emptech

I'm getting very close, one carb at a time. One photo is the view looking down the nozzle, which has been set to 10 turns. Once there is fuel, I can shine a flashlight down the hole and see the level, I'm usually either too high or too low, trying to find that sweet spot. The other photo is the rear float, you can see the weight that was added so when the bowl is at the proper level, the float is level, not canted, where it would hit the ceiling of the bowl. There has been a lot of discussion on that in this thread. One of the photos shows the weights that were fabricated. BTW, although the carbs are from a 240z, they are being installed on a 260z, getting rid of the flat tops. Jim emptech@surewest.net

Mark: I can't tell you how many hours I've spent on these carbs. I bought them used and had no idea how much the person I bought them from messed with them. I've spent many hours trying to get the fuel to the proper level in the bowls. I purchased some sight glasses from Z Therophy so I can actually see the level in the bowls, but I've found that is a waste of time. The best way I've decided is turning the nuts down 10 turns, 10 mm. Taking the domes off and letting the fuel pump fill the bowls, take a look down into the nozzles. I think I'm still about 2mm low, don't know how critical that is. I cannot start the engine. I can start it on ether but can't keep it running, I think it is still too lean. I need to get back to the float adjustment again. If you have been following this thread, I added I believe 6 grams of weight to each float, so when at the proper level, the floats are level, not pressing against the tops. Again, I'll report back. Jim

I decided to go through all 14 pages of this thread. I spent many hours trying to get my fuel level in the bowl correct, whatever "correct" is. I even fabricated a plexiglass model of the fuel bowl so I could actually test the float in combination with the needle valves, which I know are NOT grose valves. I also found I was totally wasting my time by measuring the distance from the top lid of the fuel bowl to the top of the float, which we now believe was meant for grose valves. The critical measurement I've learned is the actual fuel level in the nozzle, not the bowl. Either .426" or 10mm would be the level of fuel below the carburetor bridge. That level happens to be based on the fuel level in the bowl, which is determined by how one bends the tabs on the float itself. Some of us have discovered that to get the proper fuel level, the float is actually too high in the bowl and is dangerously approaching the lid of the float bowl. As you can see, CO has fabricated some brass screws that when inserted into the float will help the float attain the proper angle when the fuel level is correct. I have fabricated similar screws and will drill and tap holes in the float as CO did, and hopefully after re-adjusting the tabs will finally have the proper level. I will report back with my findings, but from I've read from CO, I am expecting good results. Jim

CO, I see the last message in this thread is from Sept 2024. I've spent many,many hours trying to get the float set properly, I've had the same problems all others have had. I've bent the tabs many times and have hit their limits. I'm convinced that adding ballast weight to the floats seems like the best idea. I like the idea of using a brass screw, either off the shelf or fabricated. I have a lathe, so I can fabricate the screws. What did the screws end up weighing? On a '74 260Z I am pulling the flat top carbs and replacing them with 240z carbs. The ears are one long and one short, so appears they came from a 71-72Z. I hope to hear from others - Jim Sacramento, CA. emptech@surewest.net

I couldn't help notice that you were measuring 23mm below the top edge of the bowl. According to the factory manual, the 23mm starts from the bottom of the float bowl lid. Turns out the distance from the bottom of the float bowl lid to the bottom of the lid is exactly 3mm, if you don't count the thickness of the gasket, the proper level for the fuel would then be 20mm below the top edge of the bowl. Nobody has ever said how accurate this has to be, but we know if the level is too high, we get a rich mixture. I re-read your comment, I measured 3.0mm, you measured 3.4mm, close enough. It's so much easier to just measure 20mm down from the edge, why is everybody stuck on 23mm? Jim

Mike: I know you got it fixed, but it seems like a fusible link from your description. Has four pins, if you take the cover off you probably found two wires, each one like an inverted U. One was probably fried. What is more important, what was the cause of the link blowing? A fusible link is nothing more than a piece of wire of a specific gage that gets hot when there is too much current and it burns open, nothing more than a fuse in effect. Jim

You answered the above questions. Don't worry about the battery voltage, seems to be cranking just fine. It isn't firing, either a fuel problem or an ignition problem. Might be easier to check ignition first. Pull one of the spark plugs, attach the ignition wire to the plug, lay the plug down on the engine somewhere, like on the intake manifold. Make sure the metal part (threaded) touches part of the engine. Crank the engine, if you aren't at a good angle, have somebody else crank the engine. You should see a spark appearing at the gap. If you don't, you have an ignition problem. If that's the case, you have to work backwards. Pop the distributor cap off, crank the engine, see if the rotor is turning. We can give you more items to check with. If you wanted to test for a fuel problem, you could squirt some starting fluid (ether) down the air intake, after removing the hose to the filter. I don't have a 280, so can't describe it. Try cranking the engine, if it pops, tries to start, could be a fuel problem. From there, clogged fuel filter, fuel pump problems, clogged fuel lines, empty gas tank, on and on. Hope this helps. Jim

