240ZMan

I would like to go with more, too. I tried 20 degrees, but was getting pretty strong pinging around 4500 rpm, and maybe higher, just couldn't quite hear it clearly over the engine. I'm just wondering what I give up by not getting the vacuum advance at part throttle. I'll guess it translates into a bit less fuel economy, but given I can set the carbs a bit leaner and still keep it driveable this way, perhaps it's all a wash. Wish I had a real dyno...

Lately I've been running my 73 240 with roundtops as lean as I can to deal with some idle issues. One side effect is that applying the throttly gently, such as going around a corner slowly in 2nd gear, results in a jerky response from the engine. It's just not possible to accelerate gently and smoothly at the same time. So I was playing around with things and removed and plugged my vacuum advance. I also advanced my timing from about 8 degrees to 15 at idle. Interestingly, the jerkiness at part throttle is almost completely gone. And I find it pulls to 6k rpm just a little stronger as well (due to the extra advance, maybe?). So my question to the group is what am I giving up? At the risk of sounding a bit cynical, rarely in life is there a free lunch:finger:

The question is if the ignition module you're using can handle the resistance of that coil. A lower resistance (higher voltage) coil puts more load on the module. I don't know the specs of what you're using so I can't give you a specific answer. In my case I went with the Pertonix ignition as well as their higher voltage (lower resistance) coil. As near as I can tell, if you know the resistance of the coil you want to use, and the module says it can support that, you should be ok.

Matt, I'm going through that exact same issue for myself right now. I talked to a local Z-only mechanic and he said he'd recommend the 240 over the 280 as it was lighter. But I'm actually going to stick with the 280 because when I last had my 240 off, the channel for the key wasn't as pristine as I'd like. And if that pulley gets loose at speed, you can pretty much throw away the crank. In fact, that's how I got my E31 head. The PO had that happen just after he had rebuilt the head. He decided to scrap the whole motor and put another one it as that was cheaper. So his misfortune was my gain. So I'd use the condition of the two pulleys to make my decision.

I think the answer to the question about auto vs. manual is like a lot of other things in Z land: It depends on what you want from your Z. For me, mine is a 3rd car and NOT my daily driver. Also, it's something for me to apply my "creative juices" towards. If the weather isn't good, then the Z stays in the garage. If it's going to be a long trip, then I take one of our newer cars that is quieter, get's better mileage (at least for one of them), and don't require shifting. But if it's Saturday morning and I'm going out to run errands and have a little fun :classic: , then the Z is my first choice. Of course, I am fortunate to have the choice of other vehicles. If the Z was my only vehicle, and I had to use it for work as well, then I'd have to switch to an automatic. I get too many cell calls during the day and shifting, steering, and holding a phone just don't go together safely. So it all goes back to what YOU want from YOUR Z. Either way they are fun cars, the Z community such as this website is a great group to be hanging around with (at least virtually), and you can customize the car to what YOU want. My .02.

I have a 73 240 and am consididering doing the electric fan swap. I've measured the clearnce between the radiator and the tip of the 4 bolts on the water pump and it's just about 3". I don't think there has been any accident for this car either. 3" is less than the height of any 12" or lager fan that I've been able to find. Most want at least 1" of space in addition to their height which means I'd need almost 5". How are the rest of you doing it?

I was going to work on the AC box under the passenger side when I noticed that one of the relays mounted up there was very warm. Given I hadn't driven the car for a few hours that wasn't a good sign. Turns out it's the relay that controls the fuel pump. With the new wiring for the new alternator, I guess it's always "on" (which explains why my fuel pump comes on when the ignition only is on). Unfortunately the wiring diagram in my factory manual only shows the fuel pump and does not include any of the circuit that shuts the pump off when the engine quits running. (BTW, I surmize that it quits when the alternator stops producing electricity, not when the oil pressure drops as I said earlier). I'm guessing that given the electric fuel pump was added by the dealer on the 73s when owners complained about vapor locking, it was probably a field-fix that wasn't documented properly in the factory manual. So my question is if anyone has the wiring diagram for the fuel pump circuit? Or perhaps the circuits inside the voltage regulator and the alternator (old one). If I had that I think I could figure out how to wire it up.

One "unintended consequence" is that now when I turn on the ignition, the electric fuel pump turns on. This is even before I start the engine. Used to be that until the oil pressure built up (greater than 5 psi?) the pump stayed off. I understand this is a safety feature so that if there was a crash, the fuel pump would shut off when the engine died. Thre is a part of me that likes this new "feature" as I had a problem getting started a few times when there wasn't enough fuel in floats. I guess my oil pump doesn't generate enough pressure when cranking the engine to turn the fuel pump on. Of course, there is a safety issue now. Can anyone with a 73 running with an electric fuel pump tell me if their pump comes on with the ignition? And suggestions on what's going on here?

