Datsun Roadster Forum-311s.org

Okay so I adjusted the valves to 8 intake and 12 exhaust (hot) and after doing so my Datsun has developed an continuous tapping noise that gets louder and more frequent as engine rpms increase. I have adjusted the valves about 5 times trying to get rid of the tapping noise but have had no luck. Any suggestions?

I should also add that I can hear a rattling noise that I suspect is the timing chain, however the rattling noise doesn’t happen every time I run the engine and when the rattle does happen it only lasts a few seconds.

Try pulling each plug wire 1@a time reving and getting it to do it , If it goes away ....it ain't a valve noise.
Slow valves can do it ...ya have thin enough oil

In addition to what Don recommended, you may also want to have a careful read through pages 3 & 4 of the following thread. Your issues after ‘adjusting the valves’ are not uncommon …

viewtopic.php?t=26602&hilit=U20+valve+a ... t&start=30

You have one of your rockers going bad. They break the hard surface and get a low spot that makes that sound. No amount of readjusting will get rid of the noise.
Dave

david premo wrote: Mon Jul 25, 2022 11:26 pm You have one of your rockers going bad. They break the hard surface and get a low spot that makes that sound. No amount of readjusting will get rid of the noise.
Dave

Any tips on identifying a bad rocker arm?

You could try applying hand pressure to each rocker in turn, the offender(s) will go quiet hopefully

Rotate the engine and every time a lobe points straight up, lift the rocker on that lobe up and down, and back and forth. That’s about the best way to find it short for pulling them all out and inspecting them. Which is for sure the best thing to as many times other rockers are just starting to fail.
Dave

It may be that the arms are wearing. I'd be more concerned about pitting... check the cam and arm. You can adjust the exhaust tighter to 10 hot (8 cold)... that's where I run mine (6 and 8 cold). My engine (with a higher lift cam and other mods) makes more noise than some with a resurfaced cam and rockers... no big deal on my motor. The important thing to remember about valve adjustment is that the valve has to seat to transfer heat or it can "burn". Any extra room between the cam and rocker is to make sure this happens in all circumstances (mainly heat). Try going a little tighter (I like adjusting them cold myself), nothing to lose, just confirm you have space (6in, 8ex such that a 7 and 9 won't go and you have to wiggle the 6 and 8 a bit). If you decide the rocker (or cam) need resurfacing there are places that can do that properly (Delta Cam, Tacoma WA for example, so can Isky), and the vendors often have them in stock.

I just don’t understand how the tapping wasn’t present before I did the adjustment, I originally decided to do the adjustment because I thought my car was over heating but it turned out the gauge isn’t accurate, anyway I adjusted the valves without check the original spec and after I was done the valve train developed a tapping noise, which makes me think I could adjust it and eliminate the tapping noise? I should also mention one of the times I adjusted the valves I adjusted 6 intake 8 exhaust and the tapping went away but came back about two minutes after running the engine.