NC280z

So I'm getting mixed opinions on air/bubbles in the pre-pump filter. Does anyone else have a clear filter before their fuel pump, and if so, do you have any bubbling? I've always thought that any bubbling in the line was indicative of air in the system, and needed to be resolved.

That's correct, 200213's the VIN, and thanks for the quick reply! I've got a glass fuel filter inline between the tank outlet and pump inlet (low pressure) and noticed a good amount of bubbles in the filter while the car is running. Filling the tank a bit higher reduces the bubbling significantly, which I assume is due to a pinholed pickup tube pulling in air. I was concerned that the diameter difference between the pump and tank might cause cavitation or other issues.

Greetings everyone! I've discovered (rather embarrassingly) that the fuel tank in my '75 280z (production date 12/74, 213th produced based on VIN) actually belongs to a 260z! I found this out after troubleshooting a fuel issue related to a rusted pickup tube that's been introducing air into the fuel line. There are NO 75-76 tanks in usable condition available anywhere that I can see and reconditioning this tank is likely not an option, so my question is this: can I replace my tank with a new, baffled 260z tank? I know that the primary difference from 260z tanks to 280z tanks are baffling and pickup tube diameter (5/16 vs 7/16). The fuel pump I'm using is a NOS unit (7/16 inlet), and the car seemed to run fine until the pickup tube pinholes became large enough to suck in air. S30World is working on a new production tank for 75-76's, but those won't be available until late this year and the new 260z tank I've sourced is available now and could be in-hand in two weeks. The engine in my Z is a warmed-over N42/N42 flattop with stock F/I system, so I don't think it'll need crazy amounts of fuel. I suppose my main concern is any issues that could come about from a 5/16 outlet on the tank going to a 7/16 inlet on the fuel pump.

Looks like filing it by hand was the solution, don't know why I didn't think of it before. I'm honestly just surprised that the hub had been damaged, I have no clue what could've caused it.

I thought it might be a wheel/tire, but I've swapped wheels and only the driver's side has the shake. I've got the car on stands and when you spin the wheel it's pretty visible that the wheel isn't evenly mounted to the hub on the driver's side, due to the ridge. I'll go snag a photo and post it shortly.

Good evening all! I've finally located the cause of a mild, persistent wheel shake. It would appear that the driver's side front wheel hub has a slight ridge near the rim between two of the studs, which is preventing the wheel from mounting flush. The ridge isn't significant and should be easy enough to flatten, but I'm looking for some guidance before I take a drift to it. What's the best way to flatten out the ridge? OEM hubs are NLA, so I'd be looking at T3 replacements if I can't fix the stocker.

Fortunately they sent a return label without any difficulties, I'm just waiting on it to arrive at the retailer for a full refund. Based on the box the head came in, it would seem that Go-Powertrain is a storefront for Allied Motor Parts from GA, and AMP does not have very good reviews. Oh well, on to the next project.

Hi all, I was doing a bit of work on my '75 280z and noticed something odd on my passenger side strut tower. The seam closest to the front of the car for the passenger side strut tower has a few spot welds that are curled up, the rest of the strut tower spot welds/seam is nice and flat. I've owned the car for 7 years, and I don't recall the previous owner mentioning any sort of accident history. Is this indicative of damage from an accident, or just something resulting from age or factory oversight? Nothing around the area is wrinkled, or suggests any sort of major accident.

The pits on the deck were my biggest concern, that and one of the valve guides is so corroded that it looks like the upper portion of the guide is missing. Overall, it looks like they shaved the head, painted it and shipped it out. I don't know how you get so many metal shavings in the box it was shipped in, it's as though they took it off the mill and just chucked it into a box and sent it out. Not too happy, I've sent a polite request to return the item, so we'll see how it goes. As always, I appreciate your input (and sanity check!) datzenmike. I'm glad I wasn't over-thinking this one.

Good evening all, I recently purchased a rebuild N42 cylinder head from "Go-Powertrain" to prep for a larger cam and use on another build and noticed some things with this remanned unit. Cylinders number 5 and 6 have a bit of pitting, both in the chambers and on the deck of the head. I haven't measured the head yet, but I'm guessing it's been shaved a bit, as there's metal flakes all over the head, and some of the flakes are trapped under the valves along with bits of shop rags and other debris. Would these pits present much of an issue? I know that pitting is usually a sign of casting defects or of detonation damage, and that these pits can fill with carbon deposits and create hotspots that worsen preignition. I tend to be overthink things, and I don't know what to make of the pits on the cylinder head deck that are close to #5's combustion chamber. Run it or send it back?

Good afternoon everyone, I'm restoring my '75 280z to the original radio system and need some help figuring out the polarity for the single (mono) speaker that these cars came with. The original speaker is missing, but the stock white and white/black wires are still there. The FSM and factory diagram available from XenonS30 and other sites do not show which color wire is which polarity, and the replacement Hitachi speakers I've acquired from a Datsun 1200 have the striped wire going to the negative side of the speaker. Does anyone here still have their original speaker setup, and if so, which wire goes to which terminal? Thanks in advance for any help you all can provide, I've searched just about every forum and have come up empty-handed. The majority of the posts on other forums only show how to determine a speaker's polarity, not the polarity of the wiring from the head unit.

So it's been a few weeks and I'm happy to report that the oil leak has been resolved. I just figured I'd do a follow-up in case someone else runs into a similar issue, I'd recommend following the Chilton/Haynes manual's advice of coating the side-seals with RTV rather than with engine oil as recommended in the "How to rebuild" book.

That helped, thanks! I ended up purchasing a 260z expansion tank, as it's made of metal (early 240z are plastic) and it had all the requisite vent inlets. It's very odd that the stock '75 setup didn't have all the correct inlets, I'm not certain what the stock setup would have done to ensure proper tank venting with all the extra outlets.

Good evening everyone, I'm doing a refresh of the fuel system to my '75 280z (changed the topic of the original post to suit), and I've got a quick question regarding the vent lines on the expansion tank and the outlets on the fuel tank. It looks like the '75 model year was an oddball for differences between the fuel tank and expansion tank, as the fuel tank has 3 vent tubes but the expansion tank only has connections for 2 vents, plus the line that runs up front to the evap canister and a line to the fuel-filler neck. The main difference is that the '75 and older fuel tanks have a 1/2" vent tube right near the exhaust that was removed (probably for obvious reasons) in later model years and it does not have a mate of similar inlet diameter on the expansion tank. If I keep the topmost vent lines ran to the expansion tank, would it be alright to just cap off the 1/2" vent tube? What would you all recommend to cap the tube? The previous owner had a mishmash of adapters and tubes to run the 1/2" vent tube to the expansion tank, but left the 3/8" vent tube open to atmosphere which I believe has led to moisture in my fuel and a rapid degradation of the fuel itself. Tank photo borrowed from another Z site, as below:

I appreciate the quick responses! I tend to drift towards the worst-case scenario when I notice things like this. I had a machine shop bore and hone the engine, and I reassembled/refreshed the engine with new internals about 7 years ago and never noticed the damage during the reassembly process. During today's inspection I also noticed deposits on all of the pistons (see below), but all of them have this same even coating of deposits, which I'm guessing is normal for an engine like this. My idle AFRs are between 12.5~13.5, so a bit rich. N42/N42 with flattops, so compression is around 9.69~1 and it's happiest when on the rich side.