Stanley

A bunch of coolant came out while the mechanic was messing with the hoses and he didn't bother to refill it ? Wow what a kook ! Notice that the earlier photo posted of the passenger side of the engine shows shows a short piece of hose with plugged end (why is the clamp on the end turned so you can't tighten it ?), but the later photo shows the side hose connected with the heater capped? Not that it makes a difference. Don't use those rubber caps, they deteriorate and fall apart quickly from the heat. Use a tapered rubber plug tapped into the tube instead, and clamp a silicon cap (mcmaster-carr) over it, OK? Cooling system uses all BSPT fittings. Use NPT and you'll bugger the threads. If you're ok with that, fine, if it doesn't leak. Temp gauge looks ok in the last picture of it. Edit: no it doesn't.

A bunch of coolant came out while the mechanic was messing with the hoses and he didn't bother to refill it ? Wow what a kook ! Notice that the earlier photo posted of the passenger side of the engine shows shows a short piece of hose with plugged end (why is the clamp on the end turned so you can't tighten it ?), but the later photo shows the side hose connected with the heater capped? Not that it makes a difference. Don't use those rubber caps, they deteriorate and fall apart quickly from the heat. Use a tapered rubber plug tapped into the tube instead, and clamp a silicon cap (mcmaster-carr) over it, OK? Cooling system uses all BSPT fittings. Use NPT and you'll bugger the threads. If you're ok with that, fine, if it doesn't leak. Temp gauge looks ok in the last picture of it.

A snail was at the Datsun dealership, talking to the salesman about buying a new Z car. Eventually they agreed on a price, but the snail said "I'd like you to do one small modification. I'd like you to change the "Z" emblem to an "S". The salesman asked, "Why do you want to do that ?" The snail replied, when people see me driving down the street, I want them to say "Look at that S-car go !"

Better get out and check while it's parked. Flashing indicator light doesn't necessarily mean it's working.

Maybe the carb tuning procedure in the Factory Service Manual would give better results than the procedure outlined in post #181.

Regarding the two line-three line issue, the third line is just a vent for the expansion chamber (hope I got the right name for it) that goes to the flow guide valve; don't see how it would make a difference. Regarding the "three reasons" for "percolation", in the modification manual that was posted, reason 1 makes sense, the other two seem a little iffy. However, that information applies to the flat top carbs used in '73 and '74. I'm not familiar with how those carbs work so maybe it's correct for them. My fuel pressure gauge (hooked to a tee between the mechanical pump and the custom fuel rail) seems to back up the percolation thing. On hot days, a few minutes after shutting off the engine, I've noticed the fuel pressure climbing slowly, past the usual 3.9 psi, to about 5 psi or higher. Then it drops suddenly. If heated gas vaporized and built up enough pressure to open the float valve, like the book says, that could explain it. I've also smelled gas after a hot start. If the float bowl is full when I shut off the engine, and the percolation effect pushes more gas in, that would explain it. My fuel rail is more isolated from the engine than the stock one, but maybe not enough. It seems like having a return line (I don't) would help the situation, but maybe not. Maybe no fuel return line would raise fuel pressure slightly, that might help prevent vapor lock (not percolation). Also, they already had return lines on the cars discussed in the modification manual, so apparently that didn't solve the problem. If the main cause of heat in the fuel lines is due to conduction from the bolted attachments to the engine, then it seems like insulating the lines would help keep the heat in.

I've got a '73 with AM/FM radio, stock speaker is at lower left side. The radio sounded horrible so I replaced the old speaker with one from PEP Boys for about $25. That made it a little louder and better tone. Still not much of a sound system though. IMO the stock radio has poor sensitivity, selectivity, and volume. Hitachi made good hi-fi equipment so I don't know why these radios are so crappy. My Sony ghetto blaster is 3 times as loud and gets 3 times as many stations. You could wire in another speaker on the lower right side, but I doubt if the stock radio has enough power output to drive an upgrade speaker system, without a booster amp.

