U20 Valve Adjustment Specs?

[bengelhardt]

I just adjusted the valves on my 1970 2000 and when I started it up the valvetrain made a fair amount of noise. So, I pulled the valve cover back off and double checked the clearances - everything checked out fine.

THEN I went to the trusty 311s.org site and discovered that the specs quoted there ( http://www.311s.org/tech/engine/adjustvalves.html ) had the specs for intake vs. exhaust inverted when compared to the Clymer Manual that I used in the first place.

The Clymer manual says that the exhaust valves should be set at .008" and the intake valves should be set at .012" (both hot of course.) The 311s.org site says that the exhausts should be set at .012" and the intakes should be set at .008". Which one is right?

I have a feeling that the 311s site is correct but I just want to be sure.

Also, are there specs for setting the valves cold? I've got the valve cover off right now and I'd really like to set the darn things before I put it back on for the umteenth time.

Thanks in advance for any help that you folks can lend.

[spl310]

The factory manual shows that the intake should be at .008 and the exhaust at .012 hot. It does not show a cold setting. I have seen a spec for it cold, but don't recall it off hand.

[Minh]

I would lean towards trusting the factory manual...

BTW: Chilton's has it at .008 for both (hot)

[bengelhardt]

Some friendly roadster owner on the Datsun Roadster Email List brought to my attention the fact that the metric dimensions are not properly converted to SAE on page 20 of the manual (which is the page that I was referring to.) They show .3mm converting to .008" for exhaust and .2mm converting to .012" for intake. They also pointed out that on General Information page (3), the values are correctly converted.

So, just for the record:
Intake = .008"
Exhaust = .012"

Now I need to go fix it.

Thanks for the help.

[Mike Unger]

Bill: For cold settings use 0.002" less. Intakes 0.006", exhaust 0.010"

[Minh]

Bill: For cold settings use 0.002" less. Intakes 0.006", exhaust 0.010"

Are you sure on this? I would be very happy to believe it is true...

[bengelhardt]

Thanks for the tip Mike.

Minh - I did a little testing and Mike's suggestion that cold settings are .002 smaller seems to hold true. I checked clearances that were set to .008 & .012 hot and they were, in fact, .002 smaller after the engine cooled off.

[Tonymig]

What type of wrench is best used for larger bottom nut when adjusting the valves. Seems like all the wrenches I have will fit it but really can not make a full insertion of wrench due to things being in the way.

[Mike Unger]

What type of wrench is best used for larger bottom nut when adjusting the valves. Seems like all the wrenches I have will fit it but really can not make a full insertion of wrench due to things being in the way.

There are wrenches available called "tappet wrenches or thinline wrenches". If you get a pair of these, one for the locking bottom nut and one for the top adjuster it makes things easier. Alternately, you can buy a couple of dedicated wrenches and grind them down to fit easier and stick them in your toolbox for future use.