Chickenman

So you're new school learning old Tech.. and I'm old school learning new Tech ?

Digital scales won't help on th springs. On a spring that small, an increase in wire size of .001" to .002" will make a considerable difference in tension. You could use a small tension gauge, or just use the time old method of " sensitive hands " Pull the springs apart with your hands and you should be able to feel the difference in tension. If your hands are not that sensitive or the springs are really close in tension, hook the two springs together by the end and pull. The lighter tension spring will stretch further.

I'll be installing a fully programmable HalTech ECU on my 280Z soon(ish) One of the things I'm really enjoying is the ability to quickly tailor an Ignition Timing curve with 2D and 3D maps. No more muckin' about with hauling Dizzy's in and out, swapping springs, changing weights, filing slots and all that nonsense. Just a few keystrokes and you are done. Plus it is dead nuts accurate... every time.

Can you take a picture of the dizzy cam plate and the slots. One thing I was thinking about is, if the slots are the same length or nearly the same length, then Nissan may not have used a spring with the oblong shape on that particular Model number. Also, if the springs are quite close in tension, the secondary spring may not have or need the oblong end. It's all about how they want to shape the timing curve. Governor weight MASS also comes into play. Nissan used different part numbers with corresponding different Governor weights on different distributors. On GM dizzies, it is very common to switch springs, weights and Cam plates to get the desired curve. All can be mixed and matched and the aftermarket carriers a vast assortment of Cams, weights and springs for GM dizzies ( HEI mainly ) .

Good info, but I need to point out that my question is regarding the springs themselves- and not how they are set. I don't have two different springs in the D612-52 distributor. I will be using your tips to set it up and configure it once it's all together- but I need to know if the springs being the same is a normal thing... Could the ramp-up you described on the Non-Emissions distributors be cancelled out by two same-part springs on the Emissions versions? I am not sure if this is normal. It's never been taken apart prior to doing so myself. In the mean time, I'll see if I can get a photo of it later today. Gotta do some running around! Are you absolutely sure it's never been taken apart in the last 40 years? How are you sure of that? Swapping springs out in the early days was a popular method of changing the curves and often different springs were tried to get the desired curve. . I've even seen BNIB re-manufactured distributors ( and alternators and starters ) thrown together with a mish mash of parts. In the end, it doesn't really matter. You can make either type of spring work to give you the curve you want. Either the heavier weight springs with the oblong end or springs without the oblong ends on the heavy spring. You just try different combo's and check the curve with a dial back timing light or better yet a distributor machine. Check out old timer Drag shops for the distributor machine. I've used Chevy springs in Datsun distributors to tailor the curve to what I want. Of course, the other issue is that Datsun could have used two types of springs. The oblong spring is definitely a stock style spring. I've taken apart many Japanese distributors ( Datsun, Toyota, Honda etc ) and come across that style many times. But that doesn't mean that they didn't make a production change somewhere down the road and switch styles. Maybe someone was in there... maybe not. I wouldn't worry too much about it. Tune the curve to what you want with the springs you have. BTW, you can also buy inexpensive spring tuning kits from Mr Gasket, MSD, Accel etc for Chevies that will fit in Datsun Dizzie's. Buy the early HEI spring kits. It will give you several springs of different tensions to play with, and you can bend the tangs to play with things. Summit or Jegs carry them.

The diagram looks right. The idea is that the lightweight spring is attached to the longer slot, and should pull the weights back all the way to the bottom of the slot at zero rpm so that there is no slop in the system. You bend the tang so that you have enough tension on the spring, so that timing will not start advancing until @ 1,000 RPM At low rpm, the stiffer spring, should be floating free, you notice that it has an oval end that attaches to the tang. Initially, the LW spring controls advance, and it ramps up fairly quickly ( on Non-Emmissions or performace dizzy's ). Once RPM increases more the stiffer spring will actuate, and help slow the advance curve as centrifugal force is really flinging the weights out harder at higher RPM ( over 2,000 to 2,200 RPM Approx. The important thing is too make sure that the LW spring is hooked up to the proper slot and tensioned just enough to pull the weights back all the way to the stop... but also to prevent the weights from advancing till about 1,000 RPM. Some guys set the tension too light, then the ignition timing will bounce around at idle, obviously causing an erratic idle and also losing overall advance. I set my timing at spec ( 700 to 750 rpm ) and check the timing mark with a timing light. Then I lower the idle to @ 500rpm and see if timing drops. If it does, then you have too little tension on the LW spring. Bend the Tang outwards to get a " little " bit more tension. The heavy spring controls how quickly the advance curve reaches full mechanical advance. I usually like it to be " all in " by around 3,500 to 3,700 RPM. You can check. Adjust the tension on the Heavy spring tang to alter this rate. Note: Only tweak the Tangs a small amount at a time. Note: The springs control the rate. The length of the slots controls the total amount of mechanical advance. Plate will be stamped with a number. IE: Stamp 7 = 7 distributor degrees or 14 crankshaft ( Timing mark ) degrees. An " 10" stamp would = 20 crank degrees. Jason Grey has an excellent article on tuning Datsun dizzys: http://newprotest.org/projects/510/jasonGrayDistributor.pl

