Shiming Cams

[Mike Walker 0]

Hi guys,

 

Recently bought this:

 

 

Loving it so far, just a few minor issues. and questions.

 

It has a 1.9 lump in it mated to the 1.6 gearbox. The head on the engine was reconditioned before it went in but I believe the cams were shimed up incorrectly, it also has a blowing manifold gasket.

 

I'll probably change the gasket myself but i'll get the cams shimmed up by a mechanic so i'm wondering how long this should take/how much it should cost to be done?

 

I'm also looking for advice on the quality of the standard 1.6 seats around a track as I have an OMP composite seat from my old car sitting around but i'd rather keep the 205 as standard as possible (as I love it that way) although it is going to be used on track maybe once a month.

 

Any help much appreciated

[ALEX 98 1 Cars]

Shimming up the Cam is a pain in the arse, as the timing belt has to come off and the cam has to come out.

Checking them is easy though.

All you need is a set of feeler gauges.

[Pug_101 0]

Not sure this can be done on the Peugeot, but there are tools out there that will hold down a shim bucket and when the lobe is facing away from the shim it is possible to replace the shim so the timing etc is not altered.

[jim21070 2]

Not sure this can be done on the Peugeot, but there are tools out there that will hold down a shim bucket and when the lobe is facing away from the shim it is possible to replace the shim so the timing etc is not altered.

 

No, we're not that lucky The shim is underneath the inverted bucket.

[Mike Walker 0]

Shimming up the Cam is a pain in the arse, as the timing belt has to come off and the cam has to come out.

Checking them is easy though.

All you need is a set of feeler gauges.

 

So i'd guess 3-4 hours labour to get it re-shimmed?

 

Just to understand this a little more, what sizes are the shims and do you just stack them up. Is there only one correct way in terms of the overall size of shims to do this - if so why don't they just make one size of shim and how do people get it wrong oh and why didn't they just build in the correct spacing in the first place??

 

Forgive me if i'm getting completely the wrong end of the stick

[Super Josh 4]

what sizes are the shims and do you just stack them up.

 

No you don't stack them up, you measure up the gap and replace with a suitably sized shim that will put you back within tolerance. Sometimes you are lucky and can swap the shims around to sort out some of the lobes.

 

 

Is there only one correct way in terms of the overall size of shims to do this - if so why don't they just make one size of shim and how do people get it wrong oh and why didn't they just build in the correct spacing in the first place??

 

They did get the spacing right in the first place, but components wear and then the gap needs to be adjusted periodically. You can't just have one size of shim because manufacturing tolerances and component wear dictate otherwise.

 

 

Josh

[Mike Walker 0]

No you don't stack them up, you measure up the gap and replace with a suitably sized shim that will put you back within tolerance. Sometimes you are lucky and can swap the shims around to sort out some of the lobes.

They did get the spacing right in the first place, but components wear and then the gap needs to be adjusted periodically. You can't just have one size of shim because manufacturing tolerances and component wear dictate otherwise.

Josh

 

Erm, still don't get it So the shim is put under the cam?? Is this to raise the cam up a certain distance or something? Sorry really dont understand what the shims are for, oh and what wears?

[boombang 2]

You have your cam in the head. It has egg shaped lobes on it which rotate pushing down on "followers" or "lifters" or "buckets"

 

These then push onto the top of your valves to open and shut them.

 

The engine without shims would have a gap between lifter and cam - so you would lose lift and get a nice ticking noise (well a louder one than without anyhow!).

 

The head is put together without shims, the gap between cam lobe and lifter measured with a feeler gauge and the appropriate shim put in - obviously all the shims can differ purely down to machining tollerances and the lobes / lifters wearing differently

 

The shim then brings the lifter to nearly in contact with the lobe - there is still a small gap (which needs to be maintained) to allow for expansion of parts when the engine heats up.

 

Shim and engine too tightly (i.e. no gap left between lifter and lobe) then when the components heat up and expand the valves will not close properly - causing compression loss, loss of power, and inevitably valve seat burn.

 

First thing to do in your situation is to take the rocker cover off and measure the clearances with a feeler gauge

[Mike Walker 0]

You have your cam in the head. It has egg shaped lobes on it which rotate pushing down on "followers" or "lifters" or "buckets"

 

These then push onto the top of your valves to open and shut them.

 

The engine without shims would have a gap between lifter and cam - so you would lose lift and get a nice ticking noise (well a louder one than without anyhow!).

 

The head is put together without shims, the gap between cam lobe and lifter measured with a feeler gauge and the appropriate shim put in - obviously all the shims can differ purely down to machining tollerances and the lobes / lifters wearing differently

 

The shim then brings the lifter to nearly in contact with the lobe - there is still a small gap (which needs to be maintained) to allow for expansion of parts when the engine heats up.

 

Shim and engine too tightly (i.e. no gap left between lifter and lobe) then when the components heat up and expand the valves will not close properly - causing compression loss, loss of power, and inevitably valve seat burn.

 

First thing to do in your situation is to take the rocker cover off and measure the clearances with a feeler gauge

 

Fecking cool reply

 

So I guess the next question is what the clearance should be?

Edited July 28, 2006 by Mike Walker

[Super Josh 4]

Got to say Mike, your paintwork looks amazing. Great reflection and really 'wet look'. what have you used on her?

 

 

 

Josh

[Mike Walker 0]

Got to say Mike, your paintwork looks amazing. Great reflection and really 'wet look'. what have you used on her?

Josh

 

Five coats of paint and a coat of laquer

 

Cheers, I like it too.