HakosukaJD Posted January 12, 2006 Share Posted January 12, 2006 The latter list was the carb setup right after I bought it. N42 head and block. Unknown internals. Cam is stamped with HKS and L20...but no idea if it actually an L20 cam. No numbers on the back end to indicate lift/duration.... I moved down to 165's when I was blowing black smoke at high RPM's. The first list is my setup as of now. The original setup is starting to make me wonder if the engine is more wound up then I originally believed..... Thanks for the advise. What kind of power are you making? Earlier you said your mains were 165's. Now they are said to be 190. Is that correct. Way too big.If your venturis are in fact 41' date=' the car will be totally undrivable for the street. 41 is the largest that Mikuni makes. I recommend size 34 for the street. Then drop the size of the main and air jets. My mild L28 current runs the following. Venturi 34 Main 135 Air 180 Pilot 60[/quote'] Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 12, 2006 Share Posted January 12, 2006 I drove on the street with 37s, in traffic, with a big cam, lightweight flywheel, and stiffer than stock clutch for a LONG time. No problems. I think the 41s might be agressive, but shouldn't prevent you from driving the car on the street. Definitely put them back in though. I would: Reinstall chokes synch carbs Install a cheap one wire narrow band O2 This will cost you a grand total of about $40 US, and then you'll be able to watch the air/fuel mix all the time with a voltmeter. Yes, the narrowband isn't as accurate as a wideband, but you can get it a hell of a lot closer, then take it to the dyno and fine tune with their wideband O2. If you can't get it running to your satisfaction with simple jetting changes, then step down to 34's or 37's. Just my $.02 Quote Link to comment Share on other sites More sharing options...
AdrianZ Posted January 12, 2006 Share Posted January 12, 2006 wow my webers are running rich and after reading on how to tune them. it seems like such a pain in the butt. i know know why i love fuel injection Quote Link to comment Share on other sites More sharing options...
briann510 Posted January 13, 2006 Share Posted January 13, 2006 wow my webers are running rich and after reading on how to tune them. it seems like such a pain in the butt. i know know why i love fuel injection Triple Mikunis are not hard to jet. 1 trip to the dyno and an hour later they should be jetted just fine and never need another adjustment. I can change out my jets on all 3 carbs in 5 minutes if need be for a severe temperature change, but so far in the last year they have remained unchanged. Quote Link to comment Share on other sites More sharing options...
twistex Posted January 15, 2006 Share Posted January 15, 2006 I just put a set of 45mm sk racing carbs on my 3.2 liter last night and fired it up this morning. runs great.. getting them sync'd together seems to be the big hastle .. havnt been able to get it on the road yet im also doing some suspenion work. i wana bring it to the dyno also so i can fine tune it. I could see daily driving sidedrafts mikuni sk or webers. I use to daily drive my 510 and 1200 with both mikuni and weber sidedrafts on ka24de twin cam motors no problem. Put it this way if somone gave me the option to have efi or a heater in my z i would probably pick a heater ! hahaha Quote Link to comment Share on other sites More sharing options...
HakosukaJD Posted January 24, 2006 Share Posted January 24, 2006 Okay...Chokes back in. Carbs synched (the butterfly valve post on my center carb was slightly torqued, but I seem to have torqued it back). Waiting on the O2 from the U.S.... Car doesn't fall flat when I stomp the gas anymore.....but it is difficult to get the idle right. I had 1.5 turns on the pilot screws, but even when I back the linkages all the way off, I'm getting about 1200 RPM. I went to about 1.25 turns on all pilot screws and between 1/8 and a 1/4 turn between the three linkages to bring it down to just over 1000. Should I back down on all pilot screws to 1 turn to get the RPMs down a little more? I drove on the street with 37s' date=' in traffic, with a big cam, lightweight flywheel, and stiffer than stock clutch for a LONG time. No problems. I think the 41s might be agressive, but shouldn't prevent you from driving the car on the street. Definitely put them back in though. I would: Reinstall chokes synch carbs Install a cheap one wire narrow band O2 This will cost you a grand total of about $40 US, and then you'll be able to watch the air/fuel mix all the time with a voltmeter. Yes, the narrowband isn't as accurate as a wideband, but you can get it a hell of a lot closer, then take it to the dyno and fine tune with their wideband O2. If you can't get it running to your satisfaction with simple jetting changes, then step down to 34's or 37's. Just my $.02[/quote'] Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted January 24, 2006 Share Posted January 24, 2006 What is the static timing? It should be up around 12 btdc with triples. If there are vacuum leaks or the timing is close to stock you'll never get it to idle proper. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 24, 2006 Share Posted January 24, 2006 Okay...Chokes back in. Carbs synched (the butterfly valve post on my center carb was slightly torqued' date=' but I seem to have torqued it back). Waiting on the O2 from the U.S.... Car doesn't fall flat when I stomp the gas anymore.....but it is difficult to get the idle right. I had 1.5 turns on the pilot screws, but even when I back the linkages all the way off, I'm getting about 1200 RPM. I went to about 1.25 turns on all pilot screws and between 1/8 and a 1/4 turn between the three linkages to bring it down to just over 1000. Should I back down on all pilot screws to 1 turn to get the RPMs down a little more?[/quote'] Check the linkage at the throttle stop on the side of the carbs really closely. I had to shorten one of the arms that goes from the carbs to the shaft to get it to close all the way. Back off the screws on the throttle stops, then adjust the arms, then adjust the screw on the stop again to try and get the idle you want. If it just won't come down low enough, then you need a smaller pilot--I DON'T THINK THIS IS YOUR PROBLEM. I'd really really really make SURE the linkage is working properly and that all of the screws are bottoming out on the stops as I haven't run into a problem getting mine to idle low enough with bigger pilots than you have. Quote Link to comment Share on other sites More sharing options...
