Camshaft Timing After Head Skim: Late '89 1.6 Cti

[lagonda 42]

Been so busy here & the CTi has run so well since I rebuilt the engine (2007) that I've neglected all maintenance etc!

 

I realise this is wrong & asking for trouble....that was over 41,000 miles ago & I think the recommended cam belt change interval is 36,000.

 

So, once I've checked I have a spare one, I'm going to start on it today.

 

My original head was cracked, so QEP sold me a good one, actually from a 1.9 so has 1.9 cam (the original 1.6 cam was badly worn). They skimmed it of course; I asked them only to take enough off to bring it up to dead flat, but of course it could have been skimmed previously.

 

I've done a search & it seems a mild skim has little effect on altering the cam wheel/crank sprocket position, so the timing pins should go in their holes as standard. But mine didn't.

 

So, two questions!

 

1/ Is it usually the case that a 1.9 cam in a 1.9 head on a 1.6 block will mean the timing pins not lining up?

 

2/ I don't want the hassle of sourcing & fitting a vernier pulley, so my only option is to retard, or advance, the timing slightly, by fitting the belt to a position either side of the point where the pins do line up...so which should I opt for? I realise the ignition timing is affected as well, but can at least adjust that if necessary.

 

When I rebuilt the engine, I didn't have time to go into niceties like this, but would like the best setting now I'm doing the job again. Petrol consumption has been fine...often 38mpg, & I've seen 41 once! But I've never really been happy the performance is as good as I expected. I realise that's a common observation with these cars; my cousin's car did drive as fast as I expected the CTi to be, but his is a 400bhp Lotus so I've had to accept I'm expecting too much!

[lagonda 42]

Anyone any thoughts on this?!

 

I've found the new belt so started dismantling; would be great to have an expert view soon so I can assemble accordingly.

[welshpug 1,657]

1) all parts are the same in fitment, no issues whatsoever.

 

2) the pins will fit just fine but place the front of the belt a tad looser than it should be till you remove the pins, then they will retard a couple of degrees, unsure how much though as I haven't seen one myself.

 

moving the sprocket a few teeth will be far too much, 1 tooth IIRC is 8.5 degrees!

 

 

Personally I would get hold of a vernier, they are easy to find, or you can make your own by taking a later XU 16v pulley, getting it made narrower then fitting a 2mm thick shim behind it.

 

http://forum.205gtid...1

 

As it its a 1.6 as well, I would use a 1.6 or an aftermarket cam as a 1.9 will make it feel lazy, I remember Goliath having a dog slow Miami 1.6 that had a 1.9 top end dropped on (the head is the same, only the cam differs)

 

it would hardly pull 60 up Crickley hill in Gloucestershire, where his diesel 405 will be approaching triple figures!

Edited September 20, 2012 by welshpug

[petert 586]

After skimming the head, the only way to verify the cam timing is to measure the lift @ TDC, or the lobe centre line, then advance the cam as required. It can be done with an offset key if you have the machining skills, but a vernier is probably the easiest solution for you. We're talking about a quarter of a tooth, not a full tooth.

[lagonda 42]

Thanks for replies. 8.5 degrees is quite a lot, so I suppose my best bet is just to go for the nearest tooth, so to speak.

 

When I changed the head back in 2006/2007, most people were saying I'd hardly notice any difference between the two cams. The original cam was pretty knackered so I never knew how the car drove with a decent 1.6 cam.

[petert 586]

And that's 8.5 cam which is 17 deg crank. You'd need to move it around 4 deg crank.

[B1ack_Mi16 67]

Regarding the issues with timing holes not lining up after skim.

 

Not long ago I changed cambelt on my 407 2.0 HDi.

 

First I didn't understand why the slot in the cambelt crank pulley was almost twice the width of the woodruff key.

This HDi engine has two cams, but only one cam pulley and a chain between the two cams, so externally the timing gear is much like on an 8 valver XU.

 

The extra width of the slot in the pulley lets you position the cam pulley exactly where it is supposed to sit. The crank is locked/timed up by inserting a pin into the flywheel locking hole behind the starter motor. The bottom crank pulley will now fit independently of how much of a skim the head has got, as it is free to move quite a bit both ways. It's only held in place by friction, but as it is a factory set-up it still seem to be realible.

[lagonda 42]

Too busy to carry on with car yesterday, but I'm now at the stage where I'm ready to try the pins & see how they line up now; after all this, it wouldn't surprise me to find they line up now!

Petert: stop! You're making me more & more worried!

BlackMi16: that's interesting. It sounds like the sort of bodge I'd dream up & then decide against as too risky. I'd think first, what a good idea, then I'd think woodruff keys are used in situations where friction alone is insufficient. Here you have a pulley driving a cam, with all the shock loads entailed, & then driving yet another cam. Wonder if there's some special high friction surface they've used.

[woodsy 0]

I replaced a belt on a hdi motor other week and as said, the crank sprocket does have quite a bit of movement to take up slack. I thought something wasnt right at first but then realised.

[pug_ham 244 3 Cars]

How far out is it?

 

A minimal skim will change the timing very slightly but only by a fraction of the timing hole.

 

A friend used to run a 1.6 with 1.9 head & cam, even when I'd set the timing with a vernier it wasn't as snappy as the original all 1.6 engine but the car had done ~160k with dubious history.

 

Anything less than 5' timing change will apparently make no difference but I found this one felt to drive & definately ran better once correctly timed but not as nice as with the right cam.

 

I can't remember how many degrees off exactly but it wasn't more than 3' iirc.

 

g

[lagonda 42]

Well, what do you know, having gone into all this, I checked the timing pins & all lined up perfectly. So does the new one...so how come when I put that last belt on, things didn't line up?! Happy bunny now anyway.

I'm intrigued that after all, opinion now seems to be that the 1.6 cam would be noticeably better. The lobes on mine were seriously worn, a common problem apparently, with 1.6 cams.

So..is there a supplier of good 1.6 cams, or perhaps something sportier, that can be recommended?