I won't argue with the book. And regarding the AN fittings, I was sort of trying to discourage you from doing that in my previous post. Sorry, but it's more a nice, but time-consuming "finishing touch" kind of project for a Z car, than a solution for the vapor lock problem. A skilled technician with the right tools and experience building AN hose systems wouldn't have a problem (except maybe finding the right banjo bolts to fit the SU's), but it would be quite a project for anyone else. Why not just use good fuel hoses and clamps ? Way easier in my opinion, and just as good for keeping fuel lines away from heat sources. You could actually get the hoses, clamps, tee fitting, etc. installed yourself and be back on the road in a day or two. If you're too in love with the AN idea (I agree it would look cool) find the banjo bolts first. That will probably take a month. Also look up or measure all the fittings, getting correct hose sizes, lengths, and thread types for your project(another month). Then go to a place that makes hoses (for trucking, industrial, HVAC, race cars, etc.) and have them cut the hoses and install the fittings and adapters (20 minutes). Then install it yourself and you're done.

So, excessive heat in the engine bay causes rich condition fouling the plugs ? Can anyone explain that ? Because I don't get it at all, and I'm trying to learn something here. Vapor lock plus fouled plugs would make a crappy driving experience, but it's possible to have two or more unrelated problems at the same time. I remember posting a suggestion to get a synchrometer or unisync and set the mix with it, following the procedure in the FSM exactly. If you did that, at least carb settings can't have anything to do with the problem.

Some interesting ideas in the responses that hadn't occurred to me. D602-52 is non-emission spec distributor with 17 deg. initial advance, D612-53 is emission spec with 5 deg. initial. No graphs I could find in '72 FSM or '72 engine manual for D612-53, but the emission section has the settings for it, and also settings (and the complicated adjustment procedure) for the dual-point distributor that was standard in emission spec automatics, according to FSM. Maybe those are the only three stock distributors for L24.

AN hoses are safer, they won't leak if done right. But they need something threaded at each end to attach to, otherwise they're useless. If you have an old-style mechanical fuel pump on the engine you can unscrew the outlet hose barb and put a (BSPT to NPT) elbow or tee and hook the AN hoses to that with an AN/NPT adapter. Similar if you have an electric fuel pump with threaded outlets in the engine bay. You'll have to replace those stock banjo bolts with (metric) banjo bolts with threaded connections at the inlets. They're available, I forget where. Then you can hook it up to the AN hoses. Kind of a lot of plumbing.

C.O. was correct, problem back. Right T.S. only works part of the time (like me). Every time I've checked it while car was parked, if it clicked and the indicator light flashed, it was working. When the indicator flashed, but didn't click, it wasn't working.

Maybe they're shutting down because parts aren't available. The catalog seemed to have fewer parts each issue. Looks like I was asleep at the switch, two week camping trip to Northern CA. My car cover is shot. Called BD this morning but no more covers, 20 backordered and 20 on the way, no more after that. Anybody know who makes the BD-4000, part #82-136? Maybe better protection than the best MSA cover and cheaper.

If coolant level remains steady the gasket is probably OK, but radiator shop can test for a small leak / pressure. Easy to check for bad water pump. Let it warm up a little and remove radiator cap. Let it idle until it gets to 180F or whenever the thermostat opens. Look in the filler hole; you should be able to see the coolant flowing through briskly. You could also feel it pulsing in the lower radiator hose, but that's not as safe to check with the fan and belts spinning nearby. If not probably bad water pump or blocked radiator. If it's blocked you might be able to feel some cool spots on the core while it's running. How hot was the weather when it was happening ? Uphill or level ? Steady cruising or stop and go ?

My only experience with vapor lock in my 240 was a few years back, in Blythe, going west on the 10. Temp gauge showed the engine to be hot, don't remember exactly but at least 220F. Stopped at Albertson's to get lunch (sign at the bank said 117F), and couldn't start it until it sat about 20 minutes. Stopped at a motel; several other cars that came in were overheating. Left at 4:30 AM to beat the heat, but it was still 99F. Had to turn around on the Arizona side, overheating again. Found a little garage open on Sunday. They put a new fan clutch and I limped on to Tucson. A mechanic there told me to pop the hood which I found would drop coolant temp about 10 deg. Ordered an oil cooler and installed it before heading back, and got a Nissan thermostat. Back in the South Bay, head gasket gave out, found head was corroded, put JDM head and metal gasket, big aluminum radiator, flushed engine three times, added fan shroud, and removed plastic tube to cabin air vent to get more air in the engine bay (didn't like it blowing hot air on my feet anyway). Using mech. pump only, put filter by tank and removed the front one. Using a metal fuel rail that's more isolated from the engine, with no return line. Engine temp remains normal 180F even on a long upgrade on a hot day, like Palm Springs to the summit. Haven't had vapor lock, but I have a FP gauge (connected after the fuel pump) in the cockpit and I've noticed the fuel pressure bouncing (engine temp was still 180F) around on hot days when traffic on the freeway comes to a stop. So maybe that signals a pre-vapor lock condition. I wonder where that vaporization is happening on a carbed car with mech. pump. The steel fuel line comes under the car away from the engine and exhaust, which seems like a relatively cool area. If any vaporization happened in the float bowl, seems like it wouldn't do anything at all unless it all vaporized which seems unlikely. But I've seen the pressure dropping (and quickly rising again, measured right at the fuel pump, on the carb side. Normally it's steady.