HakosukaJD Posted January 28, 2006 Share Posted January 28, 2006 14 deg BTDC. As for the other stuff. Looking at the plugs made it readily apparent it was #4 that was running the richest....the others weren't too bad. I readjusted all the linkages (carb 1 linkage was indeed off). Reset the pilot screws to 1.5 turns and was able to hit 900RPM no problem with the throttle screws. Unfortunately, my center carb is not balanced across itself. #3cyl is pulling around 2 kg/min while #4cyl is pulling almost 4. I backed the throttle screw all the way out and pulled off the center carb and looking through it, could see light coming around the butterfly valve on 4 and a touch on 3. I'm assuming I should see either no light, or the same through both (otherwise would lead to imbalanced air regulation). I'm unable to accurately determine whether the valve itself is bent, or just the valve arm. What is the static timing? It should be up around 12 btdc with triples. If there are vacuum leaks or the timing is close to stock you'll never get it to idle proper. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 28, 2006 Share Posted January 28, 2006 I readjusted all the linkages (carb 1 linkage was indeed off). Reset the pilot screws to 1.5 turns and was able to hit 900RPM no problem with the throttle screws. Unfortunately' date=' my center carb is not balanced across itself. #3cyl is pulling around 2 kg/min while #4cyl is pulling almost 4. I backed the throttle screw all the way out and pulled off the center carb and looking through it, could see light coming around the butterfly valve on 4 and a touch on 3. I'm assuming I should see either no light, or the same through both (otherwise would lead to imbalanced air regulation). I'm unable to accurately determine whether the valve itself is bent, or just the valve arm.[/quote'] GREAT! I'd call it good. The throttle shafts are either machined poorly or the butterflies get tweaked. Either way it's pretty common for one barrel to be just slightly open while the other is closed. A friend of mine has the exact same problem on his dual Mikunis. The important thing is that you were able to get the idle down. I know it's possible to tweak either the shaft or the throttle plates themselves to fix if you really want to. I've never done it myself, and it sounds a bit complicated. If you tweak the butterfly then how does it seal against the housing, and if you tweak the shaft, it would still need to be perfectly straight to slide it back into the side of the carb. Quote Link to comment Share on other sites More sharing options...
HakosukaJD Posted January 28, 2006 Share Posted January 28, 2006 So would you recommend synching to the high, or low barrel? Low barrel would give me a lean condition in the high. High barrel would give me a rich in the low..... Or does it really not matter when the butterfly valve is open, say, at 3/4 throttle? IE the flow is so much higher than the difference between the two.... I went ahead and synched low to help out with the mileage for now. By the way...this forum and you in particular, RULE! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 28, 2006 Share Posted January 28, 2006 It's not really going to matter that much, because like you said when they are both open that slight angle of the butterfly won't matter. Quote Link to comment Share on other sites More sharing options...
heavy85 Posted January 30, 2006 Share Posted January 30, 2006 Unfortunately' date=' my center carb is not balanced across itself. #3cyl is pulling around 2 kg/min while #4cyl is pulling almost 4. I backed the throttle screw all the way out and pulled off the center carb and looking through it, could see light coming around the butterfly valve on 4 and a touch on 3. I'm assuming I should see either no light, or the same through both (otherwise would lead to imbalanced air regulation). I'm unable to accurately determine whether the valve itself is bent, or just the valve arm. [/quote'] I had this same problem but didn't realize it at the time ... ended up rebuilding the whole engine since a couple cylinders were 'dead' ... but the engine ended up being trashed anyway so no harm done (broken rings despite good compression, scored up journals and bearings, etc). It's simple enough to get them back in line you just have to be careful and patient. Basically hold one end of the shaft and twist the other end - but be careful because you are trying to slightly yield the shaft back in line but once it starts to yield it will go really quick (dont ask me how I know). I found this on two of the three carbs and is probably the biggest PITA of setting them up other than the stupid raw fuel smell which I cant get rid of. I started by trying to get the same amount of daylight through each one but still there was still a slight different with the sync gauge which is where I got a little too agressive. Between these carbs and their raw fuel smell I'm starting to think how much I could get for my L6 stuff and just to to a V8 ... tripples, turbo motor, spare random L24, blow through SU turbo set-up, .... hmm tempting. Cameron Quote Link to comment Share on other sites More sharing options...
HakosukaJD Posted August 20, 2006 Share Posted August 20, 2006 Thread resurrection.... Had an issue with a mounting post and pin for the float on my center carb....float was stuck down and gas was just streaming right out of the throats and all over the exhaust when I cut the ignition...lucky I didn't burn the car to the ground. That corrected, realised it had fouled my plugs. Spare plugs gapped and placed...car is running again. So I'm getting ready to put in an LM-1 WB O2 (wife bought for my birthday...WEE!). My questions is...should I install multiple bungs? Would it do me any good to place a bung on a pipe from each Carb (ie exhaust pipe from cyl's 1,3, and 5) and in the converging pipe prior to the cat to get an overall? Is this overkill/waste of time? Should I just put the one in the collector? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 21, 2006 Share Posted August 21, 2006 I know of a couple racers who have adjusted each cylinder independently. I think it's overkill for everything but the most highly tuned race engine. Quote Link to comment Share on other sites More sharing options...
Silent Posted August 25, 2006 Share Posted August 25, 2006 if you get frustrated, i can offer up my su's, with mild work, ported n36 runners, for a trade. Quote Link to comment Share on other sites More sharing options...
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