yetterben Posted September 6, 2009 Share Posted September 6, 2009 what timing should i go for. Its at 14 btdc now. Quote Link to comment Share on other sites More sharing options...
Lazeum Posted September 6, 2009 Share Posted September 6, 2009 what timing should i go for. Its at 14 btdc now. According to others, 14-18 btdc should be the way to go with Webers and 34-36° total. Every car is different thou, you'll have to test to check what you should achieve (more degreee is not always better neither) Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 6, 2009 Share Posted September 6, 2009 Well i have a zx dizzy so that at most is 9 degrees advance. Which means with no vacume 23 total. Or am i missing something. Quote Link to comment Share on other sites More sharing options...
Lazeum Posted September 6, 2009 Share Posted September 6, 2009 Well i have a zx dizzy so that at most is 9 degrees advance. Which means with no vacume 23 total. Or am i missing something. Yes, you are missing something, it should be 2x9 not only 9 (because the dizzy turns once whereas engine turns twice to do one full cycle - 4 stroke engine ). So you should be around 32° then which should be good. Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 6, 2009 Share Posted September 6, 2009 farking DUH. lol Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 10, 2009 Share Posted September 10, 2009 okay here is my run down. f11 e tube 200 air corrector 140 main 33 choke 45 aux venturi car drives fine up till about 1/3rd throttle until 3 grand punch it at 3 grand car pulls hard till 5,550 then it seems to slow down revs till 7 but not as fast as the su's seems a little rich up there Another situation. one of my aux venturi fell out how who knows. the little lock down piece is no where to be found. Small ding on the end of venturi where air horn goes. I inserted it back into the carb lined up like it should be. Car drives like ass now over 1/4 throttle. I dont know if the venturi is spinning in the bore or if something else happened Hope the car did not eat the lock down tab thingy on the venturi. Still idles fine drives fine until you give it more than 1/4 then its bog city. Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 10, 2009 Share Posted September 10, 2009 I am guessing i dont have it dead on for the main jet entry. anyone have one of those little springs for the 40's damn. As far as high end should i raise the air corrector or lower the jet. Quote Link to comment Share on other sites More sharing options...
Lazeum Posted September 10, 2009 Share Posted September 10, 2009 You start to ask very specific question. I don't think we have enough info to answer so far. Head, head work? Cam Spec? timing? Regarding Aux venturi, I have no idea. Have you checked how the throttles move inside the bore? you might have something else that has moved. Then your question regarding power after 5.5k, it is difficult to answer with no data. I would try to go with smaller air jets (richer to be safe) and see if it improves, if not, try to go bigger. If your cam is stock, loss of power after 5.5k would not surprise me. I found a wideband sensor to be an amazing tool. You should try to get one or to borrow one to check where you stand. You should find some around 300$. In the long run, it might cost less money than the library you might end up with to run Webers how they should Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 10, 2009 Share Posted September 10, 2009 Motor is stock as far as i know. Revved happily with the su's all the way and pulled like a mutha. The other issue only started after the aux venturi fell out. So i dont think it is lined back up in the bore or its vibrating not allowing the fuel to come in the right way threw the bore. Timing set to 32 or so all in at 2,500 Motor is f54 flat tops with p79. Low end response is great no stumble torqy feel. I think its the natur of the beast that you cant just floor it at 1,500 and expect to to do anything but bog. Like i said its fine up till 1/3rd throttle until about 3 grand than its on it seems. It will pull till 7 grand just not as hard it seems tas the su's. Wideband is on the way. IT jsut feels sluggy up top and the plugs show it too. Quote Link to comment Share on other sites More sharing options...
zman71 Posted September 10, 2009 Share Posted September 10, 2009 Can anyone offer any suggestions on tunning my triple weber carbs on my L-28 1971 Datsun 240z engine. Nobody in south florida seems to know how to tune these carbs. I purchased 45 DCOE Triple Weber Carbs from MSA that I figured would be the correct set up for my Z. Here the engine set up I currently have: 45 DCOE Triple Weber Carbs from MSA Stage two performance cam package from MSA Electric water pump from MSA Electric gas pump from MSA Six in one headers from MSA Two and a half inch turbo exhaust from MSA Performance coil from MSA Fuel regulator N42 head Iriridium NGK spark plugs Not sure if anyone is running the same type of set up and could share there jet size, emms tube size etc.... PLEASE HELP!!!!!! Quote Link to comment Share on other sites More sharing options...
