DaveN

Mark, Do you have flat top (original 260) Hitachi's or a round top conversion from an earlier model year? The flat tops have true chokes, the round tops use a movable main jet instead of air flow restriction to get a richer mixture for cold starting. Flat tops can be made easier to start when cold by fudging the choke butterfly adjustment a little toward fully closed. Conversely, cold starts will be slow (or impossible) if the choke butterflys aren't closing quite far enough. It's a sensitive adjustment, hard to make reproducibly because you do it by bending a wire piece in the linkage. Flat tops also have a special starting jet -- another fuel passage that can become blocked by sludge in the car is stored for months/years with fuel in the carbs. Round tops have a limited cold start enrichment range. The linkage on the carb should allow 10.5-11mm of nozzle drop from nominal zero (top of nozzle flush with bottom of venturi). 2-3mm of that, depending on carb model & setup, is used for for the hot mixture adjustment; the rest is available for cold start enrichment. The final link to the nozzle, a bent steel strip, can be straightened a little to get about one more mm of max. nozzle drop without binding. The only other adjustments available are to make sure the "choke" cable adjustment is giving max nozzle drop in both carbs in the full choke position and to fudge the float levels upward a little (and run a bit rich all the time). If this isn't enough (it wasn't for my '72 on the coldest mornings in Wilmington, DE) a kettle of boiling water poured slowly over the carbs and manifold just before starting may make the differrence. Both lack the "accelleration pump" that fixed venturi carbs need, so there's no way to prime a cold engine by stroking the gas pedal before turning it over. That makes them slow to start when cold, you have to prime them by letting them turn over until there's enough fuel in the manifold to get an ignitable mixture into the cylinders. It helps and is easier on the battery to crank in 4-5 second bursts with pauses of several seconds between (to let gas in the manifold evaporate). Most older carbureted cars become harder to start after sitting for several days because sitting gives the high volatility "cold start" fraction in the gas more time to evaporate from the float bowl. It's especially noticeable in early Z's because you can't compensate by giving the accelleration pump an extra stroke or two.

Jon, Under most conditions well made and correctly aimed H-4 headlights send less light toward an oncoming driver's eyes than sealed beams (and most late model high tech headlights). They're brighter than sealed beams when something -- heavy load, cresting a hill, etc. -- raises the low beam cutoff above an oncoming driver's eye level, but even then the street spec 55/60w bulbs aren't as bad as most late model (and legal) HID headlights. The reflector and lens design controls the light distribution, so unless someone can share experience with the the exact make and model you have you'll just have to mount and try them to see how yours will perform. You can use 55/60 bulbs with original Z wiring in good condition, but it's marginal -- fuses will run a bit hot even when new, can generate enough heat to melt the fuse box when their fusible strips begin to deteriorate. The upgrade harness mentioned above will fix that and increase light output. Don't even try 80/100w H-4's bulbs with stock wiring. I've used nothing but Cibie H-4's on my Z's since '72 (with the standard 55/60w bulbs, never the off road 80/100w version). Never had a problem from law enforcement. State safety inspectors sometimes claimed the H-4's weren't aimed properly, but usually relented when pointing the lights at a wall proved that aim testers designed for US sealed beams weren't accurate with H-4's. (The H-4 lights didn't have mounting points for the testers molded into their lenses.) The most I ever had to do was re-aim them after an inspector insisted on adjusting the aim until his machine said they were right. It may have helped that European spec H-4's were always legal for police and emergency vehicles (including the president's limos, which used them) and that a published California highway patrol test report (ca. 1980)recommended they be made legal AND MANDATORY for all cars registered there because their performance was much better than any sealed beam headlight.

All the early OEM fans had clutches. In the early '70's you could get aftermarket replacement fans with no clutch, and some owners switched after clutch failures because they cost about $100 less.

www.carfiche.com has the Z parts microfiche online. Free access for all.

