metalmonkey47

Thanks guys! I feel a lot more confident about doing this now. Cheers!

Getting ready to pull the mustache bar possibly tomorrow to do the bushings. Is there anything I need to know before doing this? Do I need to support the diff in any special way? Or is it pretty much as easy as just pulling the two bolts on the diff, and the two on the body? Also planning on drilling the bushings and cutting the remainder of the rubber out of the bar. Is there any easier/more time efficient way to do it? Or is it about as simple as it sounds?

Not surprised Eric. Hope that solves your problem!

Yakhopper, I purchased them from a member on here. They are Bendix # 66673, but all the large seals were stamped Tokico Japan. They are still availible on Ebay and on Rock Auto. Seems like a great quality seal too. Turns out after doing some research, they're 280Z rebuild kits. All of the seals are the same, except the backing plate dust boot. Edit: RAYBESTOS Part # WK816

Don't be so modest

Nevermind, figured it out! My kit was incorrect, although like I figured the only change was the dust cover for the backing plate. The rest went in just fine. Happy to say there was no pitting in the bores whatsoever so it went together just fine and doesn't leak. I'll share some before/after pictures for the photo junkies here.

I'm assuming the FPR is the issue. It's black on all 6. Again. I have a Holly 1-4 PSI regulator that I just picked up yesterday, but I've got to find the proper fittings to match my fuel lines on the car. Thanks Steve, I think I'm busy all weekend (like most) I might have to try and catch up with you soon. Still don't have working turn signals ::

Well like flipping a freakin switch, it started running pig rich today. No reason whatsoever that I can find. I started it up to pull it in the driveway, finished rebuilding the wheel cylinders, started it up to move it out and test the brakes. It's running so rich it's missing like crazy. Plugs went from clean/tan to black in a matter of minutes. This car is testing my sanity.

Had a similar issues on my L20B. Since neither hole is through the timing cover, I just drilled/tapped and used a HeliCoil. Never had an issue again.

Also this is my kit. Assuming from top to bottom is: 1. Dust boot for the backing plate. 2. Bleeder cap 3. Piston dustboot 4. Main piston seal

Hey guys, so getting winter down south here, and I've decided the brakes should be my main focus on my Z before the weather turns to crap. My brakes haven't been the 'best' since driving the car. I find that unless I pull the parking brake lever up a notch or two, the brakes seem to be really weak. I've already replaced the front calipers with remans, replaced the master with a BRAND NEW (non reman) 7/8's master, and now I'm getting to the rear brakes. The wheel cylinders are leaking slightly so i figure that's where my issue lies. At this point I suppose it makes sense to mention I've already adjusted the rear brakes tight. Anyways, I did some research and found that there seem to be a change in the wheel cylinders halfway through the 240's production and I just want to clear a few things up before I go ahead and rebuild the wheel cylinders. I bought two bendix rebuild kits (parts stamped Tokico Japan) but was not aware of the difference. Although it seems minor and something to do with the backing plate/brake line angle or something that I don't recall 100%, can anyone confirm that the bore size is the same, and the seals/dust boots didn't change? I really don't want to take this apart before making sure I have the right parts. Also, is it worth honing the bores on the wheel cylinders during rebuild?

Sorry guys, I don't mean to be confusing, I might be using some confusing terminology. It has unknown needles in the suction pistons. There's no markings at all on the top, likely worn away with the numerous times they've been touched while I try to get this right. Anyways, I'm gonna side track for a second. HUGE thanks to Blue! Turns out, he was right around the corner all along and stopped by a few nights ago to lend a hand and help me learn a bit. We took the carbs apart on the car to check out a few things, and to teach me a little about how they function so I can better understand how to track down my issues. Turns out, I did have a few issues to be sorted. We didn't bother to mess with the floats because it seems that the primary issue lies in the nozzle on the rear carb. When doing the drop test to set the needle height on the rear carb, we saw that the needle was sitting 1-2mm below the deck.with the nozzle full up. Turns out the nozzle at full up STILL sits about 1-2mm lower then the front. The nozzle also looks misaligned. I had issues with that from the beginning and thought I fixed that, however while it fixed the piston hanging up (months ago, just after buying the car) it is still not 100%. I'll be reading into Blue's thread on that simple fix-it and going at it soon. Probably also going to look into new proper needle/seat's for the float's. I'm still very sure that they are leaking. The plugs look way better after doing some fine tuning with Blue help, and it's not nearly as rich and runs much better....but occasionally I get raw fuel smell in the exhaust and I believe the rear carb may be flooding over into the venturi slightly.

