Woah, Woah! Brosky, I need a needle!

[LastDeadLast]

Paul,

The tale-tale air/fuel gauge is telling me that I'm running pig rich at 11.5 at full throttle @4-5000rpm.

Where did you get those "leaner" needles for your triple carbs and what did you get?

Thanks!

 

[Brosky]

Shannon,

I never needed to change my needles. I readjusted each carb, one by one, from the bottomed out position of the needle to where it stunk up the garage from being too lean. Then I got them set just right and I'm at about 12.0 - 12.2 at WOT 4,000 RPM and up.

I had to play around with them a bit, but it was fun and worth the exercise. I spoke to Joe Curto in NY and several guys at the British Legends weekend who are well known ZS-CD tuners in this area. They all felt that I had them about as good as they could get them and to leave well enough alone. I did not call Jeff Palya at the time, because he was not working when I was doing the job.

Erik, who does the work for me also felt that the car was set well at those numbers and he would know, because he's driven it many times. He didn't feel that he could get them any better, even by swapping needles, because you can give yourself a lean condition where you don't want it if you swap.

It sounds like you're just about there, so tweak them a bit. I did send you the spreadsheet for the needle sizes, didn't I? It will show just how subtle or radical the changes in needles can be.

 

[LastDeadLast]

You're correct, you did send me that spreadsheet. I'll go over it. I bought my carbs from Jeff, so maybe I'll shoot him an email to see what he says.

I can't remember, but what A/F rations are you seeing? 11.5 is what I got AFTER leaning the carbs up 3/4 of a turn.

I'll lean mine up as much as possible and see what happens. Kinda neat though. I can definitely tell a power difference just in the needle tuning that I've been doing.

At this point, I think the only thing that has kept my plugs from fouling is the hi-po ignition.

Do you know from a full rich position, how many turns I can twist the needles before they fall out?

Thanks,

 

[Brosky]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Do you know from a full rich position, how many turns I can twist the needles before they fall out? [/QUOTE]

Three (3) turns is the magic number for the ZS-CD carbs.

 

[LastDeadLast]

I just set mine to 2-3/4. Are you saying that 3 turns is where it falls out? Or thats where you have your's set?

Again, many thanks.

 

[LastDeadLast]

I was wondering why I never had a pinging problem with 10:1 compression.. now I know! /bcforum/images/%%GRAEMLIN_URL%%/hammer.gif

 

[Brosky]

Shannon,

Three (3) is where they are ready to fall out. I know that to be true, but not in a bad way. I did it just to prove it to myself before starting to tweak running engine.

Just for the record, I took mine up and down twice before getting them right. I'm at 2.0 of the way out.

Let it sit and try it again tomorrow. One important thing to do is to clear the excess fuel from the carbs and engine every so many minutes during this process or you will get inaccurate readings.

 

[LastDeadLast]

/bcforum/images/%%GRAEMLIN_URL%%/thankyousign.gif

Thanks for the info. I'm going to try 2-3/4 turns and see what happens. At the very least it's a benchmark.

I need to get the rest of my logging gear installed. Right now, I'm only looking at each side separately with no logging. Once fully installed, I'll be able to log A/F vs. RPM... Now if only I could figure out how to fashion a throttle position sensor... /bcforum/images/%%GRAEMLIN_URL%%/jester.gif

 

[Brosky]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:] Now if only I could figure out how to fashion a throttle position sensor..[/QUOTE]

Where is Alana hiding? I'll bet that he knows exactly how to fashion one of those for you.

 

[davidk]

Here's a picture of the throttle position sensor on my TBI setup. It came from this site:

https://sidedrafttbi.com/CD175tps.htm

 

[LastDeadLast]

David,

Wow thats neat! Thanks!

I'll do some research and get on it.