still in place . the when under tension remove grips .. classic passanger side pulleys move half a notch as per your photos if not stopped from moving when tensioner is released

ZEN Performance

It doesn't matter what you do with the tensioner, they pulleys will end up half a tooth out again once the engine is turned over and the tensioner works as it's designed.

ZEN Performance

So are you saying that on one side of the engine you've advanced the exhaust cam by a tooth relative to the inlet? I would have left it as it was rather than unbalance the timing on one side of the engine. Remember what the cam timing really is, it's degrees of rotation, the marks are just a convenient tool for fitting the belt.

If you want it spot on without spending money, do what I did with my first built engine and cams, and that's to slot the notches on the cam wheels so you can rotate them relative to the cam a little. The WRC engines do not use dowels or keys to locate the pulleys relative to the cam, they just set the timing and do up the bolts!

Dan Ingram

iTrader: (4)

Yeah I've moved the exhaust one tooth round. It all lines up a lot better now. Notching out the pulley isn't a bad idea at all. I'll get it running first then see about doing that

FB Tuning

iTrader: (30)

Personally, I'd set it back up on the factory timing lines, if you intend to fit it 'as is'

If you want to notch the pulleys out, then you really need a DTI and degree wheel, so that you can set the cam lobe centrelines in exactly the correct position - You'd be better off doing this before you fit and run the motor, because you need to have the motor out to accurately degree them in.

I don't know what the centrelines should be on STi5 heads (maybe 110/110) - perhaps Zen can help with this information?