Yeah, I saw those in the next drawer, they all seemed too big or too small.. Might be something better than the K-clip, though. I filed the ends to unsharpen them, mostly so I wouldn't scratch myself. The fold-over on the lap belt seems to cover it pretty well, though. Tried rubber washers before, worked for a while but eventually fell off.

23 cents at Ace hardware. Called a K-clip I think. Keeps the shoulder belt attached to the lap belt. Had to file it down a little on both sides to make it fit.

Right TS quit months ago. Tried sandpaper and VOM but no luck, no time to delve into it. Been using hand signal and being extra careful changing lanes. Now it's working again. Maybe the gremlins have seen the error of their way and are trying to make amends. A "new dawn" in the way mechanical things interact with us, maybe. There might be an explanation, but I've got nothing.

With N-27's (stock 240 displacement but some mods) had high end lean-out that I couldn't tune out. SM's and red springs fixed that for me but still too lean at low end tip-in, had to lower mix nuts to drive and idle without the effect Steve described, which seemed to cause excessive rich condition (judging from plug appearance), at mid-range I'm guessing. I think C.O. is correct in post 17. My car seems to be quicker on cooler days, which leads me to suspect a leaner mix is needed for performance on hot days. But any leaner and it craps out as stated above. I recently set the mix about a 1/16 turn leaner, after looking at the plugs, and I think it's got more power at mid-range, but I can definitely feel it's weaker (leaning out a bit) at low end, which hurts performance off the line unless I rev it up with my foot on the brake (AT) like at the drag strip. Not what I want to do for everyday driving, even if I want to keep up with a leadfoot in a Lexus. Maybe the solution is to modify the SM's by taking some material off at stations 1 & 2. But then the nice richness at top end would be reduced since the mix nuts would need to be raised (I think) to get it right at idle. Dunno what to do, except experiment. It's easy to make a float bowl overflow while setting the floats, especially the rear one. Maybe it just means they're set almost right, but not quite.

Thanks, good researching. My numbers might be a little off, used harbor freight angle meter and rounded off, so Nissan probably more correct.

Besides, the rollover dive looks way cool.

Yes, that's the whole point: equal fuel level at the nozzles. Need to think about that ten turns down; since it's almost impossible to get fuel levels exactly where you want them, a perfectionist might want slightly different mix nut settings for each carb to get equal fuel level at the nozzles, after setting the floats as well is possible in one day. Maybe tuning with synchrometer per FSM does that anyway. Five tries, twenty tries, of resetting the floats, eventually enough is enough. Car needs to be on level surface while setting the bowls, not a steeply sloped driveway. Besides fuel bouncing around as Blue stated, it also goes up and down a couple mm as the valves open and close. If you have sight glasses attached with the engine running you can see it. I'd like to see that TS73-10, didn't know it existed.

Found this CAD drawing I did a couple years ago to help understand the tilt / fuel level issue - why different levels in the bowls are required to get equal fuel height in both nozzles. In my opinion this is why Nissan changed the ears and valve length on the front carb for the 3-screws in 1972. I've got the 72 engine manual, but it doesn't mention different settings, and as far as I know there was not technical report about it. Wonder why. Maybe it was a time-line thing, since the carbs were changed to flattops in 73. The first time I opened the front float bowl I found a really bent-up float. Maybe some previous mechanic got mad and used the "ignorance and brute strength" method on it. I've used that method myself, with mixed results. inh

Tilt of the engine requires rear carb 2 mm higher fuel level for same fuel level in both nozzles. There's a thread with diagrams and the trig equations that illustrate it. Touch up the sticking float with sandpaper - that cured a sticking one for me.

Didn't know it worked like that; from now on if I plan to buy anything from a company that advertises here I'll use the link instead of going from Google. What if I just want to look instead of buying? Does that help the site?