Lazeum Posted September 10, 2009 Share Posted September 10, 2009 To be very honest, you should try to read books first Books on the following link about Webers are great source of info that should allow you to start on your own. http://www.carburetion.com/books.asp Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 10, 2009 Share Posted September 10, 2009 Got a new aux venturi today. She runs like a raped ape butt dyno is happy. Another qualm though. i pulled my plugs to check the readings and stuck a little led bendy light down in my bores. My piston tops where covered in carbon before. I was running sm su's now i see what appears to be a pepper liek thing going on but it is carbon lifting off the head. SO i dont know if i am way lean up top or not. So i dont know if i am just running cleaner than ever before and its cooking carbon off or what. 700 feet above sea level 200 air 140 main 33 choke no dead spots no issues just a little worried about the carbon flaking. Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 10, 2009 Share Posted September 10, 2009 I went outside to re-examine the pistons. I took a real long soft toothpick and gently brushed the deposits. Its ash white ash over the carbon. It was really pronounced it cyl1. So what is it old carbon cooking off? plugs all seem to be fine. Carbs are balnced pretty good with unisyn. Pulling each plug wire makes it drop like 10-15 rpm all across the board. Cant wait till wideband gets here. kinda looks like the 1st picture but its not over the whole head. http://images.google.com/imgres?imgurl=http://www.theultralightplace.com/images/piston1a.jpg&imgrefurl=http://www.theultralightplace.com/pistons.htm&usg=__8e-0rxo9Y_plOdv-_XgPHKe7GWk=&h=254&w=199&sz=8&hl=en&start=15&um=1&tbnid=7jyN4UFhPpUdKM:&tbnh=111&tbnw=87&prev=/images%3Fq%3Dwhite%2Bash%2Bpiston%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DN%26um%3D1 it could be i guess the car is running optimal for the first time in a long time. I just got it like 6 months ago and the last guy had some blown out su's running pig rich like black smoke everywhere rich. Only other change lately besides the webers has been vr1 zddp oil for the last 100 miles or so. Ash seems to have started from where the plug fires onto the top. Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 11, 2009 Share Posted September 11, 2009 I can clean cyl6 all the way down to a like new finish with a qtip........starting to really worry me if i was running to lean or what. Should i drop the air corrector back to 175? I have no idea what a piston is supposed to look liek under normal conditions if it should look nice and clean or have deposits on it. I have some dished l28 pistons here from a FI motor they have some pretty heavy deposits on them. Its like the cyl are self cleaning lol but i know there not....... Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 11, 2009 Share Posted September 11, 2009 I am wondering now if i am in fact to rich. The deposits are kinda wet and can be removed very easy. The car runs so damn good though. Of course these are all wot pulls. I might just drive it normally for a few days and check again. Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 15, 2009 Share Posted September 15, 2009 Got her tuned in today. 12.7 for wot pulls. Holy crap I don't know what i gained for hp over the SU's but its a hell of a jolt that's for sure. Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 16, 2009 Share Posted September 16, 2009 I have read this whole thread again and the only thing i can conclude is the more engines changes you make, the more out of whack your tuning parameters go. I had no real hard time setting them up from scratch. But i am fairly stock l28. I guess you start adding cams and so on the engine pulses diffrently changing the way the carb works. In the rotary world the only real way to tune a weber or 2 barrel is wot. You live with everything in between. It works this way do to the way the rotary pulses and its vacuum signal works. I think the further and further you deviate from the norm the more and more its gonna suck on the street. These carbs where added to these cars with one implied use wot at a track, or a constant rpm rate it seems. Quote Link to comment Share on other sites More sharing options...
2eighTZ4me Posted September 16, 2009 Share Posted September 16, 2009 Maybe I just got lucky. I bought a set of Mikuni 44's (carbs only) and put them on a Canon intake. No prior knowledge of them, other than they cam off a road race car (2.8L) I have a 3.1 stroker and a fairly radical Racer Brown cam. I still have the customary lean spot coming from off-idle, but from about 2.5 grand on up, I'm at 12.8 all the way up to 7K. No bumps or lean spots throughout the rpm range - flat line all the way up to redline. The car is extremely street friendly as well. I "could" drive it every day - but maybe I'm a little more forgiving in what I can put up with as opposed to others. Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 17, 2009 Share Posted September 17, 2009 That's the thing i have no lean stumble at all off idle or any part of the band. I mean if i floor it off the line the car will die but they all will. But other than that no lean. Maybe i too am just more tolerant I did drive a perephial port 13b on the street. Quote Link to comment Share on other sites More sharing options...
yetterben Posted September 20, 2009 Share Posted September 20, 2009 Okay decided power band that goes from 4 up is just not cool for the street fun yes but not to cool for alot of low end stuff. so i have 33's in it now and i have a set of 30's here. I assume i need to drop the main and the corrector down to suit. What about idle? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.