SU Carb Technical Articles
Various articles and how-to's.
59 topics in this forum
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Seeking the after market throttle shaft like the the one on my 1973z My 1970 shaft is dead in arrival loose cannot sinchro the carbs . I have no clue who offered the fine replacement! It is tight easy adjust . Maybe someone has what they would recommend doing. Using another used shaft.
Last reply by Paul Walt, -
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Last night I replaced the choke (cold start) cables for the carburetors. They need to slide freely and after 44 years of usage and most likely never being lubricated since new, it was time. After doing some research I found that 0.055" Piano wire is the best option for replacement as its affordable and able to push and pull, which is required. I also have more than enough left over and only paid $4.60.After disconnecting the cables from the carbs and pulling the center console apart, I removed the cables from inside the cabin, then measured the length needed. I left myself an extra foot before I cut the Piano wire. I bent it around the mounting plate and then lubed i…
Last reply by SodBuster, -
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In 2015 I cleaned then coated the fuel tank on my 240. Today I put a new screen in the low pressure glass filter that I use. Nothing even close to pink from the Red-Kote, yea for me!
Last reply by jonathanrussell, -
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Swapping some "rebuilt" SU's from a 72 240z into a 71 240z (which has a 72 engine), so I can drive the 71 while rebuilding its carbs on the bench. Pulled off both SU carb pairs. The carbs appear to be all the same, only the intake manifolds and insulators are different. The 72 manifold/insulator combos have two extra holes on the lower edge. The 71 manifold/insulator combos don't have those holes, so the elongated opening in the carb base would seem to be open to the atmosphere. Wondering what the deal is, would rather not have to swap the manifolds as well. Bonus: check out the crap in the last images, both in a carb and in an insulator. Any reason I can't proceed …
Last reply by Captain Obvious, -
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I thought I would share a problem I had that I have never seen before. My 72 240z with 3 screw carbs was running perfectly. With the floats really well adjusted using the 10mm method, the carbs with SM needles run great at about 2.5-2.75 turns down on the mixture screw. With Colortune, idle is a touch rich while 3k rpm is nice and blue. I had been fiddling around with and testing out a lot of little things including fuel pump, some heat shielding around the carb float bowls, fuel pressure gauge, fuel pressure regulator, etc. Suddenly when out on a drive I noticed that the engine was running out of oomph at 4500 rpm. I went on with my other projects but kep…
Last reply by moritz55, -
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For balancing the carbs here are a few quick and dirty methods I use when I don't have a flow meter or WB A/F meter: Setting Idle 0 Assume good plugs, valve adjustment, no vacuum leaks, good fuel pressure and float levels set correctly. 1. Remove air box 2. Warm up car and remove all linkage connections so that the carb's throttle plates are resting on their set screws. 3. Adjust each set screw so that the suction felt when you put your knuckles against the throat of each carb and feel the air flowing between your fingers is the same on both carbs. 4. Stick you head down between both carbs and listen to the intensity of air whistling sound from each carb. It should be t…
Last reply by zKars, -
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Has anybody found an equivalent match to the n27 needle in an SU needle? The n27 needle does not show up in in the SU reference charts. Any help will be greatly appreciated. C
Last reply by moritz55, -
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I have found a NOS Nikki fuel pump in my parts hoard. Still has zinc coating on everything, looks brand new. My question is there any advantage to have this pump over the standard fuel pump? I ask because I am one of the typical people with a built 280 motor and my su carbs seem to starve the engine and lean out on the top end. I have been wanting to add an electric pump but haven’t gotten around to it. And I know there can be many reasons why I’m leaning out, that’s not the discussion please. Sent from my iPhone using Classic Zcar Club mobile
Last reply by AK260, -
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Hi All, 90 days of preparing the 1973 240Z (L28 engine) to breath again, asleep for 17 years. Read all the posts on 3 screw SU have the Ztherapy video as well. With all that said, the car has not cranked over in 17 years, little more complexed then a baseline tune up. Completed the basic fuel mixture setting on the SU's, 2 1/2 turns down. Car backfires out of both carbs. With minor advancements to the setting (richer) the car will progressively start quicker but still backfires (more from the front carb then rear). After an hour of stop, restart, minor adjustments to the carbs the engine now backfires (carbs), stalls and then revs at high rate, repeats the proc…
Last reply by Patcon, -
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Stock Hitachi Needle Valve Assembly: To set the preliminary fuel level, blow in the inlet and rotate the float. Adjust the tab by bending so that the valve shuts (can't blow) when the float beam is parallel to the lid.
Last reply by hatepotholez, -
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Just fitted SU's to my 77 280z. Figure 1. Some notes: 1. The 77 shepherd's hook rod fits the early SU balance tube with no modifications (See Figure 2). The later SU balance tube has the connection point closer to the firewall so the shepherd's hook rod may need to be shortened. 2. The firewall rotation point on the 280z is closer to the drivers side by 21.5mm. For the rod to align properly with the SU manifold, it needs to be moved inboard by 21.5mm (See Figure 3). After carefully using a dowel to find the new rotation point on the firewall and drilling a hole for the bracket, I noticed the bracket has a third hole in the middle. By us…
Last reply by gundee, -
- 2 followers
- 5 replies
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Hi, I’m rebuilding a 1978 280z. I want to swap it to SU dual carbs. Does anyone know of used carbs and all of the other required stuff? Or where I can find them? I can rebuild the carbs if they are in need. Thanks, Andrew
Last reply by madkaw,
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