Hi, my Z has been off the road for several years and I was able to get it started but it would stumble horribly, backfire, and die so I decided to go through the basics and now I've been able to make so much progress that it will not start at all. These are the things I did before it would barely run.

Drained tank and filled with new gas, new fuel pump, new fuel filter, new fuel soft lines, very basic disassembly and cleaning of carbs, replaced needles and seats, adjusted bowl floats with help from Z-therapy, new spark plugs and adjusted the carburetor nuts down 1.5 turns.

I did read a post, from someone here I believe, that most problems we thought were carburetor were actually not so I set about trying to check/adjust the timing. This is what I did:

Found what I believed to be TDC by turning the harmonic balancer nut with a wrench until #1 piston was at the highest point on its compression stroke. I did this by inserting a rod in the spark plug hole and watching for it to be pushed out by the cylinder as far as it goes. The timing pointer did line up with deepest mark on the pully and the distributor rotor pointed at the #1 plug wire. I decided to replace the points and here is where it gets iffy ... I thought I had dropped a washer down inside the distributor and so I completely removed it but it turns out that I didn't. While it was out, I cleaned it a little and then reinstalled it and set the points to 0.50 mm. While the distributor was out I did spin the distributor shaft and may have reinstalled it where the slot that mates with the shaft tang was 180 degrees off from where it was when it was removed. I don't know the internals of the distributor so, would that have made a difference as long as I reinstalled the button correctly so that it pointed at the #1 plug wire? Also, I don't believe it is a fuel issue because I used to be able to squirt a little gas directly into the carbs and it would fire up and run a few seconds off of that. I've attached pictures of how things look when I believe I am at TDC. While it was out I did notice some play between the part of the distributor where the points sit and the shaft tang mates but it seem to be under spring(?) tension because when you release it from a twist it snaps back to its original position. The other thing is that I don't think the shaft tang was at the 11:25 position but more like 12:00. (The shaft tang picture is not mine but from another post.) If that is the case, does that point to what I should do next? Thank you for taking the time to read all of this and I would appreciate any tips on next steps or correcting something I missed or made a mistake on so far.

When you set tdc, did you make sure you were on the compression stroke? First two cam lobes pointing up. You can check this through the oil filler hole

30 minutes ago, Tomcat said:

now I've been able to make so much progress that it will not start at all.

Let's see if we can a start a fire and burn it down.

31 minutes ago, Tomcat said:

I cleaned it a little and then reinstalled it and set the points to 0.50 mm.

Have you confirmed that you still have spark? The other half of the coil circuit is the ground side. The points are grounded through the distributor body. Maybe you knocked a wire loose or broke that ground circuit.

If you get the rotor in the right place you can twist it to open and close the points, to see if you have spark. You'll see a spark between the points and one from the coil each time they open, with the key on.

I think spark and/or timing might be the issue. Recheck that you installed the distributor correctly and that all spark plug wires are in the correct position. When changing mine I accidently had them all installed one position clockwise. The car wouldn’t start and backfired like crazy.

Also verify that you have spark and the timing is set correctly. Spark can be check by removing the plug and just holding it against the head but timing should really be checked with a timing gun.

I did verify the compression stroke with my thumb plugging the #1 sparkplug's hole that I read about on here. I was silly of me not to check the spark but didn't because it at least tried to run before. Now I don't think I'm getting any spark out of the coil so that's where I'm headed next. I'll double-check that the plug wires are correct and check the timing once I'm getting a spark. Does the 3rd picture indicate that the static timing is currently set 10 degrees BTDC if I truly am on the compression stroke and the timing pointer lines up like the second picture. Just to make sure, is there's any chance that the distributor's internal shaft being 180 degrees out of where it was when I removed it could be a problem ... It just rotates the cam, correct?

I appreciate all of your help!

Edited April 13Apr 13 by Tomcat

I've been surprised at how vaguely Nissan described the ignition timing marks and how to use them. It's confusing. Like the R and the A on the base of the distributor is not described anywhere that I've seen. And the wording in the FSM is difficult to be sure of. "Inspector's side"? If the inspector is on the "side" the marks run up and down not left and right. Probably means from the front. Translation problem.

I think that you're probably correct on everything except that I would set the distributor at the center mark between R and A to begin. Pretty sure that R stands for Retard and A for Advance. So, the center should be zero, or the desired starting point to Retard and Advance from. I don't think that you want to start at R though.

Set in the center. Once running use a light.

I typically set the distributor based on where the rotor points. I want it just on the advanced side of the terminal at TDC. The R-A plate is not a good reference because it is adjustable too with the bolt underneath. I have also had situations where I couldn't get enough advance with both bolts shifted all one direction

On 4/13/2026 at 7:08 PM, Zed Head said:

... Pretty sure that R stands for Retard

Nissan may have thought it acceptable to use that terminology in the 1970's but today? I'm sure we can find more appropriate and less hurtful language...

How about Revance? Revance and Advance.

https://www.etymonline.com/word/re-

https://www.etymonline.com/word/ad-

Throwing it out there......You said you replaced the fuel pump. I have heard that some of the aftermarket pump arms are too short and dont make good contact with the eccentric (hope its ok to use that word).

Sorry to be away so long. I've been working on an old Chevy truck and just now getting back to the Z. I think I did or verified almost everything you guys have suggested. I went ahead and bought all new ignition parts ... coil, dist. cap, rotor, points, capacitor, plug wires, etc. because they were either old or original, not very expensive, and I felt it was the path of least resistance. So I start on the fuel side. I have fresh gas, a new fuel filter, and verified I'm pushing fuel through the fuel lines. So next I think my carbs are OK ... they're original and ran well before it was off the road for some time and did a very basic cleaning. I did find this article very helpful because it is so basic and straightforward that I, a entry-level mechanic at best (certainly for the Z) https://zcarguide.com/tuning-adjusting-datsun-240z-su-carburetors/ was able to follow it step-by-step. So I set about trying to set the float level and I'm blowing through the fuel inlet and adjusting the float to the shut off at 9/16 drill bit level but they are both hard to blow through and one is a lot harder than the other so I think there is a clog somewhere. I check the float bowl needle valve and they seem OK and I'm suspicious about the part that connects the fuel line to the float needle valve and start looking and poking around ... not really sure what the inside path looks like so I decide to open it up. I had tried once before and the bolts were so tight that I thought I might damage the whole assembly so I never looked inside. So I decided "what the heck" ... it's suspicious and something I've never checked so I soaked it in penetrating oil and cranked on it ... all the time waiting for something to break and this is what I found. After I scraped off as much as I could I wasn't even sure what I was looking at when I found the two aluminum (?) rings and what looked a piece of tape or a thin piece of beef jerky. I didn't even know that there were filters in there and I'm really amazed that the car would start at all. I've cleaned all the parts and ordered new filters and when the get here I will go through all the steps starting again at ground zero. I'll post back after that but I'm thinking that was the main issue all along. I know it's a long post but I thought that someone else out there might run across similar symptoms and not know about these little filters ... or maybe I'm the only one?