Guest Anonymous Posted January 3, 2001 Share Posted January 3, 2001 40mm dcoe, 270/280 schneider cam, 10+ compression ratio, header on a l28. Any suggestions for main/comp jetting? I've decided to spend a coupla dollars to lean it out and get some more power and mileage, as it runs extremely rich now. It now has 125 main/175 comp jets. How much of a change would going to, say, 120 be? ie. how much smaller should I get to lean it out just a bit? It runs fine, but the plugs get extremely black and it gets really really bad mileage and blows a bit of smoke 'cause it's so rich. At $25/6, I don't want to just blindly guess, esp. since I won't be using this drivetrain for any extended amount of time! ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
JFryer Posted January 3, 2001 Share Posted January 3, 2001 What type of manifold are you running.Is it an individual runner type (Nissan comp) or is there a balance tube running between the runners (Cannon). Also what size are the ventures (chokes). For good prices on jets try www.webercarbuetors.com Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 3, 2001 Share Posted January 3, 2001 It's the cannon manifold, but there is no plugged hole at each end where I would assume they would drill the cast balance tubes out! So I dunno if they are individual or not. Finding the jets isn't a problem, just wondering how much of a change is significant - I don't want to go 1 size down and have it make no noticable difference, yet I also don't want to go too far as I can't find them locally, so all will have to be mail ordered. ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
Drax240z Posted January 3, 2001 Share Posted January 3, 2001 Morgan, try tracking down Scott Taras on zcar.com. (ZR8ED) He's a weber guy and I think he can probably help you out. Actually he's also a member here, but doesn't post a lot. ------------------ "Gimme Fuel, Gimme Fire, Gimme that which I desire" -Metallica Drax240z 1972 240z - L28TURBO transplant on the way! http://members.xoom.com/r_lewis/datsun.html http://members.home.net/drax77/newpage.html Quote Link to comment Share on other sites More sharing options...
Guest kc6wfs Posted January 4, 2001 Share Posted January 4, 2001 Hi Morgan. I had 40mm dcoe's for years! I loved the tripple webers. I have a book on webers and several sets of jets and some extra tubes. I'll never use them again. Send me a email and I'll send you the book and jets and other weber stuff I can find. The book will really help you out!!! For a quick fix I would drop the main's down one or two sizes. I think you said you were running 125's???? go down to a 115's. I was running 100's. I do think I have 6 115 or 100's as well as several sets of comp jets. If you need to buy jets, "Top End Performance" can get them for you. Send me a email to kc6wfs@pacbell.net with your address and I'll send this stuff your way. Hope it helps!! Dave Booth ------------------ www.geocities.com/kc6wfs/240z.html Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 4, 2001 Share Posted January 4, 2001 Kick ass! I read some bad stories about top end from more than 1 person, so I was gonna get them elsewhere, but I digress. I'm quite certain that the carbs are exactly as they were shipped new. The guy I bought it from made it sound like a big deal that he "synced" them regularly. I imagine he meant simply evening out the idle bleeds, as he wasn't exactly the sharpest knife in the drawer if you know what I mean. I emailed you, anything you have I'll take if it costs less than new, and free is definately less than new! Thanks a ton. ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
Guest kc6wfs Posted January 4, 2001 Share Posted January 4, 2001 I've never had a problem with them. I'm licky.. I can drive to there shop. They are about 2 miles from where I work! I'll send out the stuff tomarrow. Do you need a flow meter for sync'ing the carbs??? Do you have a pic of your linkage?? The TWM linkage kicks ass!! It's the best. It's around $200.00 I think but NEVER had to re-sync them. With the other types use some thread lock while you are syncing the carbs, once you are done let it sit over night and you won't have to touch it for a long time unless you rejet or something. Also be sure to run good air filters.. K+N or somthing. The webers are full if little air passages. I rebuilt my set one and got some crap in while syncing them.. pissed me off. Are you running velocity stacks?? They make a difference! And add a nice sound. Dave Booth ------------------ www.geocities.com/kc6wfs/240z.html Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 4, 2001 Share Posted January 4, 2001 I'm pretty sure what I have is the straight MSA setup, the guy I got the car from was a MSA whore big time. k&n filters and velocity stacks, yes. I'm not too worried about idle quality as it has to idle over 1k rpm anyhow, so it's not a problem. ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
Guest scca Posted January 4, 2001 Share Posted January 4, 2001 try http://www.overseas-auto.com/ if you call ask for Jim he's the weber guy and they buy direct from Italy so no middleman. FYI i run 50's with 46mm chokes so the 40's are small unless the motor is close to stock. ------------------ Mike mike@fonebooth.com http://www.fonebooth.com/brakes.html raceparts and brake upgrades. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 4, 2001 Share Posted January 4, 2001 Going by the weber charts, weber reccomends a bore in the low 40mm range for 2.8 liters at 7k rpm. Considering nobody drives a Z at 7k rpm all the time, I think 40 is probably quite adequate unless you car never sees anything other than a racetrack. Quote Link to comment Share on other sites More sharing options...
JFryer Posted January 4, 2001 Share Posted January 4, 2001 The Weber charts are all for individual runner systems. Iff you are running the cannon manifold you can go much smaller. I would bet that your cannon manifold is like mine and the balance tube is cast open with no plugs on the ends. Also if your system probably has 28mm venturies which are alittle small for a hot 2.8 I currently run 32's but not a big deal, only about a 30-40 CFM differance in air flow if I remember. About 160CFM per barrel for 28's vs 180CFM per barrel for 32's. This is not exact as the numbers required interpolating off of a chart. Last but not least when I was running 28's in my car I tried 110 mains but could still not get the car to lean out. I then called the guys over at Top end. They recommended that I go with the bigger ventures. according to them, when you run a large motor on small ventures the airflow is to high which causes even higher fuel flow. this would normally be compansated for by a larger air correction jet. But because of the small ventures this large fuel flow happens below the level at which the air correction jets start making a real differance. and instead would have to be compansated for by emulsion tube's which unless you have tons of money and a engine dyno are best left to the pro's. Also new ventures are about $10-12$ each ------------------ Jeremy Fryer Early 74 260Z Worked hard and put up wet Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 5, 2001 Share Posted January 5, 2001 Yeah, I was actually wondering about using larger venturis.... higher pressure would suck less fuel, as well as having better airflow. Argh. I think I'm just gonna leave them like they are now. Too much effort and money to fiddle with them and then just get rid of the engine! ------------------ Morgan http://z31.com/~morgan/s30 http://carfiche.com Quote Link to comment Share on other sites More sharing options...
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