DaveN

Aftermarket springs often mess up the ride height -- several examples in recent posts here and in zcar.com. "Stock" Nissan replacements will probably still be the 72-73 OEM version. They were wound a little longer than original 70-71 springs to allow for the weight of aftermarket A/C installations, and superceded them in parts stocks. The longer springs make 70-73 Z's ride about 1/2 inch nose up with no A/C, which doesn't look quite right. The slight rake of an A/C equipped 70-71 looked good, it just reduced ground clearance a bit more than Nissan liked. The rate is probably still OK -- Z springs don't have a history of losing their temper -- so if yours aren't rust damaged you may be better off keeping them.

Guessing you still have the stock ignition system.... it's probably a simple ignition problem, just an indication the car is due for a tune up. Try new plugs (one heat range colder if the old ones have deposits melted onto the insulators) & make sure the dwell is right. If that doesn't fix it the next suspects are the distributor cap (arcing from one contact to it's neighbor) and the plug wires (insulation breakdown).

From the 6/74 USA/Canada parts book: 14004-E4600 70-72 240 -N3300 73 240 -N3601 260 E30 and E36 aren't listed.

Re sticky linkage -- Steel on nylon ball & socket joints will stick and slip when dry. The best lube I've found is a homeade paste of graphite powder (lock lube) in silicone grease. A graphite coating on the nylon cures the stickiness. The grease is mostly a binder. Silicone grease catches less dirt than petroleum based greases. The same paste or moly assembly lube also work well in the metal to metal joints & bushings. Re aggressive linkage geometry -- 73 and later linkages have a slower opening geometry. I've heard 73-74 bell cranks can be used on 70-72 cars (with some adjustment of push rod length), but haven't tried it or seen an example.

1st checks: 1. (a long shot, but easy) If the top of the battery is dirty clean it. Underhood dirt can be conductive enough to slowly drain a battery. 2. Disconnect one battery cable (with the battery charged) and use a DC ammeter to measure current between cable and the battery terminal with everything in the car turned off. Should be ca. 100 milliamps or less. If the leakage current is OK everything other than the battery is OK, so it must have an internal (high resistance) short. That's not unusual in old batteries or after a few deep discharge cycles. If the leakage current is high you'll have to trace it through the wiring or just disconnect things 'til it goes away.

Keith, It's normal for SU's to need several seconds of cranking on cold starts, especially after sitting several days. If they're in good condition and adjusted correctly it ain't gonna fire on the first turn. You need EFI or a downdraft carb with an accelleration pump for that. With no accelleration pump there's no way for SU's to prime the manifold before the engine turns over, you have to have to do that by cranking it at full choke. A week between starts is long enough for some of the most volatile ingredients in the gas to evaporate from the float bowls, so makes it take a bit longer to get a flammable mixture to the cylinders. If it's really hard to start you may not be getting full mixture enrichment in both carbs. With the "choke" lever all the way back the cables should pull the levers on the carbs all the way to a built in stop, which should expose about 9 mm of the nozzle shaft below the adjusting nut. Air leaks into the manifold also cause hard starting along with problems getting the idle RPM and mixtures balanced. Vacuum advance diaphrams fail suddenly and throttle shafts wear (were the SU's rebuilt?). Just a thought. An high voltage ignition system & the wider plug gaps it allows will fire a lean mixture more reliable, so make cold starts a bit faster. Starting technique makes a difference, too. 3-4 seconds of cranking followed by a pause of about 5 seconds to let the gas in the manifold evaporate, seems to work best. Just crank and pause 'til it fires. Very light, quick pats on the gas pedal while it's cranking also seem to help. All an electric fuel pump can do is top up the float bowl levels before cranking starts. A mechanical pump in good condition will do that in in the first second or two of cranking, so the e-pump buys very little. The new gas goes in on top and the discharge is from the bottom, so fresh gas doesn't reach the engine until after it starts.

With only one leaking tube you might want to just have a radiator shop clean & repair the one you have. They'll put soldered plugs in both ends of the bad tube, a negligible capacity loss, and with the tanks off for that it's no big deal to make sure the rest of the tubes are clean inside. Salvaged radiators often need that much, and you know the history of the one you have. Re summer heat -- Just search old threads, this subject has been beaten to death. Early Z's have marginal air flow through the radiator at low speeds and RPM, and when not moving allow too much recirculation of heated air back to the front of the radiator. Adding an A/C condenser just cuts the air flow further. The most effective fixes I saw during 10 years in Houston started with a clean radiator and added various combinations of electric fans, fan shrouds, front air dams or BRE style spooks, and a seal (which can be just a sheet of plastic or coated cloth), to block the opening between the lower radiator support and the air dam or stock valance. Some owners put in oversized radiators, but those who started with air flow improvements got better results at equal or lower cost. My own A/C equipped 72 had a BRE style spook which included the lower seal, a fan shroud, and ran a 192 degree thermostat year round to minimize temperature cycling stresses on the head and head gasket. The only condition it couldn't handle was a large traffic jam on a 95+ degree day with a light breeze coming from the rear of the car.

