408 tuning with a Wideband sensor

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I guess I'll soon find out. The carb definitely looks like it means business now.

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Drove the Dart to work after lunch today. Seems to be running about the same which is what I expected. It's currently setup with all the Jets that came with the Proform body. As you can see she's very rich while cruising. After work I'm going to adjust the idle mixture screws to see if the idle will lean out with this new body. Then I'm going to enlarge the idle air bleeds .003-.006 to see how that effects it.

Idle = 13.6 - 14.0
40mph cruise 1700RPM 12.0 - 12.5
50mph cruise 2200RPM 12.0 - 12.5
60mph cruise 2600RPM 12.2 - 12.6
70mph cruise 3000RPM 12.4 - 12.8
80mph cruise 3400RPM 12.7 - 13.0
 
Increased the idle air bleeds by .003. It was difficult to do the same cruise tests as above due to rush hour traffic but I managed to get some info. I couldn't get above 60mph this time. Up to 50mph the curve definately leaned out some but above 50 it richened up pretty quickly. I wonder if the mains are starting to contribute earlier now?

Idle 14.0 - 14.3
40 mph 13.0 - 13.5
50 mph 13.0 - 13.5
60 mph 12.0 - 12.5
 
Looks like the mains are activating around 2500 or so.

You may try another .0015-.002 in IAB to get the cruise a bit leaner.

See how that works and then adjust the mains. Probably going to need a smaller main jet.

Next step would be to see how PVCR sizing is working out.
 
Great information. I will be attempting the same thing here very soon. Mine is a lil stinky at idle right now so it needs some tweaking. I will install the Wide Band on Saturday and start messing with it. I think you are really close to nailing yours!
 
Interesting graph. Since it's a nice cool night out and traffic is minimal, I figured that some more tuning was in order. I drove it to work and the last numbers I posted were pretty accurate. Anything above 50mph went rich to mid 12s. I enlarged the air bleeds another .002 for a total of .005. Doesn't seem like much but it's a 12.5% increase in area from the original size. I had to richen up the idle screws after this change because the idle was getting into the 15s. Slight adjustment and it's right in the mid 14s. Pretty much any cruising situation below 50mph yeilds AFRs in the low to mid 14's now. Time to move on to the main jets. Here's a little video at idle 1000RPM. Sorry for the horrible sound. Not sure why it came out that way.

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Cool.

Set the idle where the engine likes it. Not necessarily to a number. A vacuum gauge might come in handy for this. See where it pulls max vacuum at leanest point.

Work on the mains, maybe step down two sizes and try a drive. I wouldn't mess with the main air bleed until you get the main jet size in range.

Nice deal, fuel mileage will go up quite a bit... not that it's the reason we do this stuff!
 
I know i'm learning a lot!! waiting to start my own wideband thread to see if I can just figure it out with all the info in this one :) good job!
 
Always loved those tuning tools. This is great information for people who have the ability to adjust their carburetor.
 
Swapped out the 72 mains that came with the Proform body for 70s after work today. I probably won't test it out until my drive to Escondido to meet up with Mad Dart tomorrow. I also changed the plugs because they were pretty nasty from running so rich up until now. Once the main jets are dialed in I will probably need to richen up the PV circuit to keep it from going lean under power. Maybe I'll get lucky and it will be good as is. (yeah right)

I'll gladly give you a hand with your's, Louis. After this I should have plenty of spare Holley parts laying around.
 
Drove the car to work after lunch today. It's probably about 15 degrees warmer than the last time I tested it. The idle and transition definitely got richer with the warmer weather. Here's what I saw on the meter

Idle 13.7-14.0
40mph 13.0-13.5
50mph 13.0-13.5
60mph 13.0-13.5
70mph 13.7-14.2

Seems like the transition is still rich. I put new plugs in before this drive. I put about 7 miles on them most of which were just cruising under light throttle between 50-70mph. Plug looks lean to me but I have little experience reading them. I also adjusted the valves tonight for the first time since break in. I'm happy to report that after 600 miles they haven't moved a bit. I heard that Hughes made great rockers and now I'm a believer.

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On the ride home tonight when it was cooler outside, the 40-60mph went back to high 13's low 14's. I think I'll leave it there so it doesn't get too lean on chilly San Diego nights. I did notice it gets a little lean under light acceleration and then goes to mid 12's once the PV opens. A more aggressive pump cam should fix this right? It's currently the stock pink one on the #2 setting. I could move it to #1 which should help some I think. I may order a a blue cam to try as well. Is it recommended to change the cam on the secondarys to the same one?
 
If I remember how to read plugs correctly, isn't the burn on the tip suppose to be in the middle of the bend or else showing like yours means too much timing? And yes those look really lean to me, but this is just me.
 
The timing is set at 32 total right now. I verified that the timing marks are correct again tonight while adjusting the valves. I used the piston stop method so I know it's right. If it's lean then the wideband isn't reading correctly.
 
Loosenutz said:
The timing is set at 32 total right now. I verified that the timing marks are correct again tonight while adjusting the valves. I used the piston stop method so I know it's right. If it's lean then the wideband isn't reading correctly.
Click to expand...

Yeah those plugs look lean to me too. They sure are burning very clean.
 
Did a little research and I may need one step colder plug. That should move the color on the ground strap closer to the bend. These are NGK #7373
 
Loosenutz,still have 10% bushings for sale? I'll take 2 if you do.How much and where do I mail the cashiers check? THX, Bad 6T4
 
I've been reading some articles and it appears that i need a colder plug. Anyone know the next step colder from an FR5?
 
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