Well, I just got back from having my car dynoed. Figures came back about what I was expecting for well used engine. 200k+ miles, a few bad valve seals, rings on their way out, etc. Put it this way, during a full day of autocrossing I use a little more than a quart of oil!

Anyway, I had the air/fuel mixture tested at the sametime. In the meat of my power, the ratio is running rich. Perfect stachiometry (sp?) should be about 14.1. I was told I should be running mid to high 13's running in the power. I'm running low to mid 11's. Basically I'm rich throughout the powerband. I leaned the mixture half a turn on the SU's for the second run, which helped down low, but it still ran almost the same at peak power.

The suggestion has come up to locating a different profile of jet needle. So I'm asking this: Can anybody look at the dyno sheet and tell me if this sounds correct? Have you had this done and seen something familiar? Anybody know where to locate a leaner needle? What about the SM needles I have heard about?

FWI, The motor is a stock '73 L24, stock '71, 4-screw SU's running a stock airbox and filter, 6-2 MSA headers and 2-1/4" exhaust to a Turbo muffler.

I know I could probably lean the mixture nuts out a bit more, but I'm afraid that will lean the low-end too much. Any suggestions?

Check out the dyno sheet here: Dyno Run

Kmack,

Leaning the carbs more will not hurt the engine. It may hurt the throttle response on the bottom end though. What can hurt the engine is a lean condition on the top end, and it looks like your plenty rich up there. If you would like to do some testing, I have some SM needles I'm not using at the moment. If they work for you, buy some and then just send mine back. If they dont work, your not out anything. Contact me directly at:

fly.fred@verizon.net

Ken, Use the SM's!

I'd love to see the run after their installation.

Ha! Aint that something? I'll bet the dyno time in'nt cheap, but I'll gladly vollenteer you to pay for info I want!

Phred, Thanks...I'll get in touch with you by email.

Victor, you're right. The runs aren't cheap, but I worked a hell of a deal for the 4 I got yesterday! I'm in charge of Events for our Z club and I set up a dyno day for the club. What would have normally been $45/run was knocked down to $20/run!

Now I'm starting the stages of putting my rebuilt, original motor back in the car. I will deal with the needle issue at that same time. Thanks for the input guys.

Phred, Thanks...I'll get in touch with you by email.

Victor, you're right. The runs aren't cheap, but I worked a hell of a deal for the 4 I got yesterday! I'm in charge of Events for our Z club and I set up a dyno day for the club. What would have normally been $45/run was knocked down to $20/run!

Now I'm starting the stages of putting my rebuilt, original motor back in the car. I will deal with the needle issue at that same time. Thanks for the input guys.

So how much boost were you running at that AFR?

Seriously, my FJ20ET runs leaner than that at full noise....

Less fuel is required, mid 13's will give you more power.

Having said that, were these runs done with the PCV & valve breather disconnected?

On a tired engine you will see a noticble difference in mixtures if you remove all the blowby....

PCV and Valve breather were both connected at the time of the runs.