Glad you got it fixed. That is certainly one to keep an eye on.

The later Hitachi style " emissions " carbs with the square throttle inlets were just terrible, devices. Even in mild climates they were prone to all sorts of issues. The early style " SU's " were dead nuts simple and reliable. We had no issues racing in 90F weather at all, as long as you took the normal SU or carburator precautions. Mind you, oxygenated fuels these days cause a lot of problems. Reid Vapor values are a lot different from what they were in the 70' through early 90's. And that can wreak havoc with any carb in extreme Hot weather.

Yes, Nissan did that with the horrible 1973 and later Square Top carbs, to correct Vapor lock issues as you mentioned. However the OP wanted to return his car to original Series 1 condition, which did not have an auxiliary electric pump. That being said, OP lives in Texas, so there may be some issues depending on ambient temperature ( over 90F ) . A weak mechanical Fuel Pump really aggravates Vapor lock issues.

Always new gaskets. Unless you like doing the job twice...

That's Permatex Ultra Copper RTV...

Stock Nissan gasket for a 77 - 78 head is good. Injection notches won't really affect much. Use Permatex Ultra Copper and lightly coat both sides of Manifold gasket..

That's a nice calculator. Thanks for sharing.

Yes, That is the best way. In fact coating the inside is far superior to coating the outside in heat retention. However, it is much more difficult to do. The headers usually have to brand new as you have to Media blast used parts to get the Ceramic to stick properly. Extremely hard to get the media to clean all the way up the headers, then there is the issue of cleaning all of the media out. Best to talk to the vendor if you want to do something like that. Coating the inside of the header also extends it's life as the tubing heats up a lot less.

It's true. The wrapping dramatically reduces header life, especially on a DD. I've seen the results in person. Headers that literally fall apart after a year of being wrapped due to heat fatigue. Even SS wrapped headers get over heated and turn brittle. Mild steel just falls apart in big chunks. The other problem is that if the car is a DD driver and is run in the rain, you can get sections of the wrap that get soaked with water and road dirt. Usually on the bottom of the collector. On short trips in the rain, the wrap gets soaked in water and doesn't completely dry out. Creates a lovely, corrosive paste solution of water, dirt, etc that just destroys the collector. It's surprising how much water soaks into the wraps. Paint or coating don't have the same issues. Swain Technology is very good. Particularly on the inside of the pipes. A lot of Turbo guys get the inside and outside of the Turbo exhasut housing coated by Swain.

I'm in agreement about keeping the Gun Metal gray for resale. It's a very appealing color and will invite the widest Market.

If your mechanical pump needed a lot of rotations to get fuel flowing there must be something wrong with it. The pump sits at the top of the system and should stay filled with fuel after even months of inactivity. Siphon effect . A few rotations and those float bowls should be filled. A valve can cause the system to take a longer time to build fuel flow. If it's an OEM pump that you can take apart, it may be worthwhile taking it apart. Inspecting it, cleaning and replacing or servicing parts. Sometimes it's just " gunk " on the valve seats. You can still find parts for these if you look hard enough. You can't run the Carter in the system as a helper pump and then turn it off. That will cause a restriction in the line and the mechanical pump's output will drop. You could run it as a secondary pump. It only puts out 4 psi. But then what's the point?

Z cars are fetching big $$$ in BC and Alberta right now. Mainly because we have no survivors from our salted winter roads. Buying has slowed down a lot with the exchange rate, but when it was near Par in 2014, I started seeiing Z cars being brought in on Car Transporters fairly often. Mainly from California and Arizona. My 280Z is an Arizona bought car that lived most of it's life in California.

