Leon Posted October 31, 2014 Share Posted October 31, 2014 Taking a quick look at that chart, 60F6 idles might do the trick. If the 60 series is just generally too rich, you can also try 55F7 as it has twice the air bleed area as the F11. Maybe give those a try if you can find them. Quote Link to comment Share on other sites More sharing options...
steve260z Posted November 1, 2014 Share Posted November 1, 2014 On the chart where is the 55 or 60 number derived from. It's the size of the fuel hole in mm correct? 55 is .55 of a mm.....? Quote Link to comment Share on other sites More sharing options...
zredbaron Posted November 1, 2014 Share Posted November 1, 2014 "Weber main jet sizing nomenclature refers to the flow rate in hundredths of a millimeter (0.01mm). A 150 main jet, for example, flows the same as a perfect hole with a 1.50mm diameter." This is important. You never, ever want to use jets that have been drilled by anyone other than Weber, because Weber flow tests all jets and *then* stamps their flow rate. "Size" isn't as important as its usefulness, after all... Quote Link to comment Share on other sites More sharing options...
steve260z Posted November 8, 2014 Share Posted November 8, 2014 I installed 50F8 idle jets. AFR is a bit lean at cruising. In the high 13s but have large tip in stumble. (Hello Leon). Starting from a stop light the car will hesitate, buck then start flying but the hesitation is large. Now, since I'm running 36mm chokes maybe that's the cause. I still have the F7s in there. Currently working on the idle jets. Help on the tip in? Quote Link to comment Share on other sites More sharing options...
Leon Posted November 9, 2014 Share Posted November 9, 2014 I installed 50F8 idle jets. AFR is a bit lean at cruising. In the high 13s but have large tip in stumble. (Hello Leon). Starting from a stop light the car will hesitate, buck then start flying but the hesitation is large. Now, since I'm running 36mm chokes maybe that's the cause. I still have the F7s in there. Currently working on the idle jets. Help on the tip in? I'd say high 13s is a bit rich at cruising. I shoot for low-to-mid 14s. Sounds like you may have an off-idle stumble which is different from a tip-in stumble. Here is the test to determine this: Start with a warm car, let it idle. Slowly raise idle speed with an idle speed screw or very slowly by hand and see if it stumbles as you do so. If your idle jet selection is dead-on and it still stumbles, your progressive holes are not positioned right and you need to drill another one. The other case is that your idle jets are too lean on the low end (too big of an idle air bleed)... Quote Link to comment Share on other sites More sharing options...
steve260z Posted November 23, 2014 Share Posted November 23, 2014 (edited) I'd say high 13s is a bit rich at cruising. I shoot for low-to-mid 14s. Sounds like you may have an off-idle stumble which is different from a tip-in stumble. Here is the test to determine this: Start with a warm car, let it idle. Slowly raise idle speed with an idle speed screw or very slowly by hand and see if it stumbles as you do so. If your idle jet selection is dead-on and it still stumbles, your progressive holes are not positioned right and you need to drill another one. The other case is that your idle jets are too lean on the low end (too big of an idle air bleed)... Sorry for the delay, trying to get this Mallory Distributor working correctly. But, I performed the above test and I can raise the idle just fine. I raised it very slowly by hand on the linkage. hum.... Edited November 23, 2014 by steve260z Quote Link to comment Share on other sites More sharing options...
Leon Posted November 23, 2014 Share Posted November 23, 2014 See my last sentence. Also, that Mallory probably isn't doing you any favors. I'd toss it and go for either a Nissan unit or the 123ignition one. I plan to get a 123 myself but haven't reached that point yet, the Z has been down for over a year... Quote Link to comment Share on other sites More sharing options...
steve260z Posted December 7, 2014 Share Posted December 7, 2014 Ok, after much tuning and more to come I have a strange issue. In stalled the 50f8 idle jets. I've advanced the timing more and that got rid of the backfiring under off throttle. My AFR is pretty good across all driving situations. A bit rich but ok. Cruising at around 2,500 I'm at around 13-14. But, at stand still idle I'm at 11.2. Very rich. I still have a flat spot at 2,500 under acceleration and I'm thinking a smaller idle jet will increase that problem. Just seems strange my stand still idle would be so rich. Any suggestions.? Quote Link to comment Share on other sites More sharing options...
AZGhost623 Posted December 7, 2014 Share Posted December 7, 2014 (edited) these triples run rich from my experience, and from what I have seen and read on the internet backs that up too. The flat spot/stumble is a lean spot. It could be one of the carbs itself or it could be all of them. Check the plugs to see if they are consistent looking between all of them. Make sure they are all pulling the same amount of vacuum and adjust as needed. FWIW My idle is also around 11ish. Normal driving is 13-15ish, full WOT is 11-12ish. Edited December 7, 2014 by AZGhost623 Quote Link to comment Share on other sites More sharing options...
steve260z Posted December 7, 2014 Share Posted December 7, 2014 Az, you remember what your jet set is? Or is it in the thread somewhere? My AFRs are very similar to yours. Quote Link to comment Share on other sites More sharing options...
