ajmcforester

I'm not certain if the one Bonzai Motorworks have is exactly the one you are looking for but thought it might be worth passing on. They have one for 70 and one for 71. Sorry I didn't see one on the site for a 73 you might contact them they have more than they post. http://www.zzxdatsun.com/catDecals.php

Replacing the PCV valve is a good idea. I ruled it out since you stated you stated you notice one half of the engine was worse than the other. Back fires are usually caused by lean conditions, with the carbs on the Zs you can get some great explosions if one is really rich and the other is lean. By the way the friend that gave me that advice about the rings, only raced his car so it might be a little soon for a street car, but if the rings didn't set correctly they would be done by then also it gives a good indicator when to start checking compression as routine maintenance. With how these blocks are if you catch it early enough you can get away without re-honing the block when putting in the new rings.

I add a little penetrating oil

You have done more than most so far the next step is to do a compression test. I was recently in a discution helping someone do this and get the best results I hope this link will help. Also you might want to do a leak down. http://www.classiczcars.com/forums/showthread.php?p=324506#post324506 What concerns me is a rule of thumb I was given of replacing the rings every 120,000 with these cars and ?54,000 does not sound good. Lead additive is not for the oil but the gas these engines have brass or bronze guides and seats on the valves. What lead or lead substitute does is protect the guides and seats. When you put harden aluminum seats it fixes this problem. Also how did the valve seals look? My guess right now is either head-gasket, valve guides, and/or rings. However lets do the checks before taking the engine apart their are other probabilities, also getting some data before doing that will let you know ware to look.

OK I've felt stupid to many times by giving advice to find people haven't done the basics first. This can be several things, and I can help you start to diagnose the problem. First more information is needed. How many miles? Was the engine rebuilt, and when? If harden seats have not been put in have you used and lead additive? What color is the smoke? When was the last time the valves were lashed (check and adjusted for cam clearance)? Was their a lot of adjustment? When was the last time a compression test was done if a all? Any coolant or other fluid loss? Since you mentioned oil smell what weight do you use? Any engine based mods including electrical upgrades?

Wow another Z not scared of a little rain. All my Zs have never been hydrophobic. Just got to spray it all down, and clean the oily grime off after the drive.

Arne is right you need to give the engine the least amount intake resistance as reasonably possible. If you test low again try taking the top of the carb off and take out the piston and see if that helps. You need the throttle fully open otherwise your numbers will always be low. Make sure the battery is good and fully charged so you get the proper RPM

Great information, my engine tested good on all tests and I run 10W-40 with no oil loss. However my engine has indications that it has new bearings, and rings, I know the cam has new bearings. I have used on other cars heavier oil when the engine started to louse oil, and isn't a bad thing the since the tolerances in the engine change over time allowing for heavier oils. Have you tried lighter oils and if so did you have any oil loss? Your test is close to how they state to do it. Hear is how it is stated to do it in the 72 factory manual. With the engine warm, all spark plugs removed and throttle and choke open.(I don't think you need the choke open with SU carbs the text cover 3 different setups) No cylinder should be less than 80% of the highest cylinder. Excessive variation between cylinders, accompanied by low speed missing of the cylinders or cylinders which are low, usually indicates a valve not properly seating or a broken piston ring. Low pressure, even though uniform, may indicate worn rings. This may be accompanied by excessive oil consumption. The only thing different was they pull all the plugs which would allow the engine to spine more freely. Note they state even pressure like you are getting indicates worn rings. Also it may(it don't mean you will) have excessive oil consumption, which you might with a 10 weight oil. I might try pull all the plugs and do one or two cylinders to see what number you get, since they all tested about the same the first time. Lastly a leak-down test is a pressure test were you hook up a pressure gauge and see how much pressure is lost over time. This is how I was told to do it with a pressure gauge connected the the spark plug hole at top dead center or close to it to make sure the valves are completely closed, bring the pressure in the cylinder to 100 psi and see how much is lost over 1 hour and that is your % loss. This is not in the Nissan manual, to give you some reference numbers mines tested at 94-97%, my first Z was around 90% with the same gauge with about 40,000 miles of use, both engines were in top shape. On a Ford 302 and Chevy 350 80-85% is considered the threshold for a street engine. This is just another test to see how the top end is, a leaky valve or worn rings will cause leaks. Also the test has about a 5% variance depending on engine temperature changes, air temperature change and how long the hose and brand of gauge. What I look for is consistency, and number above 80%.

Great point if you didn't follow the manual the nubers I gave you might not work as a compairison. Also tell us more about the engine, any mods? Did you do a leak down yet? Any oil loss, smoke at the tail pipe, gas smell from the oil? What weight oil?

According to the 72 factory manual you should be around 171-185 PSI at 300-400 RPM with the SU-carb setup; so I say you are very low. A rule some old Z guys gave me "plan to replace the rings every 120,000 if you change the oil and do all the proper maintenance. You are more than likely won't need to re-hone the block." I was also told that compression tests under 100PSI means re-honing the block (as a rule of thumb). Your at 109, and have lost 25-30% of your compression (assuming the compression numbers are the same for a 73)so I think it might be time for some engine work. Please check to see what a 73 compression should be first I don't have a microfiche reader at home so I can't check the 73 manual, and the library is closed now.

