pistons and valves contact

[rgh0]

Yes Rohan the cams turned smoothly, the dowels are stil there in the cams. The teeth on the inlet sprocket looked a bit worn so I replaced it, The sprocket is marked for either EX or IN according to how you fit it, I am sure that I am fitting it correctly because it lines up with the dowel.
I will try the old sprocket

Cheers John

I am not sure i understand by what you mean by the statement below
"The sprocket is marked for either EX or IN according to how you fit it"

The sprockets normally have only one dowel hole which is positioned differently on the Exhaust versus the Inlet. Is one sprocket marked Ex and one IN as they are not interchangeable?
Where did you source the new sprocket from ?

Without photos this is hard to diagnose but doing wonders for my post count

cheers
Rohan

cheers
Rohan

[checkrail]

If you imagine a clockface , at six o'clock is the middle hole which fits the dowel, ,at 12 o'clock printed on the rim of the sprocket is EX and printed immediately to the left of that is IN. So the two marks are at adjacent teeth, not on the point but in the dip at the bottom of the teeth.
The sprocket came from QED, so a reliable source

Cheers John

[Hawksfield]

Rohan
The replacement sprockets are common to both cams. You use the corresponding mark for the cam you fit it too. So checkrail will use the IN mark in place of what would have been a dash mark on the original.

John

[Phil.C60]

You can use a plunger type device or a wooden dowel to find TDC as long as you are fairly near it. If you leave the wooden dowel in the spark plug hole and try and turn the engine over completely I think that when you turn the engine over it can hang down low enough that when the (inlet?) valve opens fully it catches the side of the dowel as the head of the valve overlaps the spark plug hole. Just a thought.

[rgh0]

OK if the timing is correct assuming the new cam sprocket is installed and marked correctly and the correct old sprocket has been used also, then the last thing I can think of is that a valve is sticking open. I would recheck all the valve clearances looking for one valve sticking part open. If thats the case then its head off again to fix the valve. If thats not the case then i suggest you get someone who knows these engines to come and have a look at whats going on

cheers
Rohan

[steveh]

As you are struggling mechanically to interpret what is touching and where , i would be placing plasticine or engineers blue on top of the offending tdc pistons ie 2+3, that will tell you whats happening or not .
Another scenario could be that a protruding piston is hitting the head gasket.
Really though as others have said you would be best with a knowledgeable Twincam person helping .

[checkrail]

At last! I have managed two complete revolutions with a spanner on the crank with the timing marks virtually level. The only thing is the timing chain tension does alter slightly as you go round.
I removed the wooden dowel as suggested by Phil in Worthing, I wonder?

John

[Phil.C60]

Well, John, you seem to be getting somewhere at last!
I did pm you, do call me if you wish.
Regards Phil

[checkrail]

Yes, thank you Phil very much obliged. I hope tomorrow to get the rotor arm back to its TDC position. I have an electronic dizzy so took a photo for reference before I started disturbing anything.

Regards John.

[Spyder fan]

Are we there yet ?

[Spyder fan]

Sorry for the previous post if it offends anyone, but I have been having a lot of fun following this saga in that I have been there and done that, and that and that as well as that in my quest for making my Elan/s …..

It’s great to see the community coming together to help out and provide a solution.

Thanks everyone

[rgh0]

At last! I have managed two complete revolutions with a spanner on the crank with the timing marks virtually level. The only thing is the timing chain tension does alter slightly as you go round.
I removed the wooden dowel as suggested by Phil in Worthing, I wonder?

John

So did you replace the new sprocket with the old sprocket and was that what fixed the issue or was it something else you changed ? If it was the wooden dowel jamming and going solid in the pulg hole surely you would have seen that as you turned the engine?

Timing chain tension fluctuates as you turn the engine by hand as the valve loads change around on the cams

[Hawksfield]

Checkrail

Glad to see you are happy with the cam timing now, have you fired it up yet?

Let us know how it goes

John

[checkrail]

Disaster! Finally got it fired up , gently running at 1000/1500 rpm for no more than 5 minutes then a metallic noise.
I switched off and on again, but it would'nt start. The starter motor sounded as if no load on it
Result; Timing chain snapped
Exhaust cam bent at the sprocket end
Broken and cracked on the head where the cam slots in
Shut the bonnet and taking my Greyhound for a walk

John

[AshleyPark]

That's bad luck! It's a shame you were never willing to post any pictures of your engine, I dare say someone would've been able to diagnose your problems had you done so.