Slightly rich condition

[72 Deuce]

Greetings All,
Since installing a O2 sensor on the 72 Deuce I'm just a tad rich (11.5:1) at part throttle and in light cruise mode (35-65 mph). I'm confident that my jetting is correct by the O2 readings and the plugs read a nice cocoa brown. The car actually runs so good that I'm hesitant to make any further changes BUT!!! I'm thinking that the richness is a result of the idle circut flow @ part throttle and my thoughts are to place a .010 - .020 piece of wire in the idle feed restrictors to decrease they're area. I read several articles on part throttle richness with holleys and that seems to be the common cure. I just thought I would put it out on the table and get all of your thoughts. Like I said I almost don't want to mess with a good thing but I would like to get that last once of horsepower.

Any and all replys will be gratefully accepted unless they involve the use of explosives as a means to the cure. (hehehehe)

[MostMint]

Help me out of the dark ages please. I have not heard of this technique - maybe I am missing out on something.

If I were rich I would just change the jetting one size leaner. Seems that would be a lot easier than putting a wire in the idle circuit. Unless that idle circuit shuts off at WOT I can't see the difference.

By my math it seems the cross area of a .010" diameter wire would be a slightly smaller restriction than a jet size change.

On a more philosphical note - why do you care about part throttle? What is your mixture at wide open?

If all else fails, forget the explosives - you need a hemi

[72 Deuce]

To answer to the second part of your question first; the reason I care about part throttle is because the car mainly is street driven with only one or two trips to the strip each year (wish it were more). At part throttle in a 3200 pound car on level ground moving @ 35mph only takes about 20 horsepower to sustain that speed. At that throttle opening jet flow is minamal but still does flow but the bulk of the fuel flow is actually through the idle circut. As throttle position increases so does the air flow through the venture area causing more demand for flow from the jets. This does not occur in a linear fashion though. In my application, which is a tunnel rammaed 355 with two 450 holleys, part throttle is extremely sensitive to any changes. Remember there are two separate circuts in a holley idle circut, the idle circut (throttle blades closed) and the transition circut thottle blades open. By reducing the orrifice size with a wire you need to readjust the mixture screws for the idle circut but once the transition slot is exposed the reduced volume from the wire will limit the flow out of the transition slot effectively down jetting part throttle without affecting the main jet at wide open throttle. My WOT is at 12.7:1 which is just about perfect for a carb. car.

Sorry to be so long winded with my answer but I get carried away sometimes

As for the HEMI, I would have to choose the TNT. I can't stand Crysler. I was a mechanic during the Lee Iacoca era, I think that says it all right there. You can draw your own conclusions. (hehe)

[Fred32v]

Word on the street is that the Deuce is a pretty sweet ride, how about a
picture. I love the idea of two 450's over a single 850 or 1000, just for
the looks, if it works as well or better, great! Are they linked straight or
progressive? I put dual quads on a 64 Catalina for a fellow and ran the
car on the primaries of the rear carb, opening everything began about 3/4
throttle. Front cylinders were a little lean but it sure improved his
mileage. Maybe two pictures.

[72 Deuce]

I'm going to work on getting some pictuers up. I actually talked to Markss327 today about doing that. As for the carbs they are mounted in-line and are linked one to one, in other words its not a progressive set up. As stated earlier, I've been working on the combination for about a year and a half and was oh so close to giving up on the tunnel ram and putting a single four barrel back on but know I'm glad I perciviered. The car runs really well. Its kinda tempermental when it comes to cold starting but once theres a little heat in the manifold it runs fine. As for the tunnel ram myths about having no low end torque, well they are just myths. This car pulls out of the hole harder now than it ever has before and 40 mph burn outs are just sick. Take my word for it, it a blast to drive.

Hey, can any readers out there tell me how to post a photo?

[MostMint]

You are optimizing to a level of detail beyond where I typically go. I think your solution will get you where you want to go.

What is your mixture at idle?

I had an 8-pack on a 305 for a long time, and it really liked it once I got it dialed in. I had it on my 327 for a while but the carbs were too small. I think there is definitely some value in multiple carbs, particularly when you are wide open and intake velocity is still low.