Timing chain inspection

[Peter Cripps]

This is a follow-on from my distributor questions, but I thought I'd start a new thread.

In the picture below, I rotated the engine to TDC, with the cam marks lining up. Actually, the first thing I noticed was that they didn't line up, at least not exactly. The intake cam seemed to be a few degrees behind the exhaust cam. Then I tried moving the chain up and down ... ummm, seems like it moves a lot:




Pushing the chain down advanced the intake cam slightly, and as shown the cam marks now line up pretty well. This suggests to me that the chain is indeed worn; I can't see any other way for the cams to be out of relative alignment. Or maybe I'm expecting too much accuracy in cam timing?

Thanks as always,

Peter

[m!]

What is the situation regarding the interval to change cam belts?

For the 1300 & 1600

Where can I get a decent one - I've seen them for sale on ebay but really wouldn't want to trust something so important. Does anyone have any idea on he best make of cambelt? I'm looking for 1600 but a note on all would be helpful.

Thanks

m!

[lucas Geheniau]

You should turn the engine in the right direction, then the marks should be correct.
Even with a worn chain, the relative position of the cams should be correct(if they have ever been), because there is only a very short piece of chain between the cams.
Another story is the timing , between the cams and the crankshaft you have a long piece of chain so that wear can have more influence on that.

Looking at the lock plates on the cams, I don't have much confidence in the mechanic that has worked on them..........

Kind regards

Lucas

[Peter Cripps]

Thanks Lucas. Yes, I had the same thought about the long section of chain between the crank and the exhaust cam. It seems that the mark on that cam wheel lines up pretty well.

Am I right in thinking that there is a fine adjustment on the camwheels? The manual seems to imply that there is ... it talks about removing a dowel. My engine is a 303 if that makes any difference.

Sorry about all these beginner questions ...

Peter

[Huib]

The S1 and early S2 Fulvia's had a vernier adjustment.

If the timing mark is on the camshaft itself at the back of the sprocket wheel you have one with the vernier.

If the timing mark is on the front of the sprocket wheel you do not have the vernier. Some prefer the vernier. They say it allows very fine adjustment. In practice I was always spot on with the non vernier camshafts. Apparently Lancia did its homework well.

If you have the vernier (there is also a thick washer under the head of the bolt to hold the pin) you have to use the 2,2 mm method. The mark is not accurate enough. It is there more for the purpose of preventing you from bending any valves when putting an assembled head on the the block. Let me know if you have it and I will explain the procedure for getting it very very accurate.

If you have the non vernier, use the marks but I always check with the 2,2 mm method. Better safe than sorry with these things.

Some months ago I rebuilt again an S3 engine after having done a dozen S1 engines. Took me the better part of an hour to find the timing mark as I had completely forgotten it as the the front. Reminds me of my first trip to the USA in 1973. I had to go to silicon valley but the decided to go a few days early and visit an aunt in Altadena (Los Angeles). I called her from Hollywood Burbank airport. She told me to wait and she would pick me up in an hour. I answered not to worry, I would rent a car. Less than an hour later I was in the right street but it took me hours and hours to find the right house as the housenumbers where on the side of the sidewalk!

[Peter Cripps]

Thanks Huib. I can see the timing marks from the front, so no vernier adjust, I guess.

I did read through the procedure to check timing that's given in the manual ... seemed to involve measuring valve clearances at TDC? The way I've done this on other cars is to attach a degree wheel to the crank and find the points of peak lift on exhaust and intake cams. So, yes, please could you describe your 2,2 method!

Regarding numbers on the sidewalk, I had many similar 'cultural disconnect' experiences when I first moved to the the USA. Now I have the same problem when I visit friends and relatives in the UK. Not recognizing coins and banknotes is a particularly embarrassing example!

Peter

[Huib]

Either by design or by mathematical derivation from the cam profile / timing or just by measuring it, Lancia established that the lift of both inlet and exhaust valves should be 2,2 mm at TDC. This is on page 01/0400 of the technical data book.

You turn that around. Set the valve clearance of IN and EX on #1 at 2,2 mm. Turn the engine forward (CW). The tappet screw should touch the valve at TDC. In practice I use a 0,10 feeler gauge to check when the screw hits the valve so I set the clearance to 2,3.

To check the exhaust timing you turn the engine backward (CCW). I write it this way to paint a picture. It is all right to turn the engine backward but because of the backlash any measurement is not accurate. So you turn the engine forward and ruin your feeler gauge by having it between the screw and the valve stem of a fully opened valve. When you can pull your feeler out again the engine should be at TDC. I cheat and turn the engine backwards a bit past the mark to eliminate backlash and then forward.

[Peter Cripps]

Ah, now I understand, thanks. I'll be able to check this over the weekend and report back. Maybe the timing is right and the marks slightly off!

Peter

[P. de R. Leclercq]

The timing marks are not exactly accurate: they are only a guide, especially on late S2 and S3 cars with the one-pin one-hole system. The vernier system is vastly superior in my view - it also permits a little "meesing about" which can be entertaining at least.

When retiming an engine, I always have the engine just a couple of degrees advanced , so when I check the timing (full engine rotation at 2.2mm) the timing is usually exactly spot-on at 0° (TDC).

[Peter Cripps]

Results from timing check:

Exhaust: lift @ TDC = 1.9 mm
Intake: lift @ TDC = 1.8 mm

I made these measurements using a dial gauge on the #1 valve spring caps, setting it to zero when the valve was closed, then winding the engine forward to TDC on the #4 firing stroke.

Actual lifts might be a bit higher, since the dial gauge stem was not exactly parallel to the valve axis in either case.

As previously mentioned, the exhaust cam mark lines up pretty well at TDC, but the intake mark is slightly behind. I needed to rotate the engine about 3 degrees in order to line it up; this is an estimate based on the distance between the 0 deg and 8 deg marks on the flywheel.

Vernier cams would be nice.

But, bearing in mind that all these parts are at least 35 years old, I think that's pretty reasonable. I'm still a bit surprised at the amount of slack in the chain at TDC, but since no-one has commented I'm going to assume it's OK.

Thanks to all for your help. It was an interesting exercise, at least for me!

Now on to shimming that distributor ...

Peter