Triple Stromberg Needle Size Issues

[Trick6]

My three Strombergs were prepared by Jeff at PalTech and arrived with B1AR needles. The dyno showed these needles to be very rich and HP robbing. During the dyno pulls, the AFR reading went from 14.5 at 2000 rpm to 11 at 3200 and remained there to 5200. I tried to lean the mixture by adjusting them out (counter-clock wise) to the point that they were floating in the diaphragms. No major change on the dyno AFR reader. I could not believe that the needle adjustments did nothing but the tail pipe pickup sniffer was used and showed little or no change.

I have since installed the original size B1AF needles. The motor runs much better but the plugs are reading a wee bit lean. Now I can't enrich the mixture because these needles are screwed in full clock wise. I have not returned to the dyno yet. I now have a bung in the exhaust collector ready for a correct AFR reading.

I am preparing for another dyno session but I am wondering what you other triple Stromberg people are using for needles. Any recommendations?

 

[Brosky]

Al,

I have the B1AF in my carbs and they are a little rich at WOT (11.5-11.7), but I haven't played with them since the new engine went in, because I wasn't allowed to run at WOT much. My cruise readings are at 14.7-15.2 so I'm happy with that for now. The head is getting re-torqued tomorrow and I may play around a bit on the weekend.

I started from scratch with mine (last fall after the dyno said I was at 10.0 WOT) and bottomed them out, then came back 3 full turns and ended up 1/2 turn back in from there on each.

I did this after the A/F meter installation and it was much easier to see the differences as I tweaked then in. The problem with the tailpipe sniffer on the stock exhaust is the 90 degree bend in the tailpipe. That can sometimes cause a problem with the readings.

Make sure that your plugs are new and the timing is dead on before you start doing this process.

If you want a spreadsheet that will explain the entire length of the needle in comparison to the B1AR, email me and I'll send it to you.

 

[DNK]

Paul- How did you come up with the proper #'s for cruise?

 

[Trick6]

Paul:
Thanks for the info. It is helpful to know, for a base, that we are using the same needles. I know that we have different heads and exhaust systems which will affect the needle's performance and AFR but the base is the same.

I can't wait to get the A/F meter. It is going to make a huge difference when it comes to tuning. I sent Erik the same question, so if you run into him just tell him that you gave me the info.

I have the Excel spreadsheet of needles. Richard sent it to me some time ago when I wrote him about the needle question. It is a real neat spreadsheet. I have also spoken to Joe and this is going to be a trial and error process facilitated by the A/F meter to minimize taking wrong directions.

I set the timing in a strange way; advance until it pings and back a degree or two until the pinging goes stops. The plug read tells me that my timing is right on the mark.

Thanks again for the needle size.

I know you can't wait to do the WOT thing this week. Maybe we can hook up to do a dyno day.

 

[swift6]

I can't remember right now which needles I have in my triple Stromberg set up but I have a different challenge than most of you. It's called altitude. :wink: I know the B1AF's were way too rich for me, they are on the edge with the stock dual Strombergs at this altitude too though. Joe Curto helped me pick a different needle and the driveability is better, but I haven't been able to get it back to the dyno yet and I have yet to install a real time A/F meter.

 

[Brosky]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Paul- How did you come up with the proper #'s for cruise?[/QUOTE]

Stromberg manual.

 

[tom628]

Al, I'm using the B1AF needles also. No dyno runs or A/F data, but it pulls strong thru the whole rpm range, and, after some tweaking , the plugs look good.

Tom
3 ZS
Isky road cam
head shaved (?amt?)
headers, Monza
Crane XR700

 

[DNK]

Ok My answer to Paul's response yesterday ended up in Cyber space.
My understanding that those #'s came about because they were the best #'s for cat. converters to work efficiently . I always wondered what the correct readings for non cat. cars should be.

 

[Trick6]

I am in the process of selecting an AFR gauge/monitor in preparation of returning to the dyno. I will leave the stock B1AF's in, adjusted to full rich, but take the B1AR's with me. I know that the R's are too rich but I am much smarter now, and will have the proper bung for AFR dyno connection and reading.

I will share the dyno sheet with all.

 

[Brosky]

Don,

My manual was written for the 69-74 TR6's and there were no Catalytic convertors on any of them.

My tailpipe(s) is a nice brown/grayish color and the plugs all look good as well.