David, it is important that you determine where the sound is coming from. A
chain will rattle more than tick. Does it tick fairly consistently? If so,
that
would suggest valve train noise, like a loose valve. Was the head rebuilt? Has
the head been retorqued since it was rebuilt? Has it gotten hot? If the sound
does not go away with adjustments to the valves, I would have some concerns that
the head might have dropped a valve seat. Before you run the engine again, go
get some feeler gauges and check the valves. It is fairly easy: At this point,
don't worry about getting the engine to operating temp, let's just check them
cold. Take the valve cover off so you can see the cam. Look for the lobes on
the cam that are sticking pretty much straight up. Look at the lobe and
determine if it would correspond to an intake or an exhaust valve. Take your
feeler gauge and slide a 10mm gauge between the lobe and the rocker arm (for an
intake) or a 12mm gauge for an exhaust. If it slides in really easy with no
resistance, then go up few mm and see what how that one fits, and so on until
you can't fit the gauge in anymore. If the 10mm (or 12mm) won't fit to begin
with, then go smaller until you get a gauge that will. If they are radically
different, then adjusting them will probably take care of the problem. If you
don't know how, we can help you through it, or someone local will (I just want
to
diagnose the problem first). If those valves are OK, then turn the engine over
by hand or by bumping the starter and look for the next two that are more or
less
straight up (keep track so you know that you eventually check them all). It is
easier to turn or bump the engine if the spark plugs are out!!! If the valve
are
not majorly out, then I would have concerns about a dropped seat (I've seen it
happen. Nissan used brass valve seats which heat at a different rate than the
aluminum head, and unless they were staked in properly (or replaced with steel
ones), they can drop out, especially if the engine has over heated at some
point. You MIGHT be able to look inside the engine through the spark plug hole
and see the seat sitting on the valve, but you would have to turn the engine
over
slowly and really be able to look in. The only other way (without pulling the
head) would be to pull the intake and exhaust manifolds and look directly inside
the valve ports while turning the engine over by hand. I give all this warning
about checking things like valve adjustment with the engine cold first because,
if the seat has in fact dropped, the more you run the engine the more likely the
seat is going to go cockeyed and damage the head, valve, cylinder and piston.
At
this point it might just be loose but not completely dropped, so it makes a
ticking noise when the valve spring closes the valve back tight against it. Let
me know if I can help. Unfortunately, I live in Washington State, otherwise I
would come by. Good luck!
Greg Burrows
Mtbdavid2@aol.com wrote:
> Hi all,
> I just finished rewiring a good part of my wiring harness and now my engine
> is making noise. I have a 68 solex 2000. I purchased the car at the end of
> last summer. The motor was rebuilt in 2000 and doesn't have many miles since
> the rebuild. Just today the motor started making a ticking noise which is
> fairly loud and I am not sure if it's the valves, the timing chain or
> something else. I was wondering if someone locally in the SF bay area, CA
> could drop by and lend a hand. I need to adjust the valves and check the
> tension on the timing chain. Is there supposed to be slack in the timing
> chain and if so, how much? I need assistance in adjusting the valves as I
> have never done this before. If someone locally could lend a hand I would
> sure appreciate it. I want to the have the car in good running condition for
> Solvang. Thanks in advance.
> David
> 510-552-0529
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