Listen to your mechanic. When the head warps the cam bearings are usually pulled out of alignment. Running with it that way will fatigue and break the camshaft. Trying to slide the cam in and spin it is an alignment test. If it passes you're OK, just shave the gasket surface and go. If it fails the test go get the other head. The warped head needs to have new cam bearing blocks fabricated and align bored after they're bolted on.

The factory wrap wasn't asbestos, it was fiberglass with a reflective foil skin. But... I don't remember it having a woven layer under the foil like the stuff in your photo. In most places 70-72 Z's didn't have a percolation (similar to vapor lock) problem when new, but central AZ may have been hot enough to be an exception. They have had problems in hot climates since the 80's -- search old posts, many complaints -- because gas vapor pressures have been raised. With no insulation chances are you'll have the problem next spring.

Fram PH8A and DG8A are correct. You can cross reference other brands to those.

Posts a few months ago advised using diesel rated oil or an additive supplement like STP in all L series engines because valve train wear problems have started showing up since ZDDP (an anti-wear additive) levels in oil for gasoline engines were cut by half about a year ago. Just a thought.

Do a Google search for "E85 conversion". You'll find lots of ads for conversion kits and several articles warning that they're all illegal because none has been certified to meet emission standards. DIY conversion is also illegal unless you can prove (testing costs $$) that emissions are no higher than the pre-conversion standard for the same model. Dig deeper into E85 and you may not want to touch it. The net energy gain is low (recent published estimates are in the 20-60% range for ethanol, around 100% for biodiesel with potential for improvement as higher yielding oil crops are found/developed) and we don't have nearly enough unused land or water to grow the amount of grain we would need to replace all/most of our gas supply with ethanol. It's mostly a windfall for corn growers -- a fat federal subsidy makes ethanol production profitable and corn prices are way up because of it.

Arne is right, A/R sold Libres unpainted. So, there is no "correct" color. In their heyday Libres with painted spokes were a popular choice of the (relatively few) owners who wanted that look from aluminum wheels. The most popular colors where I lived then (central NC) were shades of gold/copper/bronze and to match the car's body color.

Re cam -- Good advice here: http://www.geocities.com/zgarage2001/engine.html High lift, short duration for 1500-5000 RPM. Be careful to get the metallurgy right. Re heads -- E88 to keep the compression ratio up.

Assuming you have a strong spark, the symptoms sound like you're not getting "full choke". It's easy to check with an inspection mirror. At full choke you should have about 8mm of nozzle barrel exposed below the adjusting nut (linkage on the side of each carb stroked to or nearly to it's built in stop.) Cables slip out of adjustment easily where they attach to the carb, that's and binding inside the cable are common causes of under choking. Because they don't have accelleration pumps (and are side drafts) early SU's need several seconds of cranking when cold to get enough gas into the manifold intake manifold to produce a flammable mixture in the cylinders. It helps (and helps the battery) to crank 3-5 seconds and then wait 5 seconds or so before trying again. Very light, quick pats on the gas pedal while cranking also seem to help sometimes.

This site is a good source of SU info. It's run by British car buffs, but they admit the best maintenance articles available were written for Hitachi SU's. http://www.teglerizer.com/sucarbs/index.html Nozzles come out easily. Just take out the one screw at the bottom that attaches the linkage and disconnect the gas feed tube. If they weren't sticking they would fall out in your hand. Sticking can come from a varnish accumulation if the carbs haven't been cleaned in a while, from the "anti-stick" coating on replacement nozzles, or from badly bent needles. If they need cleaning you only need to remove the nozzles and dome/piston/needle assemblies to have access to all the areas that collect dirt. The carb bodies can stay on the car. Here's the history of the nozzle coatings: The earliest Z nozzles had no coating and were sensitive to varnish/dirt accumulations. In late 71 or early 72 Datsun began using a thin black PTFE coating, but found it would begin wearing through in a year or less of service. They switched all replacement nozzles to a more durable but slightly thicker (clear, green tinted) coating in the mid 70's. That coating is soft and sometimes a bit too thick, making the nozzle OD a bit too big for the bores in the carb bodies and giving a sticky fit. When that happens you have to polish the nozzles by hand (with rubbibg compound, hard finish cloth, etc.) to reduce the coating thickness. Bent needles are the least common cause of a sticking problem. The wear they cause isn't repairable, both needles and nozzles have to be replaced. (With 72 carbs you can ignore instructions about aligning nozzles in the carb bodies. That only applies to 70-71 bodies.)

