Snapped Camshaft

Engine, Transmission and related drivetrain.
Button
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Snapped Camshaft

Postby Button » 25 Nov 2016 09:59

Hey guys, first off for everyone that celebrated I hope you had a Happy Thanksgiving.

So as you may have seen in a previous post, the L20 that I got with my project 510 ended up being junk so I had to get a new engine. After a little searching I bought an L20 with an A87 head for a great price from a guy that works on Datsuns and he said that the guy he got it from said it ran but if there was an issue to let him know and he will give me money back. So I pulled the valve cover yesterday and at first glance everything looked clean until I noticed the cam shaft had snapped in two and one of the cam towers had rotated. I'm not sure what caused this, maybe the engine overheated and warped the head which bound the camshaft? Lack of oil which caused a cam bearing to seize?

So my question is what kind of damage could this cause? Obviously I could try and return the engine to the seller, and I will do that if it's the best course of action, but it's a bit of a hassle to load it up and drive an hour and half away and then I am back to looking for an engine. The W58 head I had off my old engine looks good so I'm wondering if it's a bad idea to pull the head from the new engine and if the lower end checks out to just do a head swap?

From my understanding the A87 head is better than the W58 so Do you think that head is potentially salvageable and it's worth getting a new cam and have the head refreshed?

Any input would be greatly appreciated. I just want to get this car running and I keep running in to an issue around every corner.

Thanks.

Chris

In the first two photos below you can see the break in the cam and in the other three photos you can see how the cam tower is rotated in relationship to the head.
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defdes
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Re: Snapped Camshaft

Postby defdes » 25 Nov 2016 10:30

What do you mean by the cam tower "rotated"? It looks like all of the bolts are in. Valve damage is the most likely thing to check. It could have been improperly tightened towers (wrong sequence tightening) over tightening, not tight enough, warped head, improper line bore, cam tower swapped from another head etc.. You could pull the head, or just send it back.

510rob
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Re: Snapped Camshaft

Postby 510rob » 25 Nov 2016 10:37

Part 1 - you will resolve these problems, and then the cart will be super fun. don't lose heart over this.

Part 2 - someone did shit work on that head.
  • the long-side fastener holding the cam tower in place looks like someone over-tightened it, with the wrong sized socket.
  • the short-side fastener holding the cam tower in place looks like someone over-tightened it, stripped it, then did some patchy-dodgy fix; that fastener appears to be a stud with a nut on it, but the factory used hex head cap screws to hold the cam towers on.
  • the cam is broken because someone mangled the cam towers, not because of some mere coincidence or heat issue.

If that is the level of care and attention to detail given to that motor, I'd take it back to the guy, hassle or not.
a guy that works on Datsuns and he said that the guy he got it from said it ran but if there was an issue to let him know and he will give me money back.

take it back to him and get your money back, unless he wants to sell you the motor as a core for $50 - who knows what other monkey work you'll find in there...

Button
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Re: Snapped Camshaft

Postby Button » 25 Nov 2016 17:21

Thanks for the feedback guys. I' am trying to make sense of it still to figure out what they did wrong but the timing chain is not timed correctly and at top dead center the tab/driver for the distributor is at about a 1:40 position. Regardless I am going to pull the head to check the pistons and cylinders but will probably be returning this to the guy I bought it off of.

What do you mean by the cam tower "rotated"?
if you look at the third and fifth picture you can see that the cam tower has rotated a degree or two. the curved edge of the base of the tower should be aligned with same shape on the head if that makes sense. Also in the forth photo you can see that the head bolt is offset from curved bolt cutout on the cam tower.

the short-side fastener holding the cam tower in place looks like someone over-tightened it, stripped it, then did some patchy-dodgy fix; that fastener appears to be a stud with a nut on it, but the factory used hex head cap screws to hold the cam towers on.


Good catch Rob I didn't notice that on first inspection.

Button
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Re: Snapped Camshaft

Postby Button » 25 Nov 2016 21:08

So I pulled the head and the pistons ans cylinder walls seem good but there seems to be a Helicoil in the head bolt hole second from the front on the drivers side. This is the head bolt that went through the cam tower that seemed to be slightly twisted. There was also a lot of oil in this hole as you can see in the photo. That particular head bolt was covered in oil and it was also under the head gasket.

The front head bolt on the drivers side came covered in milky brown oil, seemingly oil and water got mixed here.

Any thoughts? Could incorrectly installing the helicoil twist the head bolt or cause it to be over/under torqued? Is it suspect to use that lower end with that helicoil?
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bertvorgon
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Re: Snapped Camshaft

Postby bertvorgon » 26 Nov 2016 09:31

That whole engine looks like there was a real hacker at work and no love was given to the assembly of that motor. It does give one pause as to what the bottom end would be like.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
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datzenmike
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Re: Snapped Camshaft

Postby datzenmike » 26 Nov 2016 19:00

The cam towers have alignment dowels the the bolts pass through. The bolts or in this case the stud only holds the tower on it doesn't align them. That stud should also have a washer under the bolt. The head bolt looks properly placed other than some photo lens aberration. I guess you could take the tower off and see if the alignment dowel is missing. The sensible thing would have been to install the cam and tighten it down then spin it to see if it binds. Something was missed here and/or the head is warped. Try a new cam and see if it spins freely.

The oil in the block bolt hole is just oil dripping down the bolt shaft. Usually it doesn't do this so maybe the cam tower was drilled out for the stud? Lucky the open valves didn't hit the pistons.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

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two_68_510s
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Re: Snapped Camshaft

Postby two_68_510s » 26 Nov 2016 20:51

As the crew at Monty Python said,"Run away, run away".
Joel

2 '68 510 2 door sedans
'95 240SX
74 Jensen Healey

“We will either find a way, or make one.” – Hannibal

Button
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Re: Snapped Camshaft

Postby Button » 27 Nov 2016 20:25

Thanks for the feedback guys, this is unfamiliar territory for me so the insight really helps. I have bolted the motor back up and the guy who sold it to me said he will refund my money.

Back to looking for another L20.
Last edited by Button on 28 Nov 2016 12:57, edited 1 time in total.

510rob
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Re: Snapped Camshaft

Postby 510rob » 28 Nov 2016 00:15

Best choice you could make.


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