Timing Chain Broken..

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scotcochran
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Timing Chain Broken..

Post by scotcochran »

Hello, yesterday went to start my 1967.5 roadster and after a backfire out the tailpipe it quit running. Turned it over some more and it didn’t start. Checked and there is no spark and there is no valve movement. Assuming it is a timing chain?.

Can I fix this in the car? The engine is newly rebuilt by me. What should be replaced if it is the chain.

Your expert advice is appreciated.
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nismou20
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Re: Timing Chain Broken..

Post by nismou20 »

Did you pull the valve cover and inspect? Chains are pretty tough. Does distributor turn? How do you tell if valves didn’t move? You’ll need to present more info here. 1600?
scotcochran
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Re: Timing Chain Broken..

Post by scotcochran »

Yes, pulled the valve cover and removed distributor cap. Neither valves or the rotor moved.
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Daryl Smith
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Re: Timing Chain Broken..

Post by Daryl Smith »

1600? Assuming.....since a broken chain should be obvious on a 2000....
One other thing comes to mind:
Broken camshaft?

Going on the assumption that the other things I can think of would likely make a noticeable noise when turning the engine over....

I would start the diagnosis by pulling the timing cover.... which means the fan and fan shroud first....crank pulley....etc... :)
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scotcochran
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Re: Timing Chain Broken..

Post by scotcochran »

Yes, its a 1600. It is peculiar that there is really no weird sounds when turning it over.
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Re: Timing Chain Broken..

Post by JT68 »

You can possibly fix it in the car-probably much easier on an engine stand.
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theunz
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Re: Timing Chain Broken..

Post by theunz »

I know that the U20 is an interference engine, is the 1600 as well? If it is then you might have bent some valves after the chain broke.
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Re: Timing Chain Broken..

Post by JT68 »

Both engines are interference. Highly likely there are a few bent valves. Head needs inspection.
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spl310
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Re: Timing Chain Broken..

Post by spl310 »

You may be able to find a running 1600 for cheap. You could swap engines and keep the car driving while you rebuild the original. I know a guy with two engines sitting in his garage - two were runners iirc.
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scotcochran
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Re: Timing Chain Broken..

Post by scotcochran »

Update: well its not a chain, the camshaft broke. The end twisted right off. Anyone know how this could happen? Bearings are good and I can spin the cam easily. Also, anyone know where I can get a new stock canshaft?
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Re: Timing Chain Broken..

Post by DAC21 »

scotcochran wrote: Mon Feb 22, 2021 12:28 am Update: well its not a chain, the camshaft broke. The end twisted right off. Anyone know how this could happen? Bearings are good and I can spin the cam easily. Also, anyone know where I can get a new stock canshaft?
Rallye (datsun Roadster parts.com) has them as well as Datsun Parts .Com Of course you will have to pay the core charge as yours would appear to be FUBAR.
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Re: Timing Chain Broken..

Post by C.Costine »

Just wondering what may help someone else from your misfortune. Were the cam bearings replaced?
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Re: Timing Chain Broken..

Post by JT68 »

scotcochran wrote: Mon Feb 22, 2021 12:28 am Update: well its not a chain, the camshaft broke. The end twisted right off. Anyone know how this could happen? Bearings are good and I can spin the cam easily. Also, anyone know where I can get a new stock camshaft?
Hi Scot,

If the bearings are nice, it was probably just a stress fracture. It happens, but its rare. We have plenty of R16 cams on hand. What engine SN? We probably have both SAE and Metric as well as all the required timing components.

Cam bearing fit is important though, if too tight it will seize/gall - too loose, the cam will oscillate(not a good thing)- so that should be checked.

j
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scotcochran
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Re: Timing Chain Broken..

Post by scotcochran »

Thanks all for the input. Yes, the engine components were all new, including bearings. I put a bolt in the end of the cam and turn it and it feels good. No lateral movement at all that I can tell and rotates nicely. The engine always made a rattling sound when running. Sounded like loose lifters. I'm wondering if they were related.
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Re: Timing Chain Broken..

Post by Datsunparts.comInc »

What does the front of the camshaft retaining plate look like? What does the back of the large sprocket look like where it touches the retaining plate? When you installed the camshaft and sprocket did you rotate the assembly and check the end play prior to installing the lifters and chain. How did that feel?
Where did you get the timing sprockets?
Pictures?

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