Good performance tips can be found here, especially re cam swaps. http://www.geocities.com/zgarage2001/engine.html In a daily driver go for as much lift as valve-piston clearance allows and only a little more duration than stock (to preserve midrange torque). A strong midrange is the key to lively street performance because it's used a lot more than the extreme top end. Re SU's and air filters -- The stock air filter housing is very good, actually better that most aftermarket replacements. The stock element is good, too, (until it gets clogged by dirt), but an oil wetted foam replacement element can flow a bit more air and hold more dirt. Avoid any aftermarket filter that doesn't have both a radiused inlet air horn similar to the stock housing and a connector for the float bowl vent hose. You need the streamlined inlet for good air flow and float bowls vented to the clean side of the air filter for proper mixture control. I have tried stock, 70-71 spec (N-27) and SM needles in a mildly tweaked 72daily driver. N-27's (slightly richer than stock) worked best. Had to lean out the SM's as much as I could with set up adjustments (low float levels, no water to the carbs) to make them tolerable, and they were still richer than optimum for performance or street driving. Re headers and exhaust systems -- Well made headers add a little power above 4000-4500 RPM, but aren't quite as good as the stock manifold up to 4000. A free flowing 2.25" or 2.5" exhaust pipe and muffler are a must, headers are optional. (How deep are your pockets?) If you keep the stock manifold either remove the air injection tubes and plug the holes or cut the tubes off flush with the exhaust ports. (The air pump takes about 6 HP at the redline, 2-4 HP in the midrange. With tubes cut flush and a good 2.25+ inch exhaust system the air injection doesn't add enough back pressure to be noticed.) Re ignition -- L24's perform best with lots more spark advance than the original spec. How much more depends on what's been done to the engine and the fuel being used. All the engine will tolerate without pinging is likely to give the best performance. Electronic ignition gives better timing control, less misfiring, and usually a better advance curve. Lot's of posts here & in other forums about which works best. If you have deep pockets buy a book titled "How to Modify Datsun 510, 610, 240Z Engines and Chassis" (I may not have it word for word, but that's close) and find a reliable performance shop to do the valve pocket relieving and block eyebrowing it describes. An E31 (70-71) head is best for this mod because the stock compression ratio was higher, and you lose a bit of compression when the valve pockets are opened up. These head mods done right add at least as much performance as a high lift cam and 2.5" exhaust, and you can still do those things to get even more power.

It was a light grayish green.

That's the branch of the "engine room" wiring harness that connects to the instrument harness. For a picture go to www.carfiche.com, navigate to the S30 parts list in their microfiche section & find section 24. PS: The battery cable in the picture looks like an OEM negative cable, with an engine ground and a smaller chassis ground to the firewall.

A spring in the choke linkage on the side of the carb holds the nozzle up. The cable can be disconnected but the final link to the nozzle has to be attached. If it isn't the nozzle can drop far enough to cause an extremely rich mixture. 3 possible causes in the float bowls -- 1. Sticking (open) or defective needle valves. 2. Defective floats. They're rigid urethane foam with a very thin skin. If defective or damaged by rough handling liquid gas can fill some of the cells, making the float lose bouyancy. 3. Levels set much too high. With the bendable metal arm on the float just touching the needle (but not compressing the spring in it) the measurement from the other end of that arm (on top of the float) to the underside of the bowl cover should be 13.5-14.5mm. That's 1 mm higher than the spec in the 70-71 FSM, per a tech service bulletin issued in early '73.

