SB Needles to Resolve Lean WOT with SUs

[Jeff G 78]

28 minutes ago, duffman said:

Just participated in a 200 mile drive through some old AZ mining towns yesterday, had a great time! 

I love the roads around Jerome. Were you in that area?

[Duffman]

Not this trip, though I have done that a few times!  We drove through Superior, Winkelman and Globe yesterday, a fun drive!

[Captain Obvious]

9 hours ago, duffman said:

Am going to order the RH needles for comparison purposes, and possibly lean out a few spots in the range.

Yeah, sorry I couldn't help you out with the RH needles. Good luck with the tinkering, and keep us posted!

Short story for the rest of the forum... I went looking for my RH needles that I thought I had and only came up with just ONE instead of two. Not much help there!   

[240260280]

Some work I did a couple of years ago:

 

Edited March 4, 2019 by 240260280

[240260280]

I had some time so I plotted SB & RH

 

Edited March 4, 2019 by 240260280

[german240]

@240260280 I already did this in post #19 ?

 

Edited March 4, 2019 by german240

[240260280]

I'm very proud of you!

[Duffman]

Thanks, Phil, appreciate the comparison of all 4 needle specs, very helpful!

[240260280]

It looks like a little off station one for SM, SB, RH will give a richer idle if needed.

Edited March 4, 2019 by 240260280

[Duffman]

I noticed that.

[Duffman]

I installed a set of RH needles and they ran lean (16 to 17 APR) on WOT on numerous test runs. Went back to SB needles.
There are a few rich spots on the SB needles (cruise is around 13.5), so dropped the needle shoulder down so even with bottom of piston. This kept the WOT numbers on target (13 to 13.5) and the cruise numbers are closer to 14. Will test further, but pleased so far!


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[240260280]

If the idle and cruise are good with the RH then you could taper stations 6 to 14 to make a sweet custom needle!