Possibly so the gaskets/instructions all matched 240Z can had different float adjustment specs for '70 and '71-'72 so I suppose it's possible the company made a 'one size fits all' and the needle valves are incorrect for my year carbs. It's good to hear that I'm not the only one that's had that happen, because I'm about 90% sure that's where my issue lies. I don't know if I ever mentioned, but for the record, the carbs (in fact, the car itself) is pretty much ALL bone stock. The PO said for the time he had it he never had anyone touch the carbs. I recall years ago he came in with fuel spitting from the carb vent, and knew I was a Datsun guy. I pulled up a diagram of the SU's having never looked at one before, and we popped the bowl off and fixed the sticking needle valve in the parking lot of my store. We fixed a few problems now and then... that's actually how I ended up getting first dibs on the car when he decided he couldn't afford to fix it, and sold it to me for $1000. I figured as much about the floats. I've been on the lookout, and fortunately quite a locals have spare carb parts laying around so if anything broke, I'd only be out a couple bucks. Madkaw, that's a good possibility. There is a VERY slight difference in length between the 1.7 and 2.0 needle valves. Probably just enough to really throw off my mixtures. I do have the old ones, but they leaked so bad before, it's hard to tell when re-installing them if they're flooding from a separate issue...or because they're simply worn out. The needle tang seems to be pretty smooth, I've finely watched the operation under a magnifying glass and don't physically see anything hanging up. Sorry I believe in all of the confusion I may have missed it. The washers between the float cover and the needle are all in place and snug. I took a spare washer and tried shimming it down a hair but it made no difference. Well that's convenient PM incoming!

For the record, this is the car, and it is WAY too clean to be running this bad :: Seems like out of all the datsun's I've owned, the dirtiest looking ones ran the best.

Thanks guys, glad I'm back on track again. The car just started running EVEN richer now, so I'm a little annoyed. It was so bad I had to look for my exhaust leaks today and fix them :: Guess it wasn't hard since the pipe was literally cover in black soot around the leak. I've tinkered with the floats again and again but it seems that no matter what I do, I can't get them right. I've had the floats set literally so high that 2.5psi took forever to fill the bowls and it ran super lean. Just a hair lower and it floods. Which is strange because they seal, and the floats aren't leaking. I've played around for about 3 hours in 35 degree weather just trying to find the sweet spot. But part of me things the issue relies in cheap needle valves. The tangs on the floats probably won't survive many more adjustments. The old needle valves spray gas so putting them back in is useless. I had to replace them after getting the car because It was pouring gas out of the throat onto the exhaust. Dangerous. I think at this point I'm going to start by ordering a few gaskets, new floats and new needle valves from Z Therapy next week and take a few days off of work to pull the carbs and reset everything. The issue is getting progressively worse now and the car is running very inconsistent. But I guess you could say that 'out-of-whack' carbs is a good assessment. They're sync'd perfectly, but fuel wise........well you can see what I'm dealing with. Stanley, thanks for the suggestion! I didn't even consider that. Gonna give it a go and see exactly where my floats are shutting tomorrow. Although I don't have a choice, since the car is running poorly under load. Getting backfiring when accelerating. Probably due to excess fuel.

