Arne

Clogged fuel vent or flow guide valve? Try running it with the gas cap off or loose?

Done. #99. Almost to 100!

British SUs, as built by Skinner's Union, as opposed to Hitachi SUs built under license. My MG had brass damper caps.

Oops! You're right. My bad. Worn, incorrect, bad or improperly adjusted needles, I'd guess. Float levels too high might affect that too.

Hmm, I haven't got there yet. In fact I actually find "working on 30+ year old cars and....sourcing parts for them" to be almost as much fun as driving them. Recreational and takes my mind off work. In fact, that was the problem with the MGB - restoring it and hunting down the correct parts was much more fun than driving the finished product. Not so the Z, so I can't yet foresee the day I'll want to sell mine.But those days do come for many of us. They're only cars, and when they fail to be entertaining, it's time to move on.

The one I was trying was not broken that way, I had seen that page before and checked. But that's another point to look for (in addition to worn shaft bushings) when looking at a used ZX dizzy. I agree that there are several potential advantages to a ZX dizzy over the smaller 240Z unit w/Pertronix. But my uses are mild and my L24 is stock, so the Pertronix choice was simple and works great for me.I recall that beandip had instructions on making a simple travel limiter for the ZX advance mechanism. that may be something to look into also.

After looking at the pictures in this thread closely, I'm now pretty certain that my downpipe is original down to the outlet end of the cast/stamped Y. From the outlet of the Y back is custom. All the pictures here show the pipe going to the rear a ways before turning in to follow the tunnel back. Mine turns to the center almost immediately after exiting the Y. So since it has already been buggered by the original owner, I feel OK with whacking that part off (after the Y) and doing it better than now. Still don't know if the Y is cast or stamped, but leaning towards stamped. I'll try to get under the car this weekend to check.

I also use NGK wires and they seem just fine. Other good brands for L-series are Taylor and Magnecore. But the NGKs are fine and far more affordable.

Done. Pin #98.

Then 205/60-14 should fit fine, and probably 215/60-14s as well. With the wider size my concern would be on the front while turning, at the front valance corner. But if those awfully tall 205/70-14s don't rub there now, the 215/60-14s shouldn't rub either. More tire selection in 205/60-14 though.

Well, at this point I'm going to work on the assumption that mine is (at least mostly) original. (I'll explain the 'mostly' part next.) But considering how many early cars we see here with the other style, the thought that Nissan may have had two suppliers is looking fairly good. As an example, while many of us know just how rusty Jim's car (a7dz) was, and that it seems likely that the exhaust could have been replaced due to rust at some point in the distant past, on the other hand, he doesn't remember it, and that unique 'Z' or 'N' badge on it gives pause. So either type might really be correct. We may never know the details for certain. To Geezer - I don't know if it is cast or stamped. Kats' site refers to it as cast, but that may be an artifact of translation. I've always assumed mine is stamped in two halves and welded. I'll need to get under the car and check closely to determine which method was used. As for my 'mostly' original comment - all this has me reconsidering just what I have under there. The original owner had the exhaust re-worked early in the car's life. He apparently didn't like the way the stock exhaust sounded. The exhaust is all welded into one piece, downpipe to glasspack in the tunnel to a long tailpipe out the back, all of it 1 3/4" pipe, as I recall. I've always assumed that the muffler shop cut the old off just behind the cast/stamped junction and welded new on from there. Looking at Kats' pictures, now I'm not so sure. Now I wonder if the entire stock downpipe was retained and the glasspack was welded to the end where it would normally mate with the center resonator. If I can determine that to be the case, I may want to retain as much of the downpipe as I can, by removing the glasspack and building from there back, rather than building from the junction back as I thought had been done last time. I guess I'll need to find time to crawl under the car this weekend....

No knowledge of the Nexxens. As for size, do you have any idea how much the car is lowered? Do you have an air dam, or stock valance? And when you say you have "Iron cross" wheels, are they the 14x6 280ZX wheel, or the earlier 280Z 14x5.5 wheel, which is different but some people also refer to as an "Iron cross"?

OK, so Jim's car has the same type as Mike's new system, and Jim knows the history of that car from new, so we can assume that it is original to the car. The other used one that Mike has appears to be an original, but we probably can't confirm that. I'm fairly comfortable in saying that mine is original too, considering the low miles, lack of under car rust, and all the rest. Mine also matches 26th's. Conclusion? I'm thinking now that Nissan got downpipes from more than one supplier. It might be totally hit and miss as to which style a particular car (or batch of cars) got.