Just put the new alternator in tonight. My old regulator (that was only a few months old) had the battery voltage at 13.8 V when all was warmed up. The new alternator is at 14.6V. Pretty sweet to get almost a full extra volt! Dash lights are noticeably brighter :classic: And at idle, I can turn on the headlights, fog lights, and fan on high, and the ammeter stays right at 0, just as it should. I highly recommend this to all of you with older Zs.

http://www.classiczcars.com/forums/showthread.php?s=&threadid=5997 I'm getting ready to swap an '80 60 amp alternator into my '73 240 and am using Bambikiller's excellent writeup as a guide. But I have a question that I don't see answered in it. I've attached a picture of the new alternator. You'll see a yellow arrow pointing to a connection that isn't in the write up. Anyone know what it's for? The reason I ask is that I took the alternator to a parts store and had them test it. Their configuration didn't show connecting that pin and they were unable to get any output from the alternator. So I went to another store and their configuration did use the connector, and the alternator tested good.

Branden, I'm attaching an engine calculator that will help you answer your question about CR. But as you'll see, you need to know a few more things such as what type of pistons (flat top vs. dished), type of head (E31 vs. early E88 vs. late E88), and head gasket you have. Perhaps the previous owner can help? As for expected HP and torque, I'm afraid I can't help you with that. Good luck. lengine.zip

This joke was forwarded to me today. I don't know who first told it so I can't properly credit... A few days ago I was having some work done on my car at my local garage. A blonde came in and asked for a seven-hundred-ten. We all looked at each other and another customer asked, "What is a seven-hundred-ten?" She replied, "You know, the little piece in the middle of the engine, I have lost it and need a new one.." She replied that she did not know exactly what it was, but this piece had always been there. The mechanic gave her a piece of paper and a pen and asked her to draw what the piece looked like. She drew a circle and in the middle of it wrote 710. He then took her over to another car which had its hood up and asked, "Is there a 710 on this car?" She pointed and said, "Of course, it's right there." If you're not sure what a 710 is, click here.

My 73 has the dealer installed AC. Like many, it doesn't blow much cold air, and I've confirmed that it does have a full charge of refrigerant. I'm getting ready to swap in a 280 motor from an '80 280zx and I received it's compressor in the deal. My question is if the new compressor is compatible with my existing system and if it would improve its performance. Given I have the engine out, there will never be an easier time to make the swap!

When installing a new oil pan gasket, what's the recomendation for using an adhesive, such as the Permatex products? In the past I've had good luck on other vehicles just cleaning the surfaces and installing the gaskets by themselves. Right now I've got the engine out on a stand so I want to do it right while it's still easy:classic:

http://www.classiczcars.com/forums/showthread.php?s=&threadid=10045 This link will take you to the thread when i had a something like you describe. In the end I loosened the front diffy mount and sparyed WD40 all over and the creak went away. But as you will see, most of the time the problem is with worn mounts and/or bushings in the moustache bar.

An update: This weekend I made some changes that have improved things, but not completely solved the problem. I put longer studs on the intake manifold and switched to the thicker insulators between it and the carbs. I also plugged the coolant lines that heat the intake manifold. I also took the mechanical fuel pump out of the fuel path and am running entirely on the electric. I did this so that the fuel wouldn't get the extra heat added by the mechanical pump. I also retuned the carbs to get them as lean as possible. They surge a little until everything is completely warm. I get a lean pop downshifting from high revs now and then. The result is that today where it was about 65 and sunny (the warmest it has been since last fall), when I let it idle for long periods, the idle would periodically stumble, but not nearly as badly as it used to. Something is still causing the mixture to fluctuate more rich when hot, but it's not as bad as it was. I have a fuel pressure gauge mounted semi-permanantly now, and pressure is staying around 3 psi consistently. Any ideas? BTW, I'm using Marvel Mystery oil for the dampers, but don't know how that would affect this problem.

My 73 has the original AC system installed. The PO had recently charged the Freon and I did get some cold air, but not very much. While I like AC, I really don't need it for this car. I'm getting ready to switch engines, and so I need some advice on what to do with the Freon. Assuming I'm going to remove the compressor and not reinstall it, is it worth it to go to an AC specialist and have them remove the Freon vs. just letting it vent? BTW, I haven't run it (no belt on it right now) since last summer, so I don't know how much, if any, is present. Also, I know Freon is very expensive. If I take it in to be "captured", is there some way to save it so that if I wanted to reinstall the AC later, I wouldn't have to buy it again?