Sorry I'm not familiar with the flat top-round top years. They are '72 rebuild kits. According to some basic research when I needed to buy the kits, they were supposed to all be the same from 70-72. In fact the carb kits list float specs for '70, and '71-72. I may be a little vague back there, let me try and back pedal and try and make sense of it. I used a clear hose to measure the fuel level in the bowls. Apparently 23mm down from the top of the bowl is the correct fuel level. I made some adjustments to the float, trying to get the level down to 23mm but regardless where I set the float, the level in the bowl always returned to 13mm from the top. I left it for the night and wnted to come back to it today with a clear mind. Today I pulled the domes and pistons and found that the front carb was flooding over the nozzle tip. The rear actually seemed to be settling a little low so I focused my attention on the front carb. Same issue fought the night before. Regardless of float height the fuel level in the bowl was always too high and flooded the nozzle tip. I swapped the float from front to rear and the problem did not follow, so I swapped the needle and seat and noticed the rear carb now reading high. I ought to mention, when I say it's flooding, i don't mean that it's spilling out of the float bowl vents, the fuel level just rises to the top of the nozzle and occasionally dribbles over the nozzle. This has been a progressive issue from the beginning. It's been very inconsistent up until now. Now it would appear the needle and seat would be the culprits. They do seem to seal which is strange. I hooked em up to a zero loss air pump to measure the point where pressure overwhelms the valve/float, and they don't seem to leak at all. I also flipped the cover over and let gravity hold the float to the needle tip, and at 2.5psi-3psi there is no leakage. I pulled both needle & seat assemblies and compared them to the old ones and found that the new ones have 1.7 marked on the side of the body, and the old ones are marked 2.0. Disassembled I don't see any major differences in the assemblies, although the tapered tip does seem to be slightly different.... Any idea what those marking refer to?

Alright, so here's what I've found: I used a clear hose and the nice little measuring tool that came with both rebuild kits for the carbies. (I ordered it for a '73 from oriellys because they didn't list a '70. I'm assuming both year 4 bolt SU's use the same float) The level in BOTH carbs was about 10mm too high. I adjusted both floats starting with the rear carb and found that BOTH seemed to still hold the same amount of fuel as before. in fact, regardless how low I set the floats, they seem to both sit about the same height as before the adjustments. I pulled both floats and layed them in a bowl of water, they're both buoyant. Holding them below water neither seems to leak and I see no bubbles. I blew some gunk out of the return line, which seems to be operating perfectly. I verified I'm still getting 2.5PSI to both carbs Now I'm just about as annoyed as ever. I cannot seem to decide what's malfunctioning or what I might be doing wrong. Needle & Seat - Sealing fine Float - Floating/Not leaking/Not hanging up Fuel Pressure - 2.5PSI Fuel Return - Free & Clear. So what's the next step?

Sorry guys I've been trying to find time to tinker with it. 50 hours a week at work is not Z car friendly. Anyways, in the video it was running on JUST the rear carb. I took some time to pull the nozzles and inspect them, and they look just fine so I swapped the nozzles from carb to carb to see if the problem followed. Didn't seem to. My fuel pressure gauge that i WAS using was far from accurate. It read a lot higher then reality. I have a new gauge (designed for EFI levels but still accurate at low psi) and it seems that the regulator is working just fine. When I was tinkering around with fuel PSI I was looking for regulator output pressure with the engine running to see if it varied at a higher voltage , which it did not. I pulled the pump fuse for one reason or another and noticed after about 30-40 seconds the idle stabilized and the car seemed to run better and didn't smell even a lick rich. I let it run until one carb finally shut off, killed the motor, and found that the rear carb (the one that was still running the car with the nozzles turned up) had emptied a slight bit quicker then the front. The fuel level in the bowls is identical when they're full. I'm assuming that my issues seem to be float level related. I'm gonna grab a clear hose and see if I can re-check that to make sure nothing changed.

