steve260z Posted March 5, 2015 Share Posted March 5, 2015 Running the car with jet stack out gives ya an excellent "view" of how often you're on the idles/progression holes. One misconception is that people think the main jets come on at some certain rpm..Not So. The main jets come on at a certain butterfly position. You can be at 5,000 rpm and very partial throttle and be running nothing but idle jets. Hell, I got my car up to 60mph with the main jet stack sitting in the garage. Now, I wouldn't adjust the float levels for the idle jets. Yes, I assume it would have some impact but you need to focus the float level for the main jet. As you mentioned in an earlier post. Quote Link to comment Share on other sites More sharing options...
adam. Posted March 5, 2015 Author Share Posted March 5, 2015 OK, noted Steve, regarding adjustment of floats for idle jet. And you can definitely run the car without the mains installed. There has been a delay in ordering and receiving of the new jets so no new information to be mentioned. It should hopefully be here by early next week. I have access to a dyno at work again which will help dial everything in. And I think my OER emulsion tube and jets should do for the moment! Will get too expensive otherwise Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 5, 2015 Share Posted March 5, 2015 (edited) Running the car with jet stack out gives ya an excellent "view" of how often you're on the idles/progression holes. One misconception is that people think the main jets come on at some certain rpm..Not So. The main jets come on at a certain butterfly position. You can be at 5,000 rpm and very partial throttle and be running nothing but idle jets. Hell, I got my car up to 60mph with the main jet stack sitting in the garage. Now, I wouldn't adjust the float levels for the idle jets. Yes, I assume it would have some impact but you need to focus the float level for the main jet. As you mentioned in an earlier post. This is why you run the top gear test at progressively more throttle angle. On Mikunis it's well known highway cruise is done on idle jets. Mikuni specifically states at WOT you are tipping into the main transition at 3,000 RPMs as I recall (if their other parameters regarding sizing the carbs are followed.) That pretty much is what I've used to explain to people why fiddling with a main jet for mixture adjustment below that point is basically fruitless. There isn't enough draw to top the mountain as it were...to get fuel flowing down into the boosters before that point. Edited March 5, 2015 by Tony D Quote Link to comment Share on other sites More sharing options...
adam. Posted March 14, 2015 Author Share Posted March 14, 2015 (edited) Update:I checked the timing and I don't know how you guys do it but it seems like the motor is reving too fast to tell what exactly the timing is at 3krpms.I have received #55 and #57.5 idle jets, the #55s are still too lean to even accelerate, while the #57.5s have a cruise AFR of 12.5 and acceleration is in the 13s - 14/15 which cause stuttering (around 2.3-3krpms). Idle is about 13.Any ideas what could cause this lean spot causing the stutter? I cannot get my head around it. I have tried checking timing and best I can do is 15 degrees at idle.It seems like I can't get cruise any leaner without causing hesitation on acceleration. I'm guessing it's that dreaded transition to the mains.. Edited March 14, 2015 by adam. Quote Link to comment Share on other sites More sharing options...
steve260z Posted March 14, 2015 Share Posted March 14, 2015 (edited) I checked the timing and I don't know how you guys do it but it seems like the motor is reving too fast to tell what exactly the timing is at 3krpms. If you are saying the timing mark is bouncing all over the place and you can't get a reading? That means two things. The dizzy is not holding a consistent timing or the timing light is not working correctly. The 2nd not being likely. Make sure the plug is gapped correctly, swap the ignition wire out with another from 2 through 6 and try again. And I just realized you have a 240..Are you still running points? Edited March 14, 2015 by steve260z Quote Link to comment Share on other sites More sharing options...
madkaw Posted March 14, 2015 Share Posted March 14, 2015 Revving to fast? You just need to be above the proper rpm to make sure you have all your mechanical advance in. Transition can be a bitch to figure out. I fought it for a long time . I got it down to just a mild hiccup every once in a while. Quote Link to comment Share on other sites More sharing options...
zguitar71 Posted March 16, 2015 Share Posted March 16, 2015 Try adjusting the pump jet screw to give a little more pump duration. Possible that could help the lean acceleration prob from 2.3-3k. Don't know if it will work but worth a try. Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 18, 2015 Share Posted March 18, 2015 "Shift, ctrl Arrow Up Up Up" People who say 'carbs are easy' have never really done anything but bolt on something that runs 'pigbog rich' and were satisfied by it. I know what I would do with a Megasquirt...go add fuel ONLY in the MAP Blocks where the stumble was happening. OR Move the timing up.... It is done sequentially, you don't even slow down just run through the area....lift....make the adjustment and go back up through it again to see what it did...next load cell/transition point... Quote Link to comment Share on other sites More sharing options...
adam. Posted March 18, 2015 Author Share Posted March 18, 2015 (edited) I will need to double check using a different timing light as the one I'm using is a bit dodgy actually. And I'm running a 280zx electronic distributor. I don't think increasing the pump will do much as the lean is a few seconds after the throttle is pushed. I will need to have a play around with the float levels I think. And it may be hard to tune now but that satisfaction of having done it will be worth it. I could have easily paid someone to set these up but money can't buy experience. Edited March 18, 2015 by adam. Quote Link to comment Share on other sites More sharing options...