AZGhost623 Posted December 7, 2014 Share Posted December 7, 2014 (edited) Its changed... 38 choke 160 main 230 air 60F9 F7 Tube 00 Pump 45 Pump Jet Initial Timing is 14, all in at 34. Anything below 60F9 doesnt work for me with the lean spot. Was supposed to get it dyno tuned a few weeks ago, but got horrible food poisoning and wasnt able to make it out there. Im set to redo my dyno tune on the 12/22 when I have vacation for 2 weeks. I have pretty much every combination you can do for jets, tubes and such, so we will see where I end up. Edited December 7, 2014 by AZGhost623 Quote Link to comment Share on other sites More sharing options...
steve260z Posted December 7, 2014 Share Posted December 7, 2014 Good deal. Post the results Quote Link to comment Share on other sites More sharing options...
AZGhost623 Posted December 24, 2014 Share Posted December 24, 2014 (edited) Spent all day at the Dyno shop on 12/22/14, but ran out of parts to keep testing. They were very thorough, except when it came to testing emulsion tubes. They immediately took out my F7 and replaced it with an F11. Must be the goto tube or something. They plugged right into my O2 sensor on my exhaust for AFR readings on their computer. They rebalanced my carbs, and set ignition timing and my rev limiter as well. So this is where we ended up. Which is not too great but works for now (I did yield 214hp). Mid range is definately a lot more punchy now. Instant pulls from any gear when rolling. Freeway driving Im at 3000 rpm due to my gearing so Im at the start of the sweet spot. Stop light starts, not soo good. You want your AFR (right side on 2nd picture) to be as flat as possible around 13. You can see I now start off really lean (which I noticed driving home in stop/go traffic on the freeway). Midrange is a tad rich now, with high end being about where it needs to be. The shop recommended to go with a bigger choke and bigger main jet and see what happens, but as Leon pointed out, thats just going to cause my low end rpm range to be even worse. So I may try and switch out to F7's again since they were a bit rich and see what shows up. Maybe a bigger pump jet to bring that initial in? Unfortunately I did NOT get a dyno sheet that showed what my car produced when they first tested it. All I got was final results. So to sum up... I need to gain 1 to 1.5 points in my mid range, and bring in my low end as well. Thoughts? Suggestions? it also would be helpful for me to find a cheap datalogger for this AEM UEGO AFR setup I have. 38 Choke 145 Main 165 AC 65F9 F11 0 bleeds 45 pump jet Edited December 24, 2014 by AZGhost623 Quote Link to comment Share on other sites More sharing options...
gacksen Posted December 24, 2014 Share Posted December 24, 2014 had been on the dyno last week. as for the 152 chokes went from 40 to 36 and from mains 155 down to 140. ac had been 200 previously and now is 195. first street run had been with 40 pumps and 0.4 bleeds and 60f8 idle. had not been workable. the typical bog once you go wot. emulsion is f16. improved quite a bit once pump had been 50. was 237 horses and 227 lb ft with the above jetting. currently waiting for new jets. will try next the following : choke 36 mains 150 ac 200 idle 60f9 bleeds 0 emulsion f15 or f2 pump 55 or upwards Quote Link to comment Share on other sites More sharing options...
turbeau Posted December 31, 2014 Share Posted December 31, 2014 good stuff from everybody on here. Today I went from 34 chokes, 150 main, 180 AC, 50F9 idles, F11 ET to 30 choke, 120 m, 180 AC, 50F9, F11 ET With the initial set up the car idled at 10.5, cruise between 12-13 and WOT about 13 afr. Tip in from any rev range would spike way lean to 19+ afrs causing stumble, then linear power to 6k rpm (the highest my wimpiness would go) I switched to the 30 choke after reading through datsungarage site and I liked the way he described the new drive-ability of the 30s. Now it idles at 11.25, cruise 13, WOT 13. There is still a small stumble, about .5 sec when tipping in, then full power. It takes off cleanly and stays linear straight through the transition. I thought the car would feel slower but it felt the same, just easier to drive. The afr's were more stable and the car was more predictable to drive. Stock L28 Quote Link to comment Share on other sites More sharing options...
steve260z Posted December 31, 2014 Share Posted December 31, 2014 I'm still tuning the webers...Have you guys ever noticed the AFR changes with ignition timing? Getting my timing up to 32 and now its running leaner. Quote Link to comment Share on other sites More sharing options...
Lazeum Posted January 5, 2015 Share Posted January 5, 2015 (edited) I did see a difference at the time where my engine was pinging. Timing change to avoid ping definitely made a difference. Now, I've got a distributorless ignition I can change timing on the fly. I've got some lean AFR conditions at high rpm so I've done some tests. I have not seen any difference in AFR reading with engine running in proper conditions (no ping) So to answer your question: - Engine running properly, Timing does not interfere much with AFR - Engine running poorly, timing could have significative impact. Edited January 7, 2015 by Lazeum Quote Link to comment Share on other sites More sharing options...
steve260z Posted January 6, 2015 Share Posted January 6, 2015 Yes, I agree. So, I got the Carb synco gauge. I'm getting readings between 5 and 7 between the carbs and unfortunately within 1 carb... How close is acceptable? Obviously identical is the goal. Thanks Quote Link to comment Share on other sites More sharing options...
bradyzq Posted January 6, 2015 Share Posted January 6, 2015 Have you adjusted your valves? You may have effectively different cam profiles for each cylinder if your valves are not well adjusted. Quote Link to comment Share on other sites More sharing options...
steve260z Posted January 7, 2015 Share Posted January 7, 2015 Have you adjusted your valves? You may have effectively different cam profiles for each cylinder if your valves are not well adjusted. Good point. I'll check Quote Link to comment Share on other sites More sharing options...
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