Problem #1... I hooked up a fuel pressure gauge and found that with my regulator set to 2.5 PSI, I was getting double that at 5psi. Had to bottom it out to .5PSI on the regulator to get 2.5. I reset the height on the floats, and the needle/seat are NOT leaking at all. In fact a detail I think I left out is that they are brand new. Anyways, everything I did is hard to put into detail in one post so I made you guys a video, hoping maybe you'll catch something I don't. To be hones though, I'm about 90% sure at this point that the nozzles are going to be my issue. Bruce, I'll probably be giving you a call in the AM. http://youtu.be/jXMM4uWU5dY

Well to a degree I'm sure it displaces a little fuel in the nozzle, maybe not as much as I think. Probably not my issue now that I think about it. My pump is installed at the fuel rail level with the pick up tube in the tank, and I have a regulator installed post filter set to 3 PSI. I have no gauge installed to verify at the moment, but I guess I'll have to put one in tomorrow. I happen to have one laying around if I can find it. I have no idea what the fuel pressure does when the engine is off, but I'm sure it's not dropping off. Now that I think about it, I've had a few times where I've pulled the float bowl cover and has fuel spurt from the needle and seat. The only time I've looked was the other day, when I pulled the pistons/needles before starting the car to try and diagnose the hard start condition. That's when i notice raw fuel settled in the venturi. I'm curious if it's spilling over into the intake manifold as well. The car is running terribly rich on both carbs, I've never had an issue with it rubbing or binding in the nozzle, but I can't speak well for the PO.... he was a bit of a tard and never touched the carbs so there's a chance that he never touched them in the 15 years he owned the car. When I disassembled and cleaned the carbs off of the car, the nozzles and needles were in awesome shape with no visible corrosion. They both drop fine with no binding. I've gotta change the exhaust flange gasket tomorrow morning before doing any carb work (gotta get some of that rich exhaust away from the cab) and I'll reset the needles and get a fuel pressure gauge in place. This is annoying.

I wouldn't say it was 'high' I didn't even measure it to be honest. I measured it by the level of fuel in the nozzle. I suppose I need to pull the bowl cover off and hold the needle and seat closed together and see if they seep with the fuel pump on. I ran the fuel pump with the pistons out and didn't see the fuel level in the nozzle change even the slightest so I guess that's a decent indication that they aren't leaking.

So I took the time to pull the needles and pistons today to look at my float levels, and I found that I'm having fuel puddle in the carb venturi's with the engine not running. Looks like when the pistons drop, they're splashing fuel into the venturi's causing the hard starts/uber richness. I got 115 miles to the last tank. That's terrible. I lowered the front carb a tad, now I just need to lower the float in the rear carb tomorrow and hopefully I'll be able to get my mixture dialed in better.

We actually had a pretty productive discussion on one of the Facebook pages last night (I think it was Datsun Parts and Needs) about overheating issues around the last two cylinders cause by bypassing the heater and feeding hot coolant back to the rear of the head. Apparently someone has measured the rear of the cylinder head at about 220 degrees under a 50hp (or so) load at somewhere around 3000rpm and 170 at the front with the heater bypassed straight to the rear of the head. I'd love to find those links again to reference.

That tells you right there that there's a 90% chance the core is the issue. If the valve or hoses were leaking, it wouldn't get onto the core, meaning you wouldn't be fogging windows as you drive and blowing moist air through the vents. it's possible the core corroded around the leak from seeping, and it's just a ticking time bomb. I had the exact same issue in my 620. I took it apart and found it leaking everywhere. Ended up un soldering the tanks and it was a mess. I couldn't get it soldered back together because it had a 2 piece tank, so I took it to a radiator shop and paid them $60 to soak the core/tank in solvent, and re-solder it. The results were good. _DSC0074 by metalmonkey47, on Flickr

Sounds like that's where my issue is then. My float levels leave the fuel in the nozzle right at the tip, so I bet it's flooding over with the piston down. I'll lower the float a tad and see what it does.