Initial Z Posted March 16, 2006 Share Posted March 16, 2006 Ok so I have a 73 240z that I just got and have been taking apart for body work and paint eventually I’m going to get a SR20DET in it but I want to get it back in driving condition until I have save up enough money. The main problem is the clutch is smoked and the engine is pretty tired and its got the bad carburetors from that year. The engine dose run but it burns oil until it worms up (the exhaust is a thick gray blue smoke when its started cold). I don't notice any strange sounds while its running but the oil pressure gage doesn't move much. It did have a tune up not to long ago so its probably about as good as its going to get with out new carburetors or a rebuild. Im kinda thinking about swapping out the engine for one with less milage and better carburetors possibly something from a 260z, 280z or zx. Do those engines use all the same mounts and whirring? Or should I rebuild the one I have, but then what to do about the cabs? Basically I’m looking for the cheapest way to a reliable engine, what do you guys think? Thanks, Nate Quote Link to comment Share on other sites More sharing options...
AK-Z Posted March 17, 2006 Share Posted March 17, 2006 Actually the 240z su round top carbs can go for a pretty penny. I suggest you rebuild the carbs, and a oil change if you haven't already. See if the head bolts need to be retorque. Wiring is totally different between the 240z and 280z if you want to go EFI. the L26 uses carbs but is bogged down with emissions crap. If you do want to do an engine swap with a L6, then I suggest you get a L28 non turbo engine and take off all the EFI stuff (basically all the stuff mounted on the intake manifold) and mount the carbs on there. Quote Link to comment Share on other sites More sharing options...
Initial Z Posted March 17, 2006 Author Share Posted March 17, 2006 So are the round top carbs realy not that bad? Why dose everyone say they suck? And, where can I get a rebild kit for them? If I keep the engine I have, should I be conserned with it smoking when I start it cold? Isn't that a sine that the piston rings are worn out? Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted March 17, 2006 Share Posted March 17, 2006 Yeah what he said! Make sure you have the good SU's "round tops" If your damper housings are flat top then you have the boat anchors. In the 240's as far as I know they only came with round tops and those are GREAT, as far as carbs for L engines go. You never know with Nissan they mixed all kinds of stuff around at the end of a year model i.e. hatch glass with vertical vs. horizontal heater lines. As far as how to refresh your L24 ... well it depends on how far you want to go and how much you want to spend. AK-Z was right if you wanna great, easy, cheep, temporary engine, get an L28 short block from a junk yard and while you have the head off (if you take it off to put the e-88 head on the L28 short block) just replace the valve stem seals and poof. You should have a great running engine for a few hundred bucks. Like I said ... depends on how far you wanna go with the temp engine. Or... scrap the RB build and get an N42 short block with a maxima diesel crank, use your L24 coneting rods, KA24 pistons, P90 head, 2mm HKS head gasket, non-egr L28 intake manifold, 420cc supra injectors and custom fuel rail, megga squirt engine managment, T3/T04 hybrid turbo, bitch'n exaust, and a few other things and BOOM! 350 rear wheel horse power... I know the RB's make more power but... Its up to you! Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted March 17, 2006 Share Posted March 17, 2006 round top or flat top refers to the shape of the shoulder of the carb. The round top ones looks like a wine bottle with a smooth shoulder like this http://cgi.ebay.com/ebaymotors/HIF-SU-Carburetor-AS-Fitted-to-MGB-and-Triumph_W0QQitemZ8046055950QQcategoryZ33550QQrdZ1QQcmdZViewItem The flat top have no smooth shoulder but look like this : ___|..|___<---not rounded |............| |............| |............| The flat top ones are the ones people don't like. The older 240Z engine can have some problems, one of them being not compatible with unleaded fuel, the valve seats will wear out quicker. Other problems have to do with age, worn rings, worn valve guide, worn valve guide seal can all lead to burning oil. Quote Link to comment Share on other sites More sharing options...