The tips here include good info on cams. http://www.geocities.com/zgarage2001/engine.html In brief, more lift helps power but there are mechanical limits on what is possible. More duration shifts the power band to higher RPMs but usually cuts the peak torque a bit. Stage I and stage II are the best matches for the RPM capabilities of an otherwise stock L24.

Exploded view... go to carfiche.com The microfiche section has the S30 series parts fiches. Section 10B covers the 73' flat tops. This site is primarily for British SU owners, but has good "how they work" and how to maintain material, much of it applicable to all SU versions. http://www.teglerizer.com/sucarbs/index.html

Searches of old posts here and on zcar.com should give enough info to tell you which head to look for. Briefly... E3100 heads were used in 70 and 71. If unmodified the compression will be about 9.5:1 on 70 through 72 blocks and nearer 10:1 on 73 blocks because the piston crowns were .030" higher in 73. Their weakness is a tendency to miss and raise HC emissions at idle, so they often have trouble passing emissions tests. E8800 heads were used on 72's to fix the miss at idle problem. Compression was also lowered to allow use of 91 RON regular gas. E8800-SV heads came on 73 240's. Combustion chambers were a bit larger and piston crowns raised to give the same compression as 72's.

Dry ice blasting has been available to industry in the US for about 20 years. The first equipment supplier, and I think the inventor, was based in Canada. It is non-toxic if used with plenty of ventilation or a -- high CO2 concentrations in air are toxic if breathed and in prolonged skin contact. It is not abrasive to steel and is very good at removing paint and tar like fouling because it cools the stuff enough to make it brittle. Just be careful about cleaning things that could be damaged by extreme cold or fast, uneven cooling.

First, is the problem a difference in how quickly the pistons move to new positions? ....or are they rising/falling through different distances as RPM's change? And... do you have round top or flat top SU's? If it's a difference in how far the pistons move the first check needs to be for equal/unequal air flow using a meter like a UniSyn. Unequal air flow could be caused by a linkage adjustment or internal engine problem, or by altered (by a P. O.) & different piston weights or a missing or too strong downforce spring. In any case you need the original piston weight and spring downforce to get the correct venturi vacuum and mixture. If it's a piston velocity during movement problem swapping the pistons is a good place to start. Pistons and domes were assembled as matched sets to get the right clearance (for correct air leakage rate). If your front and rear diameters are a little different the P. O. may have caused the problem by swapping them accidentally. Other ideas -- 1. Try moving the pistons in the domes by hand with both off the car. If there's more drag in the rear set you have a clearance/dirt/mechanical damage issue there you'll have to fix. This could cause either a steady state height or velocity of movement difference. for a velocity of movement problem only -- 2. Make sure the dome to air cleaner vent holes in the rear carb body aren't clogged. You need them to vent the space under the top (larger diameter of the piston. If they're blocked movement will be slow in both directions. 3. This doesn't fit your symptoms but is a worthwhile check on a newly purchased car. Are the damper valves -- the brass parts at the ends of the "dipsticks" -- both intact and clean? They work like shock absorber valves to resist fast piston movements. You can check for unequal valving by swapping dipsticks with the oil levels normal & checking for differences in piston movement. Good luck

25230-E4100 is for the hatch glass heater.

Will, I can supply a 74 (260) FSM if you need one. Would have offered it before, but thought the ebay "prize" had met that need.

David, Your symptoms -- running lean, worse at low RPM -- suggest an air leak into the manifold. It's time to start troubleshooting things like the throttle shafts, vacuum advance, brake booster, and BCDD actuator diaphrams. Re SU needles -- The 3 screw round tops used on 72's came with N-58 needles in automatics and slightly richer N54's in 4 sp cars. All 4 screw SU's, used in 70 and 71, came with N-27's.