K series cam timing

[AlfaSpider]

I'm after some advice on my cambelt change I've carried out on a 1.8 non vvc. All went well except now with a new belt fitted the crank timing mark is about 5 degrees BTDC more than it should be with cam markings aligned! It's less than half a tooth out should I worry as it runs fine?
Have fitted new water pump also so perhaps could be the diameter of this pulley is slightly different perhaps.

[DVandrews]

There is often a lot of slack in the bottom pulley fit to the crank, this can cause some misalignment in the marks.

Turn the crank to 90BTDC and see how close the timing marks in the pullies are, if they are less than a tooth out then this indicates correct timing but some slack in the system taken up when the crank pulley was refitted.

The water pump pulley is in the non drive side of the system so cannot affect the relative rotational positions of the crank and pulleys.


Dave

[AlfaSpider]

Thanks Dave. With the crank set at 90 BTDC the inlet and exhaust markings are roughly half a tooth from lining up, if I then turn the crank to about 95 BTDC there spot on and the locking tool fits. I've also tried backing off the crank pulley bolt and taking up the slack towards TDC, the two marks on the cam drive to pump housing are also out with cams aligned.
Would 5 degrees advance have much affect do you think?
As long as there's no risk of piston to valve contact i'll give it a run up the road see what its like.

[DVandrews]

The chances are that the crank pulley marker isn't actually exactly at 90BTDC anyway, I would remove plugs one and two to validate that the two pistons are actually level when the marker is at 90BTDC, you may find it is out by a considerable margin. I would then use piston height to determine 90BTDC, make a note of the innacuracy and then see how the pulleys align when the pistons are level....

Dave

[AlfaSpider]

With pistons set dead 90tdc I'm left with less than half a tooth out, is this just normal and only vernier pulleys would solve the problem?

[oakdale]

AlfaSpider said:

With pistons set dead 90tdc I'm left with less than half a tooth out, is this just normal and only vernier pulleys would solve the problem?

You've got something wrong here, in your photo the cam wheel on the right should show the word exhaust the right way up by the timing mark and the left one should show in.

[oakdale]

Unless the photo is the wrong way up, in which case the alighnment is o/k.

[DVandrews]

No, that is correct.. , there will be two possible positions for sprockets when the engine is at 90BTDC since it is a 4 stroke engine. There is a little misalignment but nothing to worry about.

Dave

[oakdale]

DVandrews said:

No, that is correct.. , there will be two possible positions for sprockets when the engine is at 90BTDC since it is a 4 stroke engine. There is a little misalignment but nothing to worry about.

Dave

I concur,but it does seem a funny way of going about timing the engine.

I would rather see the alignment a bit out the other way, so that as the belt beds in the marks would tend to go to where they should be.

[AlfaSpider]

Yes your correct the picture is the wrong way up.
Took the car for a run and all is ok. Thanks for the advice, the timing mark on the crank was out a couple of degrees with the pistons 90btdc.

[oakdale]

AlfaSpider said:

Yes your correct the picture is the wrong way up.
Took the car for a run and all is ok. Thanks for the advice, the timing mark on the crank was out a couple of degrees with the pistons 90btdc.

I thought it looked a bit odd.

This now puts the slight misalignment where I would expect it to be with a new belt, now it has been run and the belt has bed in, I'm sure the alignment of the marks will be near spot on.

[DVandrews]

oakdale said:

I thought it looked a bit odd.

This now puts the slight misalignment where I would expect it to be with a new belt, now it has been run and the belt has bed in, I'm sure the alignment of the marks will be near spot on.

With respect, that is completely wrong, the pulleys when viewed the right way up show both pulleys retarded by around 4 degrees. As the belt wears in, the difference in timing will be negligible but will increase the retardation rather than reduce it.

Most K series end up between 4 and 6 degrees retarded on the cam timing. I normally correct this with 6 degree offset dowels.

Dave

[AlfaSpider]

Are the offset dowels something you can supply? Cams will have to come out at some stage soon to rectify noisy tappets.

[DVandrews]

Err. Yes, but it wasnt a sales pitch.. Best conduct any dialogue via private message

Dave