first half of my tune up results

[Zedyone_kenobi]

71 240Z with 69569 original miles on the engine.

Changed plugs, all were a lovely light brown color on the electrode but were burning cleanly and even. The last thread on each plug and the land that sees the cylinder was a a bit shiny black, meaning probably I have a tad bit of oil seepage down inside the wall. Car does not burn a drop of oil that is measurable, and never smokes.

Changed out the stock vacuum advance as the diaphram was completely shot. I am happy to report my car almost eagerly revs to 6500 before any drama. I think the carbs may need a tiny tweak or two, but my 5000 rpm wall is gone and she pulls smoothly up the rpm band. No hurry to mess with the carbs right now, but will eventually do a rebuild on both.

Checked the timing and I was pleased at the results. My only problem is I am not quite sure what the factory settings should be, but I am about to do a search.

At 800 rpm, I am running 7 degrees advanced. At 2850 rpm I am running 44 degrees. I do not know if that is too much or too little. But that darn vacuum advance is advancing!

Checked the engine vacuum at idle on the balance tube, and its sitting pretty rock solid on 17 in hg.

Next up are an oil change as soon as I modify my ramps to fit under my spoiler and I think I need to do a quick valve lash. I hear some tapping going on that sounds like a V8 rocker arm.

I have not run a compression check yet, but with the way the plug are burning and complete lack of burnt oil, I think it can wait. The car idles steady as a rock, the coolant is clear and clean with a lovely shade of green. I have no overheating issues to speak of and my oil pressure is good.

At idle when completely warm its 15 psi, and at 2500 rpm cruising when warm its about 45 psi. This is with 10w30, and since we routinely hit 100 degrees in Houston, I am going to bump it up to 10w40

So far the car responds very well to all inputs. And I am pleased. I am still leary of the clunk when in gear, I dont know if my rear end, or if its a u joint at the front of the driveshaft.

More fun to come!!!

[sblake01]

I've always run 10w30 in my cars and we regularly top 100 degrees here too.

[Zedyone_kenobi]

I just learned I should not have had my vacuum advance hooked up. Forgot about that, been so long since I had to set the timing.

Also, to those who are wondering, I am running the pertronix ignition in the distributor.

[Zedyone_kenobi]

Hopefully today my valve cover gasket will come in and I will be able to finish up the tune up.

Question though, are there any advantages to doing a hot lash, vs a cold lash. I know the tolerances change a tad, but I would think the hot lash would be a little better in as far as accuracy goes.

Just curious. Thanks. Also, what timing values on the low and high end should I be looking for w/o the Vacuum Advance hooked up ?

[sblake01]

I prefer to adjust the valves at operating temperature as per the FSM. I could give my timing figures but they'd differ from yours since I deal mainly with EFI and factory electronic ignition, but due to the Pertronix you have, I would think you could probably move you initial timing up a couple of degrees from the factory setting of 5 degrees BTDC to 8 or so (the EFI cars call for 7 to 10 depending on the year and as high as 20 degrees for the turbo models) but those more familiar with 240Z ignition could give a better answer.

[Zedyone_kenobi]

Well first I want to thank those who responded with such great advice.

I disconnected the vacuum advance and rechecked the timing. If you recall, with the vacuum advance connected I had

800 rpm 8 Degrees

2850 rpm 44 Degrees

Now with the vacuum advance disconnected I had the following

800 rpm 8 Degrees

3000 rpm 22 Degrees

So the vacuum advance was working overtime. Still I wanted to check out the inside of the dizzy to see what was going on with the weights down there to see if perhaps they had been tinkered with.

I got as far as removing the pertronix plate. I never found the centrifical advance mechanism. There was another plate in there that I could have removed but did not. I need to look at a schematic before I tinker too much with that. However, I did find a wire form the pertronix, a little black one that attaches to the plate the pertronix is mated to that was disconnected. I attached it, and cleaned everything up inside.

So really having done nothing but look at the pertronix hardware, nothing to it really, I put everything back together. I was leery of 44 degrees so loosened up the distributor and retarded the timing a tad. When I hooked up the timing light again to while the engine was running I had 5 Degrees advance at 750 rpm.

Throwing caution to the wind, I hooked up the vacuum advance again and low and behold I managed 36 Degrees at 3000 rpm.

Dumb luck, most likely. I have not driven it yet, but the way it starts and idles I am fine with. Very smooth and controlled. Next is the valve adjustment. Looking forward to that. Looks pretty easy actually according to that slideshow website floating around.

Opinions.

My next project after the timing is the rear end clunk. I am convinced that I have waaaay too much slop in my ring and pinion. I can rotate the drive shaft almost a half inch in each direction with the car in neutral. Not sure how to fix that other than tearing into the R180, may just try to find another one.

Anybody have a 1971ish R180 laying around for sale!

[Zedyone_kenobi]

update.

Valve adjustment has been complete on the engine and all valves needed a couple of thousands adjustment. Some were out several thousandths. The whole valve train is noticeable quieter. Cant speak of performance yet as I have not driven it yet. But thats coming as soon as this weather clears up.

