Issue when trying to adjust valves

[ramsesosirus]

Hey guys

Sorry if this sounds stupid, but I've never adjusted valves before.

I read all the appropriate info and got the right tools (feeler gauge, crows feet wrench socket, 27mm socket, torque wrench) and know how to do it but...

When got the No. 1 cylinder lined up, so the cam lobe points up, I can't get the nuts loose. I think the top one is the locking nut, botttom is adjuster. The locking nut is reg thread, righty tighty lefty loosey?? I could NOT get the top one to budge.

EDIT: Okay I feel stupid now, I rechecked the write up and it appears that the BOTTOM nut is the lock nut, so I would need to lossen THAT first with the crows foot... right??

I used the 14mm on top, 17 mm on bottom. It almost feels like the 14 mm is SLIGHTLY too big for the top nut, is this the right size for it? I was trying as hard as I could to loosen it, but if I pulled any harder it felt like it would strip (since the 14mm seemed a little big). I decided not to break stuff as the car does run half decent. I tried two different 14mm wrenches to make sure it wasn't just the wrench, both seemed slightly too big.

As far as the adjustment, I only checked No 1 Exhaust (FAR left from passenger side) and the No. 2 intake (these two have the cam lobe pointing up at the same time).

So cold adjustment, Exhaust 0.25 mm, Intake 0.20 mm; I could get the 0.30 mm feeler in the exhaust with a slight drag, but no bigger. The 0.25 also had a little drag, bu

Would this small of an adjustment affect the way the engine runs much??

The main prob I have right now is a low rpm backfire. I don't know if its intake or exhaust backfire.

Thanks guys, lookin forward to getting the Z out, I still haven't actually drove her yet, cant wait!!

This was also the first time I've turned an engine over by hand (socket/ratchet on crank, w/o plugs installed) and it really helps you understand how the valve system works!

BTW In case anyone has any other advice, the things I need to fix are: The low RPM backfire, rear brakes leak (I think from the "T" above the tank, how do I get to that?), and the infamous clunk, which I will investigate further when I get the car out, and also the ignition key is kind of loose and the door handles/locks need work. I will also check fuel pressure when I get a gauge for it; if the pressure is not high enough, and I put a new FPRegulator on, does that indicate the pump?

Edited February 17, 2009 by 280ZSS

[racebird1]

Unless the valves are tapping and making a lot of noise that may not be your problem. The backfire may be in the intake but the most common causes range from intake air leak such as throttle body boot. That causes the engine to not know the exact amount of air it's actually getting or it can be from improper timing. Try checking the timing and look for leaks at the intake air. I believe only 1/2 of the valves can be adjusted from that spot then you may need to rotate 1 turn to do the rest. I could be wrong it's been 28 years since I did a adjustment. The rocker is usually a little loose on the ones you should be adjusting at that spot. Not the ones that are tight. Good Luck

[ramsesosirus]

The only reason I am stuck on adjusting them is since I don't know when they were last adjusted, and they sound like a "sewing machine" when the car is running, is that an indicator, or is that normal?

thanks for the reply;

I should add it ONLY backfires at low RPM, like just after you take off from a stop. Once you are going 30-40 mph, its much smoother, no backfire.

Edited February 17, 2009 by 280ZSS

[Phred]

I havn't got much time here, but I have a pic of the adjuster. The top 14 mm nut is the adjuster, the 17mm is the lock nut. Don't try to turn the 14mm adjuster without first loosening the jam nut. The 17mm nut is sometimes pretty tight, but the adjuster is rarely tight. Point the lobe up, and set intake at .008, and the exh. at .010 cold. good luck.

Phred

[racebird1]

My 76 which I am restoring and dont have on the road yet has the same backfire when giving it some gas from a idle. I have not adjusted the timing yet but I know it gets better or worse when playing with the timing. The valves on mine are very quiet.

[Walter Moore]

As Phred mentioned, the 17mm nut on the bottom is the lock nut. I have seen those so tight that I couldn't move them. Sometimes it is easier to loosen all the lock nuts when the engine is cold, then snug them just a little, start the engine back up and get the engine warm for the final adjustment. (They really need to be adjusted hot.)

Edit: remember to re-install the valve cover before starting the car...

I have had to use a flare-nut wrench and a hammer to loosen those nuts before. It took me about three or four tries to get my valves adjusted correctly the first time. Remember that setting them a little loose (too much gap) is safer than setting them tight. (Less performance perhaps, but also less likely to burn an exhaust valve.

And remember when you finally have the valve lash adjusted to not over tighten those lock nuts.

Good luck Mr. Phleps...

Edited February 17, 2009 by Walter Moore
Forgot a detail