On one of my older engines, my chain tensioner stuck out like that, it was because I had so much milled of the head, the chain got loose. So that the tensioner wouldn't pop out, I machined an extension for it, ran for years, not because of worn chain guides. I cooked the engine one time, warped the head real bad, had to shave both surfaces of the head, decreasing the distance between the two sprockets. Don't recall from the thread, did you have the head shaved? Eventually I bought a new head and all dimensions came back to normal and I was able to go back to the proper tensioner. Of course, a stretched chain would do that too. If I recall, it is pretty much a straight shot from the lower sprocket to the cam sprocket on the "pulling" side, whereas the tensioner simply takes up slack. Would seem to me that a lot of the plastic would have to be missing to cause such a problem. Jim

There are two places where three sets of bearings go. The last one is in the spring held by a clip. It is the location closes to the mounting plate that holds the pickups. There is a plastic three fingered item that holds the balls. It goes between two metal plates. I'm trying to figure the orientation of the plastic item and the two metal plates, such that as the advance plate goes through it's several degrees of motion, the balls stay in constant contact with the plates. When it came apart, the various plates got rotated. I don't think anything got flipped over. I'll eventually figure it out. I can't tell by any "tell-tale" marks from where the bearings were because the surfaces were all rusty, and once I cleaned them with sand paper and scotchbrite, the marks from the bearings went away. With time, I'll figure it out, but would be nice to see a blow up. Jim

I'm in the process of repairing a 260z distributor and found it was all rusted up, all stuck together. Now that I got it apart and cleaned up, although I was very careful on how I laid the parts out, I'm not sure how the parts having to do with the advance plate mechanism line up. I've had to replace all six ball bearings and don't see how the plates line up that sandwich the bearings. The factory manual doesn't show these details. I found a tutorial on a 280z distributor, but the parts don't match the 260z. I have a 240z distributor but it's parts don't match either. Not that it matters, this distributor has two pick-up coils. Not an emergency, but it is the only thing stopping me from firing this baby up. Thanks in advance - Jim

What is a coolant cap? I know what a freeze plug is. I had to modify the coolant system on a 260z I'm converting to round tops, had to plug some of the metal lines. I machined a brass plug and silver soldered it into the holes in the tube. I could have left a small piece of hose with a bolt as you did but wanted to do the job right. That way the lines still look original, they just have a blunt end where the hose used to go. Jim

To determine if it is the switch, pull the wire from the connector, if the light goes out, bingo. I've heard they don't always reset, but your mileage may vary. Jim

Kind of late on this one but nobody has mentioned the proportioning switch. The proportioning switch is under the hood, most obvious because it has lots of brake lines going to and from. There is a wire attached to the middle of the switch. It triggers by a differential of pressure between the front brake system and the rear, when the piston travels from the middle position, it turns on your brake warning light, same as the handbrake light. To test for this, pull the wire from the switch, if the light goes out, that's the problem. If the brake pressure problem has been fixed, the switch will either have to be manually reset or replaced. Jim

Speaking of using a bench scope ( I have several, all tek) for automotive use, I would loosely couple to the hot wire right off the coil. Loosely means a few turns of hookup wire around the high tension wire, the end to the scope probe, just creating a small capacitor. The trigger of the scope couples to plug #1. Given the proper sweep rate for the rpm range, you can see a representation of the waveforms for all plugs, the distributor being your multiplexer. The order would be the firing order of course. I suppose if you wanted to get fancy, you could put a second channel on the trigger from your points or pickup. Jim

John: You are right about the higher compression ratio, that's mainly why alcohol is used in indy cars, but they are using methanol. I worked 32 years on the circuits, did fire/rescue. I worked in the pits along with all of the big boys. The indy people also claimed it was safer than gasoline, probably true, but you couldn't see the flames. You saw drivers dancing on the ground, paint wrinkling, shadows of the heat waves, grass burning, clothing starting to burn, etc. but the good thing, plain ole water put it out and cooled too. Also, what is fuel drier? Nothing more than alcohol, since it has an affinity for water. Here on the left coast there is no source for ethanol. It all comes from the midwest, shipped out in tanker cars, then blended locally with gasoline to produce e85. There was a facility in Stockton, CA that processed ethanol but it closed down. Don't want to get political here, but e85 is a scam, I went back to gasoline. I bought some regular a couple days ago for a discounted price of $4.65 a gallon, and I remember gas wars years ago of less than 24 cents a gallon. Jim