jonathanrussell

@ensys.... just seeing this. What you wrote above is how I understand it AND it is consistent with what I figured out while rebuilding a 1972 manual transmission D612-53 distributor this past week. For the D612-53, the advance curve is documented in the 1972 FSM on pages EC-12, EC-28, and EC-29. The curves show distributor RPM, not crankshaft RPM so you have to double the number to arrive at the crank advance number. The manual shows an average curve of 12x2=24. When I rebuilt the distributor, I was able to see that the top weight is stamped with the number 12....indicating 24 degrees of mechanical advance at the crank...consistent with the manual. FYI, the technical bulletin manual for Jan 1969 through Dec 1972 has a section that shows advance curves for some of the distributor models that Datsun had produced to date at that time. So if your distributor is an early one you might find it listed in this technical bulletin book starting on page 88. The models listed in the manual for the 240z are D612-52, D613-01, D614-51, and D614-52. In case you have the euro spec distributor, the advance curve works as follows....based on my research and notes (also consistent with my testing using timing light and mityvac). Initial 17 degrees at 650 rpm Mechanical is 6 distributor degrees or 12 crankshaft degrees. Starts at 900 rpm and reaches 12 crank degrees by 2,000 rpm. I haven't rebuilt my euro spec distributor but I would expect the weights to have a 6 (or something close) stamped on the top. Vacuum is 5.5 distributor degrees or 11 crankshaft degrees. Starts at 3.94 inHG and reaches 11 crankshaft degrees by 9.6 inHG.

@madkaw....if you have 72 3 screw carbs where the front bowl lid has longer ears....in my opinion you will never really get the front carb adjusted. What I do now, successfully, is I put a short ear bowl lid on the front carb. Then I use the short needle jets on both. This also helps with the problem of the float hitting the float chamber wall. As Site says....the shape of the float tang is key too. As in his photo above, needs to be curved. The reason...in my opinion...is that the newer needle jets have a very thin needle and they are very sloppy in their movement. They get stuck on a tang that isn't shaped ideally. The original needle jets had much thicker needles and were rounded at the tip so they moved much more easily along the tang. My opinion. I think I read that you picked up a spare set of carbs. Try using the short ear lid on your customer's front carb....get the float tang shape right....and I bet you are money.

@SteveJ ... if you decide to use original rubber for the mustache bar bushings, I have a tool you can use in your press to bend the metal properly into place. If you decide to go with polly, leave the sleeves from the original mustache bar bushings in place. Just burn out / cut out the rubber.

This is great info @SteveJ. Exactly what I have been looking for. Appreciate the video too.

Any chance head is cracked? Give it a try if you are willing to invest time and energy. I am curious whether cylinders seal correctly given the fire / seal rings will have already been crushed. Let us know!