Ordered my Diff from Zbarn.com. Very nice talking to the guys there.

After the diff is swapped out, I will turn my attention to some minor wiring fixes. I will also try to do a more thorough cleaning of the engine bay. Car is nearing mechanical happiness, so I am almost ready to spend many days cruising it around.

It just goes to show you that no matter how good of condition your 37 year old car is, its still a 37 year old car!

[xray]

I have had little luck from ZBarn regarding parts inquiries...many emails never returned. Guess I should just pick up the phone! So, were they able to verify that the diff you're buying doesn't have the backlash issues yours does? Or is it rebuilt?

Glad things are moving along. How's the ignition?

[jmortensen]

Well first I want to thank those who responded with such great advice.

I disconnected the vacuum advance and rechecked the timing. If you recall, with the vacuum advance connected I had

800 rpm 8 Degrees

2850 rpm 44 Degrees

Now with the vacuum advance disconnected I had the following

800 rpm 8 Degrees

3000 rpm 22 Degrees

So the vacuum advance was working overtime. Still I wanted to check out the inside of the dizzy to see what was going on with the weights down there to see if perhaps they had been tinkered with.

You have an unusually low amount of mechanical advance for an early Z distributor. I don't know the exact spec, but memory tells me they're supposed to have something like 22 or 24 degrees of mechanical advance. I would disassemble the distributor all the way down and make sure that it isn't all gunked up, clean and lube everything, and reset the timing. I'm not sure how much vacuum advance you should have, but your total mechanical advance is not enough in my opinion, especially if you drive in low vacuum situations a lot (if you're a leadfoot).

My next project after the timing is the rear end clunk. I am convinced that I have waaaay too much slop in my ring and pinion. I can rotate the drive shaft almost a half inch in each direction with the car in neutral. Not sure how to fix that other than tearing into the R180, may just try to find another one.

Anybody have a 1971ish R180 laying around for sale!

Checking backlash via the pinion is not the right way to do it. I would suspect that there is nothing at all wrong with your diff, as the slop is greatly magnified when you check at the pinion due to the cut of the pinion gear teeth. If you have a clunk check the normal issues: front diff mount, mustache bar bushings, driveshaft bolts, U-joints, splines on the stub axles. If you want to check backlash correctly you'll need to pull the diff and the rear cover, and check it at the ring gear.

[Zedyone_kenobi]

I totally agree with you on the timing. I pulled off the pertronix unit and hit a wall, where I got a little nervous as to how to continue. So I stopped. However with what you mention in mind, will pull her out and see how she looks all the way down to the distributor chassis. Need to find a how too guide to tearing down a distributor. Time to use the search button again.

As for the diff, I have checked the usual suspects. Front diff mount is good, mustache bar bushings appear in good shape, drive shaft bolts are tight, ujoints show no slop.

The stub axles are an issue. If I grab the axle on either side of the diff and push on it in the radial direction (normal to the central axis of the axle) It moves enough to feel and hear. I am pretty sure this is bad.

Also if go from 1st to reverse, no matter how slowly I let off the gas, it had a definite thud to it. Now once underway, the diff is quite as a mouse. It does not whine or make a fuss of any kind. I certainly hope that I do not replace this one with a diff that is worse than mine!

[jmortensen]

The stub axles are an issue. If I grab the axle on either side of the diff and push on it in the radial direction (normal to the central axis of the axle) It moves enough to feel and hear. I am pretty sure this is bad.

Actually that sounds perfectly normal. There should be lash in the gears. Running them without any lash will soon create a whole bunch of lash. Also, when you turn the halfshafts you're also involving the gears in the carrier, which would have nothing to do with a clunk that you'd hear when shifting. Backlash should be measured at the ring gear, not at the halfshafts and not at the pinion.

Also if go from 1st to reverse, no matter how slowly I let off the gas, it had a definite thud to it. Now once underway, the diff is quite as a mouse. It does not whine or make a fuss of any kind. I certainly hope that I do not replace this one with a diff that is worse than mine!

I wouldn't replace a quiet, extremely low mileage R180 with a junkyard R180. Think of it this way: what is the likelihood that the diff you bought has LESS miles on it than the one you're pulling out? Next to nil.

I personally have had zero luck trying to feel for a bad halfshaft U-joint with the shaft in the car. I have to take them out to have any chance of feeling a bad U-joint. If this is an early 71 with the diff moved forward relative to the later cars, that would make it even more likely to be a U-joint issue. U-joint problems were the reason that they moved the diff back in the later cars.

[Zedyone_kenobi]

I hate to admit it, but your words ring true. Actually I dont hate to admit it, but now it leaves me with more head scratching to do. I am going to keep the R180 I have on order coming and use it for comparison. I may even get it professionally rebuilt so I have a known good part. That is one job, I do not wish to tackle by myself.

Just note for clarification, I do not feel slop when I turn my halfshafts. I feel slop when I push on them radially, as in up toward the bottom of the car.