Datsun Roadster Forum-311s.org

as a update the new ADQ needles are working great! I just had some time to install them and get the car running. i have set the needle out .013 from the piston. AFR is around 12ish. i will go on a drive tomorrow and do some more tuning based off WOT and partial throttle with the wideband. so stoked as the car is running so much better.

Glad you like them.

Ok so idle is at 12 AFR. Cruising is at 14 flat. When I go WOT it dips into 12ish? Does that mean I need lighter carb oil? I can't figure it out

Do you get a stumble on acceleration? If not you can try a little thinner oil. As I recall you want to be richer when accelerating. You might try setting the needles out just a little more to lean the idle.

I have the needls out .022 will try .026 tonight. I will also do thinner oil. I am not stumbling on acceleration.

Mochi wrote: Sun Jun 05, 2022 8:24 am I have the needls out .022 will try .026 tonight. I will also do thinner oil. I am not stumbling on acceleration.

I’m not sure I quite understand. So the car runs fine now, but you’re NOT happy with the 12:1 A/F mixture at WOT? Why exactly is that?

14 cruise and 12 WOT is pretty much dead on AFR targets. Idle is a tad rich at 12, but it sounds like you've got it pretty dialed in to me.
Are there driveability issues, or are you just looking for different numbers? Those numbers are impressive.

Mochi, I agree with everyone else on your AFR numbers, they sound almost perfect to me....can I ask what kind of / brand / model AFR gauge setup are you using ?.....and what damper oil are you using with those numbers ?
Thanks, Mike

Yep, one more saying the AF ratios are pretty darn close. You probably are giving up a little bit of fuel economy but the engine is safer. If you could lean it out a point (13 idle, 15 cruise, 13 WOT) you would be golden! Very impressive.

Bwk2000 wrote: Sun Jun 05, 2022 8:51 am

Mochi wrote: Sun Jun 05, 2022 8:24 am I have the needls out .022 will try .026 tonight. I will also do thinner oil. I am not stumbling on acceleration.

I’m not sure I quite understand. So the car runs fine now, but you’re NOT happy with the 12:1 A/F mixture at WOT? Why exactly is that?

Kinda looking at generic dyno runs and topics on AFR. 13 AFR seams safe while producing more power then a richer setup. I have not dynoed the engine and probably won't. 13 seams the most logical choice to shoot for without having a dyno to check power numbers.

23yrRebuild wrote: Sun Jun 05, 2022 5:08 pm Mochi, I agree with everyone else on your AFR numbers, they sound almost perfect to me....can I ask what kind of / brand / model AFR gauge setup are you using ?.....and what damper oil are you using with those numbers ?
Thanks, Mike

I am using a pe wideband setup with their supplied bosch sensor. Probably will need to clean/change sensor as the idle probably dirtied the sensor. It's a 30 weight motor oil that I picked up at a local auto store. Did a quick search and hopefully I did enough research, but I don't think I need a special su carb oil if you wanted to change how you wanted the carb react to acceleration. My AFR spiked previously without stumbling but it alarmed me to lessen the spike. That is why I changed oil weight.

13, yep. It can take a moment for your wideband to give an accurate number with sharp hits of the throttle, so you are wise to feel how the car responds and listen for ping. An SU has no enrichment curcuits of course, so it's all in keeping that piston from slamming up too fast eh?