Well there were a lot of differences in Canadian Market cars and USA market cars, mainly through out the Late 70's through mid-80. We got the expected things like bigger heaters and up-rated alternators. But we also got weather sealed electrical connectors on things like Tail Lamps and other exterior lamps before USA market cars. 720 PU trucks got larger U-Joints in the driveshafts. Different wiper blades. And sometimes we got Euro spec engines with more aggressive cam timing, more compression and a more aggressive ignition timing in the Dizzy or ECU. Edit: Oh yeah. And Daylight running lights. We got those at least 10 years ( 1991 ) before they started to appear on USA cars. In the 1980's, we ran into a lot of electrical wiring issues with Body Shops who started buy cheap wrecks in the USA then rebuild them. They would bitch and complain about the Dealership sending wrong Tail Lamps.... with electrical connectors that wouldn't fit. Shop would have to buy the Tail Lamps from the USA. The PU trucks with different U-joints was a weird one. Ran into that with parts I was shipping into Northern British Columbia. Turns out our Nissan Canada Parts Fiche didn't even show the different USA part numbers.. Figured it out by cross referencing a jobber catalog ( Moog ) . Of course Canadian cars ran into the same problem with things when people traveled to the USA. Became much easier after the early 90's when Nissan started making most of the components to a " Global " standard. But in the early days it kept you on your toes...

You know, We've all heard stories of how they sometimes ran short of parts on the assembly line. Especially in the early 70's. I'm wondering if sometimes they just threw on whatever they had in the the parts bin.

Gotta do something about my insomnia and OCD...

Juts because I'm bored and suffering from insomnia again I decide to do a bit of searching of old pictures. Regarding use of Nyloc's on early Datsun vehicles. The only people it would be really important to ( IE: correct style nuts ) is collectors and Vintage restorers. The Nissan Nylocs were what are referred to as " Tall " Nyloc nuts. I've worked on many, many, Datsuns, Honda's Mazda and other Japanese cars back in the 70's. Rallied and Raced 510's, 1200's and Z's Nyloc nuts were quite common on suspension parts in those days. Not to say that there weren't " crimp " style nuts used on some big bolts as well. FWIW It's hard to find pictures of original 240Z suspensions.. but here's a restoration of a 1968 510 with original suspension. Look carefully and you can see OEM Nyloc's nuts on lower control arm pivot bolt, sway end link bolt and TC rod to lower control arm bolts. You'll have to take my word for it I guess... or not. It's up to you. Edit: I also found a picture of an OEM 510 in an old Datsun book ( circa 1971 ) showing the front suspension components. I'd have to scan it, but this picture also shows the OEM Nissan " Tall " Nyloc on the threaded end of the TC shaft as well as other places. Now, I honestly can't find any pictures of OEM 280Z front suspension, but by then Nissan may have superceded the nuts. But my 9/70 street 240Z that I purchased in 1975 came with Nyloc's on most of the suspension parts, including the big TC rod nut. Same with my 1971 240Z Race car, 1968 510, and 1971 Datsun 1200 . Just sayin' guys... I sold the actual OEM nuts and bolts for these cars... and although I'm now 61, my memory for OEM Parts hasn't faded that bad. All FWIW... peace.

Well, I was actually selling these parts at Datsun Dealerships from 1974 on through 1992, and a LOT of the original nuts were originally Nylocks on the suspension. What they have on them 40 years later in no way reflects what they originally came with. Just saying.... 18 years as a Nissan Partsman at Dealerships counts for something fella's. We stocked a TON of Nissan part numbered Nylocs, back in the early days. For 510's 1200's, Trucks Z' you name it. And mainly for suspension components. Crimp nuts were very rare in those days. However, parts do supercede...especially over 40 years. Nylocks on 240Z OEM suspension? I've seen lots. Have a look at original pictures of sway bar end links, LCA pivot bolt nuts and TC rod to lower control arm bolts. These were all Nyloc's originally. on the early cars. My 9/70 240Z street car had them and so did my 1971 Race car. That being said, by the time the 280Z came out Nissan could have changed the fasteners. ZH. I never meant the original Datsun exhaust manifold nuts were crimp nuts. Poor wording on my part. They never were originally crimp nuts. Just plain nuts as you mentioned. I was referring to the exhaust manifold nuts that Cliff had in his post where we were talking about Jet nuts and the crimp exhaust manifold nuts that he mentioned he got from Nissan. .. it not really that big a deal.

Mickey Mouse POS IMHO. Don't waste your money...

Hmmm... I like that Intake, Is this your own fabrication or did you buy it somewhere. If your own, are you making anymore and how much? TIA. Richard