The car should run with header and ports that don't match but you'll lose some power. Any sudden change in the port cross section, either shape or area, will create resistance to gas flow. A sudden contraction causes more resistance than a sudden expansion, so a round port header on a square port manifold causes more power loss than going the other way.

The driveshaft isn't the problem, but that mechanic may be half remembering a real issue with the 70's and 71's. They had a high half shaft U-joint failure rate and a mild high freq. vibration at freeway speeds which fit your description. The root cause was half shaft accelleration/decelleration (twice per revolution) caused by large U-joint deflection angles. In the 70's and 71's the inboard ends of the half shafts were 3/4 inch forward of the outboard ends as well as being higher. Starting in 72 the differential was moved back that 3/4 inch to reduce the U-joint angles. That's when and why the driveshaft got longer. It seemed to work, half shaft U-joint life was much improved in 72 and the high speed vibration was reduced so much that it wasn't noticeable.

Kirk, I had exactly the same symptoms with my '72 shortly after I bought it. The problem was crud -- a mix of water, rust, & bacterial slime -- in the tank repeatedly clogging fthe fuel filters and lines. Getting the tank cleaned fixed it.

There's no good hiding place in a Z. Under a seat hides it but makes changing CD cassettes really awkward. If you try it there make cure cassettes will clear the floor pan & carpet as they're changed. Clearances will be tight. A small changer will fit vertically behind a seat. It may limit how far the seat can be pushed back for long legs, and if it's too tall you won't be able to recline the seat back all the way. You can cover it with a loose cushion, blanket, an old jacket, etc. Horizontal mounting in one of the rear corners, with an old jacket thrown over it, may also work. Finally, you might be able to remove the glove box & hang a small changer behind the door using custom brackets.

Sticking valves -- can be caused by long storage w/o running and by running on very old, oxidized gas. Can happen with any head, E88's no more susceptible than others. Trying to clean 'em up on the car risks terminal head & block damage. Think valve head broken off inside a cylinder. Unleaded gas is OK.

Running while ether is sprayed in shows you have a spark. Could be one or both nozzles sticking, not dropping as they should when the choke in on, or the choke cable to carb linkage connection could have slipped out of adjustment (it's a weak connection, notorious for doing that). You should have about 8 mm of nozzle barrel exposed below the mixture adjusting nut at full choke (lever all the way back). If it's much less that carb is not getting full choke. Another possibility is a gum deposit blocking fuel flow. It could be anywhere from the banjo fitting & strainer to the tip of the nozzle, all places sprayed on carb cleaner can't reach. It's time to open up the SU's for a thorough cleaning & inspection, something you can do without disturbing any of the adjustments.

In 71 and 72 the code was also stamped on one side of each key. It's a thin & shallow impression, hard to see. Should be a letter followed by a 4 digit number.

My first time in a Z was in Albuquerque in January 71, driving my new '71 off the dealer's lot.

Dished pistons prove it was rebuilt. All original 240 pistons had flat tops. For ring info your best bet is to start to start calling aftermarket piston manufacturers, & local rebuilders in the hope someone will recognize that marking code. I'll risk a guess that you still have the original E3100 head and the OO put in dished pistons to lower the compression from 9.5:1 so he could use unleaded regular gas. DaveN HLS30-96167 now #00013, #14489, and #66826 in the past

Where?

Just search the web. Most carpet manufacturers have product photos on their marketing sites, some even explain the difference.

I had a similar experience with them last summer. I ordered two front brake rotors for a 72 Z. They sent two, one made in the US and one from China, both tagged with their part # for the Z. The US rotor fit, the Chinese rotor was a vented casting drilled for a 6 lug wheel and had a diameter about 1 1/2 inches larger.

Will, I'm a new member, found this thread last week. The DVD is a great project idea. If you're still collecting I have a few unusual items I can contribute: 1. The 72 transmission (F4W71B) FSM, Pub. # SM1E-4W7BG0 issued 15 October 71. It's a 22 page pamphlet covering the Z 4-sp and three similar transmissions, with a bit more detail that the tranny chapter of the main FSM. 2. The June 72 revision of the S30 Consumer Information pamphlet, Pub. # C13E-ALLMU0 3. The Datsun dealer list for North America, dated July 1970.

Re float bowl vent lines -- Their main purpose is to keep the pressure over the gas in the float bowl exactly equal to the pressure around the carburetor inlet. Any mismatch changes fuel flow, so those tubes have to be vented to the inside of the air filter.

A scene in "Corvette Summer" has a customized red Z on display in a Las Vegas casino.

Re early Z bumpers, here's a high spot summary 70-72 240: purely decorative, no government bump resistance standards. 73 240: slightly larger, stronger, further from sheet metal to meet the first year's interim federal standard. Early 74 260: much larger & stronger, w. shock absorber mounts to meet the "permanent" federal standard. Unibody redesigned (RLS series) late 74 & 280's: Mid-life styling update, structural design revisions.

At one time an aftermarket fan called a "Flex Fan" could replace the stock fan. The blades were chromed, and were thin enough to reduce their pitch at high RPM by twisting.

"Everything should be made as simple as it can be -- but no simpler." A. Einstein