Guest Anonymous Posted December 25, 2001 Share Posted December 25, 2001 Ok ive been readin about all different kinds of carbureator setups. Ive been hearing the dual SU's are the superior. First of all what the hell are these and how do i get them. Thanks Lance Quote Link to comment Share on other sites More sharing options...
GrayZee Posted December 25, 2001 Share Posted December 25, 2001 Superior? superior to what? if you have a 74 260z and it has the original carbs then it has the "flattop SU's" those are the smog carbs the allow the use of EGR. It has been said that the "round top" (more like a dome) are better. They were found in the 70-72 240Z's There are many choices in fuel systems for a Z however, dual SU's, dual downdraft webbers, triple sidedraft webbers/mikuni's, 4barrel.. If you are mechanically inclined you could even consider taking all the compontents from a later Z (75-83) and convert to fuel injection. Depends what you want and how much money you wanna spend. If you want stock performance then buy some early Z carbs, if you want performance then you could spend a fortune on triple sidedrafts (and your engine would require mods to use them properly) Probably the best (and cheapest) way to get real performance from a Z engine is to get a complete 280zx turbo powertrain and drop that in your car. Or even drop in a big'ole V8! Quote Link to comment Share on other sites More sharing options...
Guest Zpeed Posted December 25, 2001 Share Posted December 25, 2001 I had the early 240z Su's on my car for while, and i belive that they are much better than the later flattops, better response and it feels just a whole lot better but then the Su's started to stuff up on me, they needed a rebuild, or just a big clean, i changed back to the flat tops and regreted it, but when i get some cash happening i'll move back to the round top 240z Su's, i've heard other people saying that the 280zx fuel injection system isn't as good as the 240z SU's HP wise, but i'm not sure, its up to you I've heard other people saying (respected Z mechanic) that they get better milage, HP, response, easier to tune, and are arn't as ugly.. and i beleive all of it, its up to you in the end Quote Link to comment Share on other sites More sharing options...
GrayZee Posted December 25, 2001 Share Posted December 25, 2001 Just thought I would add one more thing, I do know ONE area where the flattop SU's are superior, Ever try and start a early 240z (or a motorcycle) in really cold weather? The roundtop Su's have a choke that uses a sliding jet to richen the mixture, but in really cold weather the engine will not turn fast enough to draw a good vacuum. The flattops have a more conventional style choke (a butterfly valve) They also have accelerator pumps. So the flattops will start easily in the cold. The only way I could ever start my old 240 in the cold was to pour gas right in the carb! Not a easy task for a sidedraft carb! and then you'd have to let it run for 1/2 and hour before you could attempt to drive it. From my experience I would agree that the carbs seem to have a little more "get up and go" but my SU's were a constant PITA they would constantly drift in and out of tune, where my injection system now starts and runs the same... EVERY DAY! I had always dreamed of one day getting a triple sidedraft system, but they are very expensive and now I realalize that for less money you can have more HP with the ZXturbo route. I know that the cold start issue isn't a issue for you at all but I just thought I would throw that in because everyone is always bashing those carbs and I thought I would stick up for them! Quote Link to comment Share on other sites More sharing options...
Guest Zpeed Posted December 26, 2001 Share Posted December 26, 2001 i understand what u mean, i do have some good reliability with the choke setup of the flat tops, thats one plus... how cold was it for you to do that with the petrol into the carb. Does anyone know if the ZX injection system has less power than SU's, i need to rebuild my SU's but thought getting injection will be better for reliability, and will cost around the same. Quote Link to comment Share on other sites More sharing options...
Mike C Posted December 27, 2001 Share Posted December 27, 2001 The early 240 su's work great in most mild applications. I just acquired a set of triple 40 Del'Lortos, so once their goin', I'll let ya' know. I never had problems with my 240 and its original su's in temps as low as 15 deg f. My current 240 chokes are not functioning (console lever pulled out of console plastic) so it is a ROYAL PITA to start. Also warms up slow unlike my last car that warmed up FAST. Heater was warm before I got 2 blocks! Quote Link to comment Share on other sites More sharing options...
GrayZee Posted December 27, 2001 Share Posted December 27, 2001 quote: Originally posted by Zpeed: how cold was it for you to do that with the petrol into the carb. Like I said, I don't think the cold temperature thing is gonna effect almost anyone in this forum. The only members that live in a really cold climates would be some (not all) of the Canadian members and Stoney is from Alaska I think?. My early Su's would require the use of the choke at about 10c and about 5-0c it would be tough to start and colder than that it would get near impossible. I don't drive my Z in the winter here, for starters the salt and sand that they put on the roads for traction causes the cars to rust away, and Z's with very little clearance and not much weight on the drive wheels makes them absolutely USELESS and DANGEROUS to drive on the snow and ice. I did the ole "pour gas in the carb" trick a couple of times just because I had to move the car from point A to point B but I would guess that it was -20c or colder when I did that. I don't imagine that you see temps like that in Austrailia though! B.T.W. need a house guest from Dec to Mar? Quote Link to comment Share on other sites More sharing options...
GrayZee Posted December 31, 2001 Share Posted December 31, 2001 The temp gauge would be up and the engine would be warm with good heat before it would run properly (probably because the carbs and carb heater hoses are too small and have lots of surface area to dissipate any heat) especially in -20 or colder. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 31, 2001 Share Posted December 31, 2001 possibly your thermostat is partially open. This will cause slow or no warm up in the cold weather. Quote Link to comment Share on other sites More sharing options...
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