Initial Z Posted March 17, 2006 Author Share Posted March 17, 2006 Or... scrap the RB build and get an N42 short block with a maxima diesel crank' date=' use your L24 coneting rods, KA24 pistons, P90 head, 2mm HKS head gasket, non-egr L28 intake manifold, 420cc supra injectors and custom fuel rail, megga squirt engine managment, T3/T04 hybrid turbo, bitch'n exaust, and a few other things and BOOM! 350 rear wheel horse power... [/quote'] Um well I wasnt going to do the RB swap I want to do the SR20 swap. But any way... that build you described sounds interesting.. but I'm a begenner at mecanics so can you go into more detale about this? Or point me in the direction of more info? Whats the price of a build like that? Is it a reliable engine would it handel trips of 300+ miles in the midel of summer? thanks for the input Quote Link to comment Share on other sites More sharing options...
Initial Z Posted March 17, 2006 Author Share Posted March 17, 2006 round top or flat top refers to the shape of the shoulder of the carb. The round top ones looks like a wine bottle with a smooth shoulder like this http://cgi.ebay.com/ebaymotors/HIF-SU-Carburetor-AS-Fitted-to-MGB-and-Triumph_W0QQitemZ8046055950QQcategoryZ33550QQrdZ1QQcmdZViewItem The flat top have no smooth shoulder but look like this : ___|..|___<---not rounded |............| |............| |............| The flat top ones are the ones people don't like. The older 240Z engine can have some problems' date=' one of them being not compatible with unleaded fuel, the valve seats will wear out quicker. Other problems have to do with age, worn rings, worn valve guide, worn valve guide seal can all lead to burning oil.[/quote'] Yea, I have tha flat top stile whats so bad about them? I havent had my Z long enof to expirianc any problems. (I bought it, drove it across town, parked it in the garage, and started tering it apart:) ) Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted March 17, 2006 Share Posted March 17, 2006 I don't know why the flat tops are so hated, maybe there was an explaination in the search. I never owned a carbed Z. If you have the chance to pull the head off the engine, check the piston top. If there is a ring of clean(washed) area around the piston top, that means the oil rings have trouble scrub down the oil on the walls. As the piston pushes up, the oil on the wall washes the circumference of the piston top clean. If the piston looks normal, then check valve guides and valve stem seals. The stem seals are probably cheap to replace, it's the work involved that drive you nuts. Because I have a really bright LED flashlight, I would peek into the engine to see the piston top thru the spark plug holes. If the pistons look normal I would replace all the valve stem seals without removing the head and see how the oil burning condition improves. Quote Link to comment Share on other sites More sharing options...
AK-Z Posted March 17, 2006 Share Posted March 17, 2006 In short, the engine you have now would need a engine rebuild. I don't know either why the flat top carbs are unwanted, I just get that impresion on almost every post about the carbs, maybe because all the L26 engines came with them, and then through association. I think you can get the most HP with carbs than EFI without that many costly modifications. Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted March 17, 2006 Share Posted March 17, 2006 I hate computers:evil:... I wrote this bitch'n post that discribed how to build an L28 turbo motor with cost and horse power and all kinds of good info, then I tried to add a link and I lost it all. so here is the short version. Flat tops are boat anchors cause of E.P.A. smog regulations, more hoses and jets and make the carb work like crap. Z therapy (the SU carb rebuilder wont even take them as cores) Yes you can build a reliable 300+ HP every day driver that you can drive to vegas and back 5 days a week for about $2000. Check out this link to get you going in the right direction. http://forums.hybridz.org/showthread.php?t=84860 make sure you do your homework ... you only wanna build your motor once! Good luck and let us know what you do. Quote Link to comment Share on other sites More sharing options...
Initial Z Posted March 17, 2006 Author Share Posted March 17, 2006 Thanks for then info guys. That sucks about your poste. Sounds like you hade some good info in there. If I know I'm know I'm going to be wrighting a lot I'll do it in some kinde of word prossesing program first then cut and paste into the poste. Well if you feal up to it could you give me a list of parts and prices for rebuilding my engine into a 300hp turbo? Or if thats covered in the link you sent thats cool I havent had time to read through it all cuz I need to go to work soon. ok thanks fo rthe help. Quote Link to comment Share on other sites More sharing options...
Initial Z Posted March 18, 2006 Author Share Posted March 18, 2006 I just looked over that poste about the turbo convertion. I think i still would rather do the sr20 swap so I think I'll just do an engine rebuild at moste and save my money for the sr20. But thaks for showing me the info it was intresting to read. Quote Link to comment Share on other sites More sharing options...
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