Dadsun

I've now listed mine on Hemmings Auctions. Be gentle. https://www.hemmings.com/auction/1973-datsun-240z-bains-la-602827

That white 1973 Z is a beauty. That's what I have, a white/red 73 that I've put refurbished paltech round top carbs in. I'm planning to sell it soon. Too much kids college tuition stacking up. Bought from the original owner 4 years ago.

So, the head seat on that intake valve has dropped and the head needs to be rebuilt. Not my specialty. Any suggestions on where to find another head? Just trying to compare the two options.

I just finished doing this comparison. The stuck valve when compared to fully closed valves is a little low, but not much. Nowhere near as low as ones fully pressed by the cam lobes. So, it looks stuck, but I guess there's a chance it's not bent or damaged the piston. I'm trying to avoid pulling the head because that's out of my expertise, which means getting it towed to a mechanic. Unless I can unstick it. Open to suggestions. I searched old threads and some people try penetrants and/or disassembling the valve.

I should clarify that I can move that rocker arm into place over the valve guide (lash) and push it down to seat it in place, but it springs back up. So, that tells me the valve is stuck?

Locknut isn't loose. I get what you're saying about the base circle wear. I've never adjusted the valve lash, so I'll research it. But in any case the valve appears to be stuck down (open). How would adjusting the lash help that?

I think I found the source of the noise. See pic. One of the rocker arms is not seated in the valve rocker guide (term from the repair manual, also pictured).

Two more pics of the timing chain center pulley, which looks off.

It was a single pinging/knocking that sped up when revving, and it occasionally was a louder knock like something was loose, so I immediately shut it down. This all happened while under the garage at cold startup. I've taken off the valve cover and don't know where to start to diagnose. Here are pics. Any help on what is the most likely culprit and path to diagnose is much appreciated. Thanks.

My exhaust header is ceramic coated.

Yes, same, it came with the flat top original configuration I inherited from the original owner. I tried to clean it up, but then realized I was probably given myself cancer and had no chance to actually get that gunk off. It didn't line up with the roundtop carbs anyway. I bought the fuel rails in my OP pics from someone on this forum. Back to topic, I should really get more scientific and measure the fuel rail temps at different times. But, not even sure it's a problem now that I fixed some fuel and fuel filter issues (again). I need to reproduce it.

My question is the same as @AK260's... when you say you went all rubber, did you contrive a return to the hard vent line as well?

Anyone come up with a halfway elegant solution to separate the fuel rail from getting the transfer of heat from where it's bolted into the engine block? (5 places) I have a 1973 240z that has the Paltech refurbished SU carbs (not the stock flat tops) and when I take it on a 5 or 10 minute drive the fuel rail is hot to touch. Not burn my fingers hot but definitely uncomfortable. Am curious if anyone has built aluminum "stilts" or used the same kind of material that is used as a heat block between the carbs and intake manifold. (See where my finger points in the pic)

So, I'm thinking about posting my car online at BAT. It's a 1973 white/red 240z that I bought 3 years ago from the original owner. 47 years owned! I even have the original sales receipt and title. Summary of things I've done or in a couple of limited cases (suspension), paid to have done: Gas tank restore, chem wash, all new vapor and gas lines, fuel filters, etc Restored original steel rims and 1973 set of hubcaps; added more classic profile tires Installed rebuilt SU ('70-'72) Paltech carbs, powder coated air housing, new coolant lines, fuel rail, yanked out 73 emissions bits, etc Suspension: Eibach progressive springs, shocks, bushings, Motorsport Auto sway bars 1973 bumper molding replacement (bump/fender gap) -- this was extremely hard to find; wound up buying it from another Z Forum user from Denmark Exhaust system: New ceramic coated header and full performance exhaust system (Motorsport Auto) Reinstalled original 6.5w radio + 2 5" speakers + tied-in to replaced retractable antenna Installed separate bluetooth, amp, 2 6x9 speakers for upgraded sound experience Interior (new): vinyl kit, door panel restoration, new upholstered seats (Motorsport Auto), replaced red interior panels throughout, floor mats, rearview mirror, new ashtray, center console, etc Full detailing of interior, insulation of interior for noise reduction, fixed tachometer wiring, fixed break system leak, speedometer cable replacement, choke cable refurbishment, misc grommets and fasteners, electronic ignition, new ballast Original 4-speed manual transmission. Original color was Himalayan White, but it is currently a Pearl White. Motor was rebuilt about 20 years ago. Compression good across all 6 cylinders. Still have tons of original parts including the flat top carbs and air filter housing Working A/C. A few pics below. Any thoughts on best sites? I'm guessing BAT, but also considering eBay or Hagerty Marketplace.

How'd you determine it was running lean?

High end flutter? Hmmm. I seem to have that too. I haven't checked the floats yet as someone mentioned at the start of the thread. And the flutter/sputter only happens when accelerating fairly aggressively in the 2800-3500 rpm range, it seems. That rpm range while sitting still and just steady revving doesn't produce the flutter. Any ideas? I've got fresh gas. Right now it's a mix of 91 and 87 octane, all ethanol free.

It is stock engine and good compression; was rebuilt about 15-20 years ago by original owner. I will try the 87 for a few weeks and see how it goes.

Thanks for the info on the float level. I will take a look. And also will have to refresh my memory on the mixture nuts turns. I'm pretty sure I wound up settling exactly halfway between all in and all out. I had bought and used the mixture tester that uses color.of the flame via spark plug port, but that seemed to work only once. Since then it shows a yellow flame no matter what I do. Back to the subject topic briefly: I have access near my house to both non ethanol 91 and 87 octane. Should I go with 87?

Since then I've swapped in the fuel rails to go with the round tops. I run 91 octane because it's the only ethanol free gas around here.

Here's a pic from the last time I was adjusting them. Notice that I'm running coolant through the intake manifold. Some choose not to do this, right?

Yeah, apologies for the sparse info. Here's a thread on my conversion to the Paltech refurbished carbs. This was to replace the original flat tops which were sorely neglected and of course problematic.

My Z seems to be running rich. I have swapped in the SU rebuilt carb set and adjusted as best I know how with the unisyn tool and mixer adjustment on the bottom.

Well, that's depressing.

Btw, Test 1 worked. It slowly moved the needle to almost full.

So, after I posted I went and switched the wires at the sending unit. Now it's showing closer to accurate. The gauge needle came up off the bottom of the gauge when I turned on the car and settles the needle right at E, which is about right. I've since added 3-4 gallons and the needle only moved up a little, like less than an 1/8 tank. So, I'll fill it up and see what it shows, but I think I'm back to how it was last year, showing less than is actually in the tank. How do I adjust that? Tinker with the sending unit?