Hi @VaCat33. Sorry about your problem. I have some experience with and thoughts on vapor lock and will share with you. But, in my experience vapor lock doesn't shut the car down for 2 hours. The very worst cases of vapor lock resolve within 30 minutes (in my experience). So, I would at least do some testing on the ignition system. When the car dies, are you getting spark at all plugs? Cap, rotor, points all in good shape? Plugs less than a year old and NGK vs some other brand? As others have mentioned above...is there fuel in the bowls or are they empty for reasons beyond vapor lock? Stuck needle jets? clogged screen where fuel enters the needle jet chamber? Fuel filter? Fuel tank? Vapor lock: I spend summers in Hot Atlanta and vapor lock was at one point a problem with my 72. When I have everything set right, I can idle in traffic as long as necessary and it never vapor locks even on 100 degree days. - I run BP 93 octane gasoline. I need the octane because my E88 head is slightly milled and pinging can be a problem. So, I don't run ethanol free because you can only find it in 89 or 90 around here. I have found ethanol fuel to have a lower boiling point AND....it gets very bad with age. I have found that a tank with fuel much over a month or so old begins to have a lower boiling point...based on my vapor lock observations. I drive my 72 a lot (most days) so keeping fresh fuel in it isn't a problem. When we are out of town for extended periods though I keep the fuel level low so I can fill up with fresh fuel when I return. So, my question is...how old is your fuel? - During summer I disconnect the air intake hose for Winter and attach a different but same diameter hose and run it through the left side round hole in the radiator support. I then keep the summer/winter switch on the air cleaner in the Winter mode. This keeps cooler air coming into the engine. - I use a Mishimoto aluminum radiator and stock fan. Temps never reach 50% mark on gauge. - I wrapped my stock exhaust manifold and carburetor float bowls with a heat shielding product I purchased on Amazon. This lowered my float bowl temps by 20+ degrees. - I run a Carter P4070 electric fuel pump with no manual pump. I also have a fuel pressure regulator set to about 3.5psi and a fuel pressure gauge in line. - My fuel tank has been boiled, acid dipped, and coated on the inside, powder coated on outside so....clean fuel. So, I do believe some if not all of the things above contributed to solving my vapor lock problems. As things stand now, the two things that cause my car to run poorly are.... 1) any hint of fuel that is not completely fresh. 2) spark plugs older than about 8 months. Even though my plugs look perfect, once they are about 8 months old my car starts sputtering around 5k rpms. Change to new plugs and problem gone. I have a petronix electronic ignition in a euro spec 240z distributor fyi. I hope something I have shared is helpful and that you are able to resolve your problem. Take care and let us know what you end up finding to be the problem. J

Lots of ways or combinations of ways to confirm blown head gasket. Smell in the presence of white exhaust.....assuming your sniffer is reliable. Borescope is a great idea. Might be something you can rent from an auto parts store. The leaky cylinder will have part or all of the piston clean. Often the spark plug will be unusually clean too. Leak down and / or compression test can contribute to the evidence. Watching coolant level and seeing that it reduces.

hmm. that could be your clue. eventually that will worsen over time and affect temp. Maybe it worsened a bit when you noticed the change in temp. Will also corrode your cylinders (and clean your piston tops) if the car sits for any amount of time. If you think you have a blown head gasket....I would encourage you to pull the head and fix it. J

might do a compression test. could have a slight head gasket blow / leak. losing any antifreeze? Oil look normal?

Just a couple of ideas to check. Are you sure the throttle linkage is allowing the butterfly valves to fully close? Any chance there is dirt / crud / mice nests restricting the butterfly valves? Not sure I am using the right term...butterfly valves. I am talking about the round brass plates that move 90 degrees and allow air / fuel in to intake. May need to remove carbs and see that the valves fully close. J

Hey @Jughead This is kind of old but I am just now reading it so I thought I would respond. I have never really thought about how I do this in steps but here is my best shot from memory. Also, I assume you are asking about pre-1973 round top carbs. 1) Make sure your nozzles open and close freely. Once verified, fully close the nozzles. 2) Make sure cable wires are straight and not bent / kinked. 3) Move choke lever inside car to off position. 4) feed cable wires through clamp holes on carbs. Don't tighten yet. 5) Tighten base of cable sheath to carb. 6) Tighten cable wire clamps. 7) Test that when you engage choke the nozzles open up. Reach down under the carbs and feel the gap open up as the nozzles move down. 8 Test that when you move the choke off the nozzles close. 9) Hopefully with this done your choke light goes off when you move the choke lever to the off position. 10) Choke should move freely without effort. If this is not the case, something is wrong, kinked, etc.

I use Dorman 96034. Dorman 96034 on Amazon

I had really good results from Redkote. As @siteunseen has mentioned before, it is important to let it cure for a few weeks. I let mine sit for a month. Haven't seen any trace of red in the fuel filters, etc. Here is a summary of what I did. Fyi, my tank was in pretty good shape...not full of rust...more like flash rust where the internal zinc / cad coating had failed. Plug all holes. Use rope to suspend it between two trees...allowing you to rotate the tank while it is filled with whatever cleaner you are using. I also came up with a way to hold the tank still in certain positions. In other words...if I flip the tank in one direction I wanted it to sit in that direction for 20 minutes or whatever. I used muriatic acid first. I used a phosphoric acid after that. At this point, everything looked clean inside. Used alcohol to final clean and evaporate dry. Kind of have to work fast with the Redkote...fill...plug...rotate over and over....make sure fully coated....pour out remaining unused redkote from tank. J

Hey @Av8ferg.... the parts look really great. Do you know if they will work via shipping? Would you mind providing contact info? Also...how much prep did you do before delivering the parts to them?

