Fairlady rookie question

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Fairlady5150
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Fairlady rookie question

Post by Fairlady5150 » Sun Jul 07, 2019 2:04 pm

Decided to try my hand at classic car ownership, so I bought a sweet little 1968 1600. Engine is an early 1.6 L. I'm brand new to Fairlady's but learning a lot. The question I have for the group is regarding engine noise. Once I sorted out the leaking / noisy exhaust manifold, I was able to hear a tapping in the engine. Good news is it sounds like top end, not a rod. I really believed the issue was in the rocker shaft assembly, so I replaced it with a re-manufactured rocker assembly and adjusted the valves. Still tapping. So I'm wondering, does the Datsun 1.6 L just have a natural tick (like the old Dodge Slant Six)? If not, I'm open to suggestions / recommendations.

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pebbles
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Re: Fairlady rookie question

Post by pebbles » Sun Jul 07, 2019 8:08 pm

Yep things move around quite a bit when up to operating temps.
Check rocker geometry. If the head has been cut to the max, and/or a lifter/cam is worn, there might be one that is behind on the scorecard.
David




"When we were standing next to the motor while on the dyno, and the motor hit VVL, eyes went watery.."

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Re: Fairlady rookie question

Post by greydog » Sun Jul 07, 2019 10:13 pm

Is the tapping present both hot and cold engine? Does frequency or tone vary with rpm? Can you hear the tap at the exhaust
. Is it louder if you remove the oil fill cap?
Dan
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Fairlady5150
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Re: Fairlady rookie question

Post by Fairlady5150 » Mon Jul 08, 2019 6:10 am

Dan -
The tapping is present when cold or hot. Frequency tends to match rpm's I haven't tried removing the oil fill cap, will try that this evening and see if it's louder.

Thanks

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notoptoy
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Re: Fairlady rookie question

Post by notoptoy » Mon Jul 08, 2019 8:54 am

What have you set the valves to? I go a little tight, otherwise they do tend to sound like a singer sewing machine.
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Re: Fairlady rookie question

Post by greydog » Mon Jul 08, 2019 10:08 am

Just to eliminate possibilities, you might try removing the belt(s).
Is the emission equipment still on the car? Air pump and air injection manifold?
If it's been removed, how were the injection holes plugged?
I've found that when setting the valve clearances, I need to push down on the pushrod side of the rocker firmly for a few seconds...the pushrods seem to capture a bit of oil in the lifter pocket that will play hell with the clearance.
Dan
.68 SRL311 aka "Skortch". On the road again.
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spyder
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Re: Fairlady rookie question

Post by spyder » Mon Jul 08, 2019 11:05 am

I had a 520 pickup with a pushrod engine that had one valve that would tick at the specified clearance of .014 thousands. It would stop if I set it to .006?

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Mackn367
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Re: Fairlady rookie question

Post by Mackn367 » Mon Jul 08, 2019 12:26 pm

Sounds like it could be valve lash. This happened to mine too. I removed the valve cover and did the inspection (I also was new so i had to look up how to measure the valve lash by setting engine to TDC and proceeding from there checking each rocker. BUT let me be the one to say be careful! In doing this check I realized one of my studs was stripped so I had to remove the whole assembly and re-tap the hole... and now here we are with my car still on blocks (that was a year ago). It's a very slippery slope once you start opening things up.

I say either leave it or check them VERY CAREFULLY and be prepared for a few hiccups along the way. We are here to help :)

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Fairlady5150
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Re: Fairlady rookie question

Post by Fairlady5150 » Wed Jul 10, 2019 8:10 pm

by notoptoy » Mon Jul 08, 2019 8:54 am
What have you set the valves to? I go a little tight, otherwise they do tend to sound like a singer sewing machine.

notoptoy - The tech wiki called for 0.17 clearance for the rockers / valves, and my feeler gauges went from .016 to .018, so I set them at a very tight 0.018.

Fairlady5150
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Re: Fairlady rookie question

Post by Fairlady5150 » Wed Jul 10, 2019 8:13 pm

greydog - I recently replaced the belt, so it's new. It doesn't appear to have any smog equipment. I don't know a lot about the smog equipment, other than it was garbage, so I'm not sure what you mean about the plugging of the injection holes. Can I trouble you to elaborate on this?

Fairlady5150
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Re: Fairlady rookie question

Post by Fairlady5150 » Wed Jul 10, 2019 8:15 pm

by Mackn367 » Mon Jul 08, 2019 3:26 pm
Sounds like it could be valve lash. This happened to mine too. I removed the valve cover and did the inspection (I also was new so i had to look up how to measure the valve lash by setting engine to TDC and proceeding from there checking each rocker. BUT let me be the one to say be careful! In doing this check I realized one of my studs was stripped so I had to remove the whole assembly and re-tap the hole... and now here we are with my car still on blocks (that was a year ago). It's a very slippery slope once you start opening things up.

I say either leave it or check them VERY CAREFULLY and be prepared for a few hiccups along the way. We are here to help :)

Mackn367 - Which stud are you referring to? One of the two that hold the valve cover?

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pebbles
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Re: Fairlady rookie question

Post by pebbles » Wed Jul 10, 2019 11:14 pm

My guess is, a rocker shaft stud.
download/file.php?id=12538&mode=view
David




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Re: Fairlady rookie question

Post by S Allen » Thu Jul 11, 2019 7:35 am

This is the stud Mack is speaking of.
1600-head-stud.jpg


This does definitely cause problems. Good to check both to make sure they are secure.

Steve
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Re: Fairlady rookie question

Post by greydog » Thu Jul 11, 2019 10:06 am

The idea behind the belt removal was to eliminate possible noise sources (if the water pump and alternator aren't turning they can't make any noise.
There is quite a bit of info regarding the emissions system available by searching but, in short, an air pump pushed air thru fittings in the head. Those fittings (one for each cylinder) fed the air into the cylinder at times. When the system is removed, it used to be common to plug the injector passages with pipe plugs. The turbulence in the cylinders made a sort of ticking or chirping noise.
Probably the easiest things to do are-
Loosen the fan belt to see if the noise changes
Readjust the valve lash a bit tighter. check the rocker stand studs to make sure they're solid and not stripped.
If neither of those steps has an effect, we'll need to look for more guesses.
Dan
.68 SRL311 aka "Skortch". On the road again.
'69 SPL311 aka "Scooter" terrorizing the streets
1990 Nissan 300ZX
2008 VW GTI
2017 VW Passat

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Gregs672000
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Re: Fairlady rookie question

Post by Gregs672000 » Thu Jul 11, 2019 10:32 am

Why is the valve lash so wide on R engines? I realize it's a push rod, but why do they need so much lash (expert please explain!)? It's always been my understanding that the lash was there to allow the valve to seat so as to exchange heat with the head. I've heard of racers running as close to zero lash as they could in order to get the most lift out of the cam. The U20 manual calls for 8 intake and 10 exhaust hot (10 and 12 cold, which is the exact opposite of what it should be, as testing has shown the valve lash loosens with heat). I run 6 and 8-9 hot for a few reasons, but as long as the valve can seat it should be fine, and I would think that would apply to the R as well?
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