Moyest, sorry to hear you are having a similar problem. But I'm not sure ours are the same issue. My engine is basically a stock 73 with round top carbs. I have the stock heat shield in place as well. I have been playing around some more and have discovered something interesting. I have both a mechanical and electric fuel pump. I put a switch in the cockpit to control the electric because it's rather loud and most of the time it's not needed. As a test, I bypassed the mechanical pump and ran only off the electric. I've found that if I let the car idle long enough to buld up heat in the engine compartment, the idle will begin to stumble. The engine acts as if the mixture is suddenly very very rich. What's interesting is that if I turn off the fuel pump, within 30 seconds the idle is back to normal! If I turn the pump back on, the stumble returns almost immediately. I have a fuel pressure gauge temporarily installed and can see that the pressure stays around 2-3 psi with the pump running. Today I put a pressure regulator in but it didn't make any difference regarldless of where I set it. I've double checked my float levels and even swapped a different set of floats as well as needle/seats from a spare set of carbs I have. Still no difference. At this point I am completely stumped. How can the warming of the carbs cause them to go rich, and then recover by turning off the fuel pump? Any thoughts would be greatly appreciated! :stupid:

I have a 73 into which I'm going to put a 280zx motor. To start I was thinking of using my SUs, but was wondering about later putting the FI on. What is the issue that requires a new tank? And from what model year? Thanks.

So it boils down to 2 choices for me: 1) use the N47 head with its stock exhaust manifold and find a way to get the aftermarket exhaust (2.75") to work on my 73. 2) use my E31 head with the 73 stock exhaust manifold and the existing exhaust (Monza 1.75" more than 20 years old). Both will use my rebuilt roundtops. Which would you choose?

Thanks Zeiss150, that's helpful. Sounds like it's a wash between the two if I don't rebuild. Of course, I do plan to do a rebuild later. I think then I'll go with the E31 head, larger valves, more agressive cam, thinner gasket, keep my SU carbs, and a better exhaust and life will be good. :classic: In the mean time, it seems like whichever bolts up to my existing exhaust will be the better choice. I read somewhere that the flange on the N47 exhaust manifold is different than for the E31. Anyone know about this? Also, I have a chance to get the exhaust from the donor car. He says it includes a Dynomax super turbo muffler and 2-3/4" mandral bent aluminized pipe 1 year old. Anyone know if I can use this with my 73? The donor is an 80 280z. I'm sure it won't just bolt up, but if it basically fits and I just need to attach new hangers that would be sweet.

http://www.classiczcars.com/forums/showthread.php?s=&threadid=11830 I asked a similar question earlier, but didn't get an feedback and since then have learned more ... and still have questions. I am getting an 80 280z engine complete with the FI. My current plan is to put it into my 73 240 and run with my round top carbs. I have 2 main questions: 1) am I giving up any HP by using carbs vs. FI? 2) my existing engine (200+k on the bottom end and bad compression) has an E31 head with unknown mileage. The new engine's N47 head (and block) have about 80k miles. Which head should I use I've read that the N47's exhaust ports aren't the best shape and that the exhaust manifold won't bolt up to my existing down pipes. I've also read that the E31's valves are smaller. It would be easier and cheaper I think to put the E31 head on with my current manifolds and exhaust system. Cheap is important right now as I need to wait until later to make further improvements for breathing. Any advice would be much appreciated.

I may have a chance to pick up an '80 280zx motor to swap into my '73 240. The only way I can do this project at all is to keep the costs way down. I have a few questions as I plan this out: 1. Should I keep the existing FI for the new motor, or put my 72 round top carbs on it? I like the idea of no smog with the carbs. FWIW, this is a weekend car, not a daily driver, and I am very comfortable working on the carbs. What sort of difference in top-end HP might there be? 2. Can I bolt my existing 240 clutch parts on to the new motor? They are relatively new and in good shape. For now, I don't plan to do a 5 speed swap. 3. Can my existing 240 radiator handle the load? I had a few cracks fixed last summer and the shop said it was otherwise very clean. Will my existing hoses bolt up to the new motor? 4. Can I keep my existing radiator fan and shroud? 5. What about motor mounts? 6. What else should I be thinking about? Thanks in advance! Daniel

As the original starter of this thread, I thought I'd let you all know how it finally worked out for me. As I couldn't find anything wrong under the car, one day I loosened the front diffy mount, sprayed WD40 all around, and tightened everything back up. Clunk is gone. Go figure...

If you mean the one between the manifolds and the carbs, then yes. Of course, it's for a 73 and I have 72 carbs, but I didn't think that would matter.