Are my chains to short or ??

[Lyndon302]

911 sixty seven S
New chains. Guides. One idler. I used the stompski tool to set the cam timing. I had a feeling it wasn't right I had to back off the bolt all the way and it was still tight.
Now I'm fitting my cam tensioners there is not enough slack to get it in.
It came apart fine. I even checked the new chains against the old and they were within a mm.
Clearly im missing something or have it in the wrong way.
HELP
Lyndon

[Richey]

I think everything looks ok . You do not need the tensioner safety collars . I can't see in your picture how much more the tensioner needs to be depressed .

[Lyndon302]

Ok fitted. As long as the chains don't wear if I have a failure the tensioner body will grab it.
Lyndon

[stownsen914]

At some point you can pull the covers after your chains worn in and probably stretched, and install the collars at that time.

[cmcfaul]

That does not look right. That chain has no give and is going to break. Are you sure you got the right chain and chain tensioner? Are you sure the chain is on the teeth in the case?

Chris
73 911 E

[Flat6pac]

Did you replace the sprocket on the idler with a sprocket with more teeth?
Bruce

[Lyndon302]

I replaced one idler. As far as I know it was he same. Same tensioner type. 930 that came out of it. Both sides are the same so the idler wheel must be correct. I've turned it over 100 times doing the timing etc. Runs smooth. ???? Its buttoned up now. ��

[Daugaard]

How much base gasket do you have under your cylinders?
have you in any way changed the distance between the crankshaft and the camshaft?

[Lyndon302]

Yes.. .25 mm was in and I added 1mm for a total of 1.25mm.
Lyndon

[Lyndon302]

I have fitted some Ecurie engineering Wisecos and needed the 1.25 mm to get my deck height

[stownsen914]

They make sprockets with fewer teeth to handle special situations, in case you need to go that route. I know Dawes Motorsports in PA, USA sells them. Probably others do too.

[Lyndon302]

I believe it has a minimum of 4mm travel left. Going on 3.3 for a collar install this will be fine.. It will only go the right way when it gets hot or wears.
Lyndon

[RSstop]

Lyndon, Are those chain boxes from an early aluminum case motor? I have seen this before on the early motors.
I blamed it on new intermediate shaft sprockets that were perhaps slightly larger for the same tooth count.
Or another explanation, the later plastic chain guides are slightly taller than the original alum/hard rubber.
The early sandcast chain boxes seem to have a slightly different geometry.

[Lyndon302]

Yes. Early engine Sixty seven. All aluminium.
Lyndon

[Richey]

I'm sorry to say but after looking at your last picture I think the chains are too tight . You should definitely remove a cover and look at things when you drive the car and the engine is warm . The engine expands and the chains get tighter when the engine is hot .

[faapgar]

Adding 1mm to the bottom of the cylinder is not good.You should machine the outer edge of the piston top to get your deck set or a little relief in the heads.You have made the motor wider and that changes the chain angle.You have reduced your CR as well.Take it apart and do it correctly.Ciao

[cmcfaul]

I would not run it that way. Chain breaks and all kinds of badness happens. That chain it too tight.

Chris

[Lyndon302]

Do you think. 1mm extra on the base shim causes this. It would shorten the chain 2mm.
Lyndon