zguitar71 Posted March 19, 2015 Share Posted March 19, 2015 I don't think increasing the pump will do much as the lean is a few seconds after the throttle is pushed. The OER pump adjustment screw dials the amount of time the pump last. Dialing it up will make the stream of fuel pumped into the intake last longer so it might help in your case. Unless you are pressing the throttle and the taking your foot off and then it goes lean. If you are pressing it and keeping it down and it goes lean the increase in duration will keep up with the amount of time the throttle stays depressed. Quote Link to comment Share on other sites More sharing options...
adam. Posted March 19, 2015 Author Share Posted March 19, 2015 Is that so? Interesting because I did not know that.. It is leaning out while my foot has been down for a few moments. I will have to experiment with it also. Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 19, 2015 Share Posted March 19, 2015 If it leans out with your foot down for a few seconds the jet it's on is either too lean, or the air bleed / e-tube is doing something at that rpm range. Quote Link to comment Share on other sites More sharing options...
adam. Posted March 20, 2015 Author Share Posted March 20, 2015 What confuses me is that it may run lean on acceleration but it will run rich at 12.5:1 AFR on cruise.. I will need to double check timing, float levels, throttle position etc. Quote Link to comment Share on other sites More sharing options...
steve260z Posted March 20, 2015 Share Posted March 20, 2015 12.5 is not bad. Cruise AFR is determined by your idle jet. BTW if you adjust the timing once u figure out what your timing is all these AFRs will likely change up. Quote Link to comment Share on other sites More sharing options...
madkaw Posted March 20, 2015 Share Posted March 20, 2015 I wouldn't be happy with 12.5 cruise. That's even a bit rich for WOT. My engine would show lean under moderate acceleration but fine WOT. I messed with the bleed pipes until I negated the stumble- Then my engine went all to hell Quote Link to comment Share on other sites More sharing options...
zguitar71 Posted March 20, 2015 Share Posted March 20, 2015 (edited) Is that so? Interesting because I did not know that.. It is leaning out while my foot has been down for a few moments. I will have to experiment with it also. Yea. The adjustment screw is on the top center at the motor side of the carb. They are delicate so be careful but it is unique to OER I believe and a pretty cool thing. The float adjustment is nice too. http://www.racetep.com/tepoer.html There is a picture of it here. Better pic here http://lupinusflower.ocnk.net/product/9 Edited March 20, 2015 by zguitar71 Quote Link to comment Share on other sites More sharing options...
gacksen Posted March 21, 2015 Share Posted March 21, 2015 Yea. The adjustment screw is on the top center at the motor side of the carb. They are delicate so be careful but it is unique to OER I believe and a pretty cool thing. The float adjustment is nice too. http://www.racetep.com/tepoer.html There is a picture of it here. Better pic here http://lupinusflower.ocnk.net/product/9 thats a great feature ! once my AFR gauge is in i will mess with the e tubes. got some jb weld to get that bog sorted... Quote Link to comment Share on other sites More sharing options...
adam. Posted March 22, 2015 Author Share Posted March 22, 2015 Yeah, I am aware of the float adjustment as well as the accelerator pump adjustment screws but if I must be completely honest, I thought the pump adjustment was more to do with its 'load' or amount of fuel it releases, not duration of its fuel release. I will have to have an experiment with that though to confirm. Been too busy with work to really have a play. Quote Link to comment Share on other sites More sharing options...
Tony D Posted March 22, 2015 Share Posted March 22, 2015 If you need only a small enrichment relative to jet sizing...you can alter the float level a small amount. Higher will give you richer, lower will give you leaner...usually across the board. Quote Link to comment Share on other sites More sharing options...
adam. Posted March 29, 2015 Author Share Posted March 29, 2015 So the solution to my lean hesitation with the #55 pilots installed was to simply adjust the pilot screws/idle adjustment screws out another half turn or so.. Putting them around 2.25 turns out from full lean (ideal is 2 turns +/- half a turn). With the #55s installed, 29mm fuel float level and 2.25 turns of the pilot screws, the car cruises with an AFR of 13.5, idles rich around 12.5-13, but light acceleration is now smooth being around 13:1 AFR and creeping up to about 14:1 in second gear. Although idle is a tad rich, drive ability has improved which I guess is more important in this situation. OER pilot jets do not allow you to change air hole sizes like Webers to assist idle mixtures and cruise mixtures independently so this will have to do. WOT is currently around 12.5-13 which I think is spot on but goes a tad rich in the upper rev limit which is telling me I need larger air correctors which I currently don't have, but that's easy in comparison to slow speed accelerations and cruise stuff. That is all. thought I'd give you all an update! Quote Link to comment Share on other sites More sharing options...
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