Stephen, I now think that would be a good idea. Problem is that none of the many guides to installing a ZX dizzy on an L24 make mention of the delay valve. I'd never heard of the device until long after I gave up on the ZX ignition, for pretty much the same reason that Steve describes. I suspect that the lack of knowledge that they exist is the main reason no one uses them. Steve, as I mentioned above, I gave up on my ZX dizzy. I believe that mine was from an '83 automatic, but had the earlier E12-80 module. But I had to use 93 octane fuel and drop back to 5° BTDC or less to keep it from pinging under moderate load at highway speeds. I went back to the stock 240Z dizzy with a Pertronix, and am back to 12° BTDC now with no detonation, and will experiment with a bit more advance or maybe lower octane fuel shortly. I didn't do any measurement of the total advance on the ZX dizzy, but came to that same conclusion just from my testing.Of course, not everyone has an original 240Z dizzy that's not worn out like I did, so my alternative may not work for a lot of people. But I do agree that the vaunted ZX ignition is not a totally trouble-free option in all cases. Adding the delay valve that Stephen mentions is probably a good option, if they can be easily sourced. Or re-curving the ZX dizzy is another good choice, if people can find a good place to get that done. But considering the advancing age of even the newest of the ZX dizzies, and the number of those that by now also have worn shaft bushings, I'm wondering if the simpler option might soon be to buy a remanufactured 240Z dizzy off the shelf and stick a Pertronix in like I did. A bit more expensive than a ZX dizzy from the pick-n-pull, but perhaps a better choice in the end. I can't remember Steve, are those carbs still original? Not remanufactured? In theory, the whole approach of the SU design is to keep the ratio fairly steady through-out the rev range. If the idle mixture is way richer than under load, one thing I'd suspect is a vacuum leak at the throttle shafts. With a vacuum leak, one of two situations occurs: you can tune them either rich at idle/good at speed; or good at idle/lean at speed. If my carbs were worn, I'd want to have mine set like yours rather than lean at speed.So it might be worth checking the throttle shafts for vacuum leaks.

My thoughts are similar. It sounds like the rear carb isn't working to me. As mentioned, check the rear carb piston to make certain it moves freely. You mention the float height at the front carb, what about the rear? Has that been checked?

Thanks, Dan. That is the type on my car, built in 7/71. So are we trying to decide that all the ones pictured in this thread (Mike and Jim's) are later replacements, not original to the car? Or that mine was replaced with an earlier type later in life?Direct link to the pictures on Kats' webpage.

No, it's not the overall height of the tire that's the problem - it's a visual thing. Almost an optical illusion. The shorter the sidewall (lower profile), the bigger the fender gap looks, even if it is really unchanged and the tire diameter is the same.

Bear in mind that both Dave and Jeff's cars are lowered. The 16" tires don't look nearly as good (IMO) on a non-lowered car. That's part of the question as well.

Hmm. The image on the parts CD is pretty much what mine looks like. It lists the same downpipe through 8/71, and a different number for 9/71 - 6/72. I've seen other so-called 8/71 parts on my 7/71 car, so I wonder if my downpipe is actually a '72-style?

Thanks, Mike. Useful info, but opens a whole new question. I'm looking at the construction method of both the new one you put on #137 and to old one above, and they aren't the same as mine, which I would have thought was original. In both of the ones you pictured, it looks like the forward manifold outlet is one long pipe all the way back to the center muffler joint, and the other manifold outlet is cut and welded into the first to create the Y. Mine on the other hand, both manifold outlets feed into similar length tubes, which are both welded into a Y adapter, and the single tube to the center muffler is welded into that. Dang hard to get pictures with the car on the ground in the garage, but hopefully this shows what I'm talking about. Was the new downpipe you pictured only used on really early cars? I can't believe that mine has been replaced, but it's not similar in construction to the ones you have/had.

I don't disagree with much so far in this post, except to say that there's no need to rule out 14" and 15" if you're not looking for tires with state-of-the-art handling. Sure, if you want modern grippy tires, you'll want to go 16" or larger. But for a pleasant weekend drive, don't discount normal 14" or 15" rubber.The fact of the matter is that the very tame 195/70-14 all-season tires on my car right now probably have as much or more grip than the very best street-performance tires that you could buy back when these cars were new. No, they're nowhere nearly as good as the Hankooks that Jeff is running, but for my driving style, and -- as important -- the way I want my car to look, they are just fine. We need to bear a couple of things in mind regarding performance tires. One is that the rims that fit early Zs well aren't very wide by today's standards. It's very common for us Z owners to pinch 225 width tires on 7" wide wheels. That's not a problem, but those tires would work much better on 8" or even wider wheels. But we can't really do that, so we're not going to get the most out of these modern tires. Nor is the S30 suspension all that well suited for modern rubber. It does OK, but there is a lot more camber change on these cars than is best for todays tires. So here's my advice -- decide what is important to you in wheels and tires. Appearance? Ride? Handling/grip? Because the answer to this question will determine what type and (to certain extent) sizes you should be looking at. For my car, I wanted period-correct vintage looks and fit. I really like the tall sidewall look of the stock height 14" tires/wheels. That's not for everyone, might not even be for me forever, or if I get a second Z...

Mike, that's what the insides of all three of my cars' tanks looked like, and I left them all be as is. Sold both of the parts car tanks, and am using the red car's tank with no issue. As long as the feed tube in the tank is clear, I'd let it ride.

Realistically? No. If you weren't able to drive and test it while it was still in the donor car, there's not much that you can tell now. You're probably just going to have to install it and cross your fingers at this point. Not certain. You would not need to cut if your car was a 4 speed swapping to a 5 speed, but there may be a spot-welded plate covering part of the hole on your automatic car. If so, I should think you could get it out with hand tools though.

Neither. In today's terminology it would be a 175/80-14.

Gladly. Consider it done.