I've always wanted a protection film I could just peel of when it gets worn out, but they seem to push these hard adhesive based films. Well I'm restoring my car right now and was looking at kats website and was noticing a blue protective film being used. Well I liked the idea so I started trying to find the product and started to learn a bit about protective films. I got several sample products that I tried and found two I really liked from Surface Armor. I did some simple test to see what the products could handle also. I was going to start a forum soon and go into a lot more detail about what I found. I'm planning on writing a detailed synopses to start it off. Surface Armor's product 3-566-B (white wrap you see on new cars being shipped) and 3P-224-L (a Plasticied PVC film that has some great traits, but not a strong as the other) were the ones I liked the most, for temporary would work great like for a road trip or keeping the spray of grime off for a car show competition however they are designed for transport and temporary use. 3P-224-L can be made in a clear however they don't get enough requests for clear and is a special order thus clear has a higher minimal order unless enough of us request clear. The problem with using these as stone guard materials is the low tack, with makes it great so you can remove it, but poor for long-term use. I do plan to use these product after the car is done on road trips and things. I see some areas also I'd like to try using 3-P224-L to keep natural scratching down like from the rubber guides for the hood, and rear deck lids. I might haft to see if I can get a higher tack glue for it to work well, but I rather have to week in this than to strong in this case.

Their is one from time to time pops up for sale I was very interested in the car till I got a hold of the flaky owner. Who gave me some strange stories that would contradict what he stated less than 30 seconds before. If I was local at the time I would have looked but to fly out with a shakey background no way. I like your car I think you will have a great project car their. I hope you keep us posted on the restoration.

Just make sure you take all the plugs out before you take it to the shop. My friend is building a Ford 460 to replace the one in his truck and the guy didn't take one out and we used a chisel to remove the rust so we could clean what was missed

I've had the 3 and the 4, the only advantage I found was my three had the dowels witch usually are broken off they seem to help line up the dashpots better, but I could be missing them on my 4 screw carbs. IF your going for accurate restoration change them back, but if it is a car to drive around or race it don't matter.

When you have the head off check to see if you have any warping. Check the valve guides and seats. Unless it was recently replaced look at new timing chain. It will be a great time to replace any worn parts. Also make sure you didn't get any oil/water mixing you don't want that in the engine.

Ok let me assume that you mean inside the cylinder and you found this after you pulled the plug. Then you have a bad head-gasket, and/or cracked or broken water jacket. I'd take that as my clue to take the head off and see what is going on

Do you mean you have coolant in the intake or do you actually mean in the fuel system?

Can he do fuel lines they are similar if the rubber he uses is fuel resistant. I'm thinking of the vent-lines

This is great I'll order a set soon, along with other things like the radiator hoses. What is next, are you going to start making some of the other hoses soon? I'm glad these are done, because they are the hardest ones to replace of the hoses. I'd like to see the vacuum hoses be done next since they are very visually noticeable, especial the line to the brake booster, if your doing more hoses next.

Do a pressure test on the coolant system you should find the leak. They have the tool at Auto Zone for that, in their Loan-A-Tool program. If you can't find the leak with just the pressure test get the special die and do it again. Before you start the test see what your oil level is and see if it goes up after the test. If you can't find it the first time and you used the die don't forget to check the tail pipe for the die. Let us know what you find from this. Trust me one will know if the head-gasket is what is leaking coolant. You will find it in the oil, exhaust, and/or poring out around the head. Don't forget the heater core.

You might not absolutely need a rotisserie. However the car will be easier to work on. Also when welding it's nice to get what your working on in a comfortable position. Nothing like welding while under the car I don't think you will save time, instead you will probably spend more time by trying to get into position working around jacks and other things under the car. Also how long can you work on the hard to get places before your body would get fatigued. I think your going to make a good investment with the rotisserie. I think you will find as you start work on the body without one your going to come to the decision you need one. Just my thought

I'd keep in the hopes of finding the player one day, a little Deep Purple and Black Sabbath would be nice.

OK maybe I should have called it orange or gold, the part that is a part of the vinyl.

Note gurgling is never good. Air in the system can keep the pump from pumping properly or at all. Make the thermostat not open when needed, and reduce or stop flow threw all or some of the engine passages. How well is the fan working, and when did you replace the fan-clutch? Are you lousing fluid? If yes do a pressure test and find the leak, if a bad head-gasket is the problem you will have fluid rushing out in a pressure test. You can't really fix an overheating issue till the leaks are fixed. If your answer is no it's probably not the head-gasket. It would more than likely be a flow issue. Problems can be a bad thermostat, radiator cap, pump, trapped air, blockage or restrictions. What I do is get a new thermostat, and maybe a new radiator cap. Then drain the system and flush the whole system. Detach the hose and blast the radiator out, make sure water flows easily threw it do this to the engine also (if the 81's have a coolant drain plug like the older ones pull it, and flush it out good). Take the old thermostat out fill with water and run it for a wile and drain it, then put the new one in (make sure water is flowing threw the heater core I don't know if 81's had a shut off to the heater core). If that don't work you have a bad water pump, lot of blockage in the engine or the radiator. You can check the pump with a pressure gauge that Auto Zone has as part of the loan a tool program. If that test good, then I look at a new or reconditioning the radiator. If that don't work, new heater core. If that didn't help, I'd be getting ready to pull the freeze plugs and look for blockages, and considering pulling the engine out for recondition as my last option. Be side if you pull the engine out to recondition it you would need to replace those parts anyways. Another thing to check make sure you have good oil flow

It looks like all but the yellow is spot on. I don't know, lighter colors don't always photograph right and yellow is known to fade so it could be right. It is cool that he made color sample to get it right you got what looks to be the right guys on it;)