Timing belt one tooth out

I recently purchased a TF as a winter tinkering project and currently have the engine in the garage for some TLC. On checking the timing belt before removing the head I found that the belt is one tooth out with reference to the two dimples on the inner crank pulley. Whilst I had the car on the road the engine seemed to be running very smoothly except for a tendency to pink if the revs got too low and hunting a low revs. Would you expect an engine to run so well with the timing out. Did the previous owner know something I don't or do I just add it to the list of horrors already found.. See attached pictures.

Engines can still run what seems to be reasonably well......older engines could be advanced or retarded manually.......but more modern engines are controlled electronically causing them to hunt has the computer struggles to find its best position........but damage to engines can bite you in the but by having incorrect timing has it can cause excessive combustion temperatures.........faulty...iacv can also cause hunting.........when i fitted my cambelt,,,,, i accuratly locked the crank into position with the crank pulley removed......i used a locking tool on the flywheel.and alighned the crank timing markwith the marker on oilpump.......and used the proper locking tool on the cam gears......its important to get right.......and one of the hardest parts of doing the cambelt is getting that engine cover off.....garages love charging you for that pleasure.
tools i used below....some mechanics may fit a belt without them....but using the correct tools makes it fool proof they rule out getting the belt wrong.....and even when the marks are alighned correctly....it is very important the belt is then fitted tightly working around in a anti clockwise position....feeding the belt from the crank first and then keeping it tight..and after tensioning the belt then turn the engine manually by hand at least twice and checking again...once you have done the belt yourself you will wonder what all the fuss was about.it is easy to get that belt of yours timed correctly has your almost there gears exposed and engine cover off etc
older none elecronic engines could be commonly found with one tooth out on the timing....has mechanics struggle to tune a badly worn engine...they could result to drastic measure by altering timing gears to get a compromise.......a cost cutting excercise to refrain from spending money

You need this exciting new ladybird book.



Other exciting releases include these.

or has andy suggests get yourself one of those ladybird books......just like those we read at school and totally destroyed a normal childhood

Hi Campsie
I had hunting problems with my TF and although Russell had checked the engine a few times and I had replaced all the normal items he eventually found that although the cam wheels were aligned the pin locating the wheels to the cam was flatened thus giving the hunting problem. Changed the pin and all is now well. So if you are checking I suggest you remove wheels and check the pin.
Cheers Brian

found the ladybird book :coat:

You don't say whether this engine is a MPI or a VVC.
So assuming this is a MPI.

One tooth out won't be the end of the world!
It's possible that the one tooth out was done intentionally, in order to possibly gain some perceived performance advantage.
Whether or not this was achieved, I couldn't say.
I may just be an attempt in trying to get VVC like power from a MPI.

I'd done the same thing to my old 105 series Alfa Romeo GTV 2000.
It didn't idle so good and could be grumpy at low revs :rant: , but the thing would go like the clappers once it got "on cam" and would rev way beyond the red line (in fact right off the tacho) :omg:
It was a pain in the arse in traffic, but shitloads of fun on a mountain pass :drive:
These old Alfa engines had dialed cam sprockets so as they could be indexed for this very purpose.

The idea is that the difference in the phasing of the inlet and the exhaust valves could be advantageous to performance in certain circumstances.
The phasing chosen by the original designers would've been a compromise between performance and other factors such as emissions, smooth idle, fuel economy, ease of drivability etc.
These other factors may not have had such a high priority with whoever installed the belt.

Of course the VVC engine varies it's own valve phasing automatically to achieve this.

The other scenario is that whoever installed the belt was an incompetent oath with more mechanical ineptitude than aptitude! :lol:

So I'd set it up to standard spec and go from there.

Fixed valve/cam timing on a petrol engine with a wide rev range is only a compromise and the standard valve timing will be too advanced at idle and too retarded at max RPM but somewhere in the mid RPM range it will be spot on. On a K series the ignition timing will not be affected as the pick-up signal is from a pulse transducer with a reference from drilled segments in the flywheel and not from the cam sensor.

I can see by your images the engine is an MPI (non VVC) the valve/cam timing being one tooth out on the crank pulley is only 7.5 degrees out on the cams (crank pulley 24t, crank to cam ratio 2:1 -: 360/24/2=7.5) and when you look at the VVC engine the valve/cam range is adjusted over a 37 degree range.

When fitting a timing belt and you set the pulleys in the correct position it’s not always possible to get the timing marks spot on in relation to the teeth on the belt, some engine manufactures have a vernier setting on the cam sprockets so you can get the timing marks in relation to the timing belt spot on, whereas on the K series the cam sprocket to cam location is fixed by hollow dowels.

I can see the valve timing being out by one tooth on a petrol engine and still allowing the engine to run; albeit not correctly. This is only because on a petrol engine there is quite a large compression space allowing piston to valve overlap, but one tooth out on a diesel engine would definitely have piston to valve contact.

As mentioned in one of the posts above check the hollow dowels on the cam sprockets, when I was refurbing my head it looks like the cam sprocket bolts had been tightened by locking or holding the cams which distorted the dowels, make sure when you torque the sprocket bolts back up you do it by locking the sprockets not the cams or you will twist/distort the dowels.

It will be interesting if you notice any difference in performance when you have re-set the timing correctly.

Brian.

Perhaps we need a Ladybird book of botches. Thanks for the reassurances. I'll set the cam back to where the designers intended it to be. Hopefully that's the last of the horrors I will find. The worst one has been the welded on nut on the suspension bolt which fell off when I touched it with a spanner. That and stripped threads packed out with washers but I think that will need a new post.

Ah Ladybird books, brings back good memorie, although my parents never brough those particular books home for me, I don't remember those titles...

I wonder if this is why Felix is lumpy and hunting despite a plethora of changed parts? When it stops this horrid weather I'll whip the cam cover off and check.

If being one tooth out gives me a performance boost mine can stay that way . I spoke to Jon Norris a while ago about some other issues and mentioned the uneven idle my TF has his reply was the timing being slightly out. My TF runs perfect and on tick over sound a bit like a Subaru , and also goes like one as I was quite surprised when I had a head to head with a skoda Fabia vrs yesterday. Only mods to her is an mgoc supersports exhaust and a piper cross panel filter, oh and one tooth out I guess.


:beer: :beer: Steve