They are a firm foam but way softer than Poly bump stops.

@JagoBlitz...very interested in knowing how you end up liking the MSA strut mounts. Also...which bump stops do you guys use? Most recently I used the KONI 7034950000 bump stops. They are the best I have tried and will use going forward.

I would just store it, keep the cam lobes oiled, keep cylinders oiled, and rotate it periodically.

Just my opinion but....I think that your numbers matching engine will contribute more value to the selling price of your car (when you sell some day) than it will ever bring by selling it separately.

Excellent video..worth viewing.

Thanks for the info. So, I just stacked all of the parts (strut insulator, spacer, spring seat, bump stop) together....and then installed everything over the koni strut rod sleeve...which is installed at the top of the strut rod. I experimented with both ways to orient the sleeve. The strut insulator gets bolted firmly against the top of the strut rod sleeve we are discussing. The strut rod sleeve slides through the middle of the spacer OR bearing. I So, I don't understand what you mean by your 2nd paragraph above. With everything stacked together, if the wide portion of the koni strut rod sleeve is oriented downward, then it protrudes about 1/4 inch below the bottom of the spring seat. Based on this, I doubt that the 1/4 protrusion would ever damage the bump stop. I do now wonder whether the wide portion of the sleeve, if installed downward, could get hung up in the hole of the spring seat when installed on lowering springs, the car is lifted up, and full droop causes the spring seat to drop below the wide portion of the sleeve. I also compared the parts with KYB and old Bilstein struts I have on hand. Both are the same diameter at the top where the threads end/start as the narrow portion of the Koni sleeve. And, both widen permanently at about the same spot where the wide portion of the Koni sleeve would rest if installed downward. The difference though is that if the wide portion of the koni sleeve is installed downward it kind of serves as something that the spring seat could get hung on as described above. So, for me, in balance, I think I will continue installing koni strut inserts with the wide portion of the sleeve on the top.

I agree that you can install the sleeve either way but I believe that the only right way to install is with the wide section of the sleeve at the top....as shown in the drawing above. FIrst, the wide section of the sleeve gives the strut insulator a more firm surface to rest on. Second, if you install the sleeve with the wide section down, the bump stop could get damaged and it seems like the strut would bottom out against the sleeve instead of the spring perch top. J

Many people would ask why why why anyone would use a n42 head unless you are going to weld and reshape the chamber.

My 240z has the pertronix ignition and coil. I have started using the gap used in the -11 version of the ngk plugs...which is .039 - .043. I experienced what @Mark Maras mentioned above (high RPM stumble) about a month ago and swapping plugs cured it....even though the old plugs looked perfectly good. I broke the golden rule though and changed two things...plugs and plug gap. So, I am not sure whether it was changing the gap or the new plugs that solved the problem. I suspect it was the new plugs. Checking float bowl levels is a good thing to do at some point. There are many ways to do it. I do it the way Mark describes in an earlier post. FYI, it is a tedious process if you need to bend the float tabs to adjust the levels. Can consume several hours...or several days depending on how quickly you get used to how it works. Also, read up about ColorTune. Can be very helpful in getting the mixture right. But...getting the floats right is the first step. Think of it as your macro adjustment and the mixture screw as your micro adjustment. If your float levels are not in the ballpark then you can turn the mixture screw and have nothing happen at all. J

I think your numbers look good.

Welcome. Looks like an awesome car. We might have similar stories. I had a 280z when I was a kid in the early / mid 80's. Ended up selling it when I got serious about college. 20 years later (15 years ago now) I got interested / addicted again. My unsolicited advice is to resist the temptation to take it apart and try to fix / address everything. Stick with weekend or 2 weekend projects and keep it running. This is a great forum. I have learned so much from the smart people who are regulars. In other words, you have come to the right place.