[Roadsters] u20 cam timing

[robert k. smith]

hi jon, if the intermediate shaft, big gear is  a tooth off, it will

throw the cam gear 1/2 a tooth off. i ran into this quite afew years ago.
good luck, bob smith, ohio
> From: tom at datsun2000.com
> To: datsun-roadsters at autox.team.net; shas1983 at netzero.net
> Date: Sat, 19 Jun 2010 17:21:16 -0700
> Subject: Re: [Roadsters] u20 cam timing
>
> Jon,
>
> I had an upper chain stretch and jump a tooth in my '70 2000 sometime
around
> 1972. Back then I had no idea what the death rattle meant. I think at that
> time it cost me about $30 for a couple of new valves, gaskets, and timing
> chains. I can't remember if I changed any of the gears, but I remember
> correctly I did change the upper tensioner because the Datsun mechanic
> recommended it.
>
> If your not pulling RPM's I think I would look somewhere else. There have
> been a few discussions about carburetion, or ignition systems that could be
> doing this to you.
>
> Tom
> 69 2000 - Mr. Hyde
> Portland
> http://www.datsun2000.com
> http://www.nowroc.org
>
>
> On 6/18/2010 9:25:01 AM, shas1983 at netzero.net wrote:
> Does anyone have any experience with a u20 cam timing being off 1 tooth or
> less? I have aligned the cam with TDC and counted chain links per the
> original
> service manual. The engine cranks easily and runs pretty well at lower
> rpms(under 3000), but seems to loose power and not readily want to climb to
> higher rpms under load at speed (free revs easily). The odd thing is I had
> to
> advance the distributor timing well past the std 16% to get the engine to
> run
> well.
>
> When I turn the engine over and stop it on #1 TDC per the crank the lobes
of
> the cam on #1 appear to be silghtly advanced past 10 and 2 and the intake
> vale
> on #4 appears slighlty compressed more than #4 exhaust. It looks like they
> are
> advanced at most less than 1 full tooth (15% on 24 tooth sprocket), so I am
> wondering if the combination of a resurfaced head and cam tower shims could
> have changed the chain length enough to account for this?
>
> I have an adjustable cam sprocket that I can try (+- 6 degrees), but I was
> wondering if others have seen this before I change the sprocket. I would
> have
> expected the engine to run far worse than it does, but I have just about
> ruled
> everything else out. Seems good at lower rpms but just does not pull past
> 3000
> rpms like it used to.
>
> Jon Carlisle
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