80TexasC3

Does the air/fuel ratio look right for this dyno run? Should the engine run any leaner or is it optimized? There are currently 96 jets in the secondarys.

Thanks for the input in advance...

Ed

MotorHead

I would have thought it would make more power with the blue A/F line.

It seems to make alot more power running leaner ?

What did they do to the carb in between the blue and red runs ?

80TexasC3

Combo of timing, distributor spring rate change and primary jet adjustments. I don't think anything changed on the secondarys as the gasket was stuck and came apart when I took the secondary bowl off.

MotorHead

Methinks someone knows what they are doing at that dyno shop. Leave it alone. 96 in the secondary does sound pretty big but if it works...

Bullshark

Ed. Looks to me like the higher power run was with the higher A/F reading. Looks pretty close to what I have read carburetors should be though.

Even though engines will run anywhere between 5 and 25 A/F, the usual target values for an un-supercharged carbureted engine are a fairly narrow range (Figure 1). A/F is about 12.5 for the WOT and 14.0-15.5 at part-throttle cruise. An intermediate value of about 13.5-14.0 is usually used for mid-range power (non-WOT acceleration).



Bullshark

SBCGENII

You should be the richest at peak tourque which your not in fact the opposet. 14.5~14.7 is good for going down the highway but not at wot you shuold look for a 12.5 ~13 at wot and your car still may like that alittle + - of that

Gordonm

Here is my dyno run. As you can see the two lines that are very flat made the most power. The blue line at the end you can see jumps up. The gauge fell out of the pipe. It should remain flat throughout the run.

80TexasC3

I appreciate the input everyone... so would you leave the 96s in the secondarys or go with a 95 or 94 to tweek the A/F down a little.

Budman68

Ed, Lets put a Holley FI unit on that beast of yours. Check out Zwedes when you get a chance, he's just down the road from you. You can tune by laptop and the seat of your pants.

ajrothm

I would leave it bro....13.5-1 is just a touch lean but nothing thats gonna hurt anything. Ideally 12.8-13.0-1 is what you want but leaner engine will always show more power on a dyno(to a degree, anything leaner then 13.5 or 13.8 will start losing power)

I think you got it tuned pretty well. I mean you could go up a jet size or two on the secondaries but nothing I would do immediately, especially withouth re-dynoing.


What engine and tranny you running? Those are some good numbers.

SBCGENII

You should also keep in mind that you will run leaner on the street than if you where on a dyno jet.

Bullshark

Why is that? Do they control the air flow?

80TexasC3

Hey Budman... long time no talk... Isn't it about time for the AER show?

I have thought about the Holley FI...need to get with Zwede and check it out...he's in Plano..right?

80TexasC3

Thanks... original L48 stroked 383. Flat Top 11.1:1, P&P'ed Edelbrock RPM heads, XR274, Air Gap, etc... Keisler TKO 5 speed.