Carburetor Central
If you have questions about the SU Carburetors, this is where you can find the answers.
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I’m having a high idle speed issue. I’m running between 1,600 and 2,100 rpm. Prior to this, my 74z with a modified 280z engine running a pair of SU’s was having starting problems and would sometimes stall and idle somewhat slow. I decided to try and adjust the carb’s using https://zcarguide.com/tuning-adjusting-datsun-240z-su-carburetors/ Because one of the fist things to do was to check the spark plug condition and gap, I installed a new set of plugs. I’ve never adjusted the timing because I cannot find the timing mark (I have a gun and I know how to use it). I set the idle screws all the way out and then backed them in 1 ½ turns. Then it started right up wit…
Last reply by Jeff Berk, -
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Hey guys so after trying to get my 260z with Weber 32/36 carbs set up(which I just rebuilt) I finally got it running today! It’s not running too good though haha. When I started it up it was idling at about 5k rpm! I tightened the idle mixture screws a bit and got it down to 3k rpm, obviously better but still really high. Another strange thing is when I turn off the car, it almost keeps running but dies slowly and starts blowing some white smoke from the top of the carbs. If I want to kill it right away as soon as I turn it off, I floor it to open the throttle valves and it shuts down smoothly. A couple things that I think may be causing these issues and wanted …
Last reply by Racer X, -
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So I have a stock engine in my 1974 260z with SU carbs from a 1971 240z. Is there really a significant performance difference by switching to Weber carbs and is there and difference between the Weber dual carb set up versus the triple carb set up? I'm trying to decide if it's really worth the money to change.
Last reply by Diseazd, -
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Need one to get my 40 PHH's tuned. Anybody know somebody?
Last reply by dutchzcarguy, -
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Getting ready to source a set of carb's for my neighbors series 1 restoration. Motor is rebuilt & car almost ready to be dropped in. No carb's came with the car. The options are : buy a set of 4 screw carbs and send them off to be rebuilt. Or.... buy this new set from Round Top Fuel Systems. https://roundtopsfuelsystems.com/new-products/original-round-top-carburetor-set The cost is close to the same, say $200 for the core carbs plus about $750 with shipping for the rebuilts vs $980 for the new Round Top Su's. What say you? The Z Therapy route is a well known proven product. Has anyone here purchased the Round Top Fuel Systems carbs? …
Last reply by AK260, -
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I bought a set of K&N filters to install on my round tops. I know I’ll see no performance gain or gain any credits amongst the purists but I just kinda like the way they look, along with the valve cover breather. I’m keeping all the original parts in a box when/if I want them in the future. My question is what do I do with the float bowl overflow lines that are routed into the factory breather box? Thanks
Last reply by Stanley, -
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Hey guys, hope you’re enjoying your Sunday, I’m spending it trying to rebuild the carbs on a 260z that’s been sitting for years. I’m almost done putting everything back together! New plugs, fluids, belt, hoses, my final step is rebuilding the carbs. I took them all apart last night and saw something very weird going on regarding the choke shaft and plates. On one of the carbs, there was no shaft or plates and the holes for the shaft were closed off. On the other one, there was a shaft and no plates. I’m new to carbs but I know this doesn’t make sense, how is the air ratio being controlled if there’s nothing stopping it from entering? I know someone had messed with these t…
Last reply by bravemushi260z, -
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Hello gang! My new bad obsession this year is the inlet side! Beyond planning on a new CAI and some David Vizaardry on the carbs, I have a new unhealthy obsession with inlet tract tuning. I have read many references to this not on a Z car, but I am keen to hear from you good fellas as to what we know of, that has been experimented with on a Z. For example, I regularly hear that the stock trumpets are actually very good. But what does that mean? They are no doubt very good for stock engines / cams / exhaust combo etc but what about modified engines with more overlap and duration? It’s common knowledge that long stacks give you better mid range and short on…
Last reply by AK260, -
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For the past several years, I've chased a random fuel starvation issue. My 73 with round tops would randomly sputter and die. It might happen when barely warmed up, or when ran for a long time. It might happen after being driven for a while and then parked for a bit and then restarted. It would happen under load or not under load. Heck, it died while coasting down a long hill. Ambient temperature didn't matter. Would happen on a cold day after barely warming up. Just totally random. Always eventually restarted after several cranks and then might run fine, might randomly do it again. I tried replacing the filter, then the mechanical fuel pump (no electric). I dro…
Last reply by dutchzcarguy, -
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I am helping my retired neighbor with his project which is now in the assembly stage and rounding up some of the missing parts. The car is a 1/71 build date. Vin is 19270. His goal is to keep it all stock. Are the correct carbs the 3 screw or 4 screw version? I don't know how early the transition was.
Last reply by Namerow, -
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I just got word my Z therapy carbs are on the way. There is a $200 core charge. My old carbs round tops, arent bad. Are they worth more than 200? would you keep them, get the core refund or sell on Ebay
Last reply by grannyknot, -
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Hey guys I am so excited to be buying my first z, I've always loved these cars and wanted to start a project car. This a 74 260z that has been sitting for about 5 years, I read Carl Beck's guide on how to get this car running, and my plan is to check the tank, change all fuel lines, change all fluids, and replace any hoses and belts, and clean up the carbs. To be completely honest with you I have never worked on a car this old or on carbs before. I am trying to identify if it has the flat tops or the SUs from the earlier zs. I dont think it's stock but if you guys could help me out with what is changed I would really appreciate it. I can't find any photos of just a stock …
Last reply by siteunseen,
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