Aggressor Mileage Preliminary Stats

[Aggressor]

Mileage is a bit better than I anticipated. Low speed cruising for 22 miles to get ice cream cones with Sharon on a nice Summer evening used 2.2 gallons of 93 octane gasoline.

10 Miles per Gallon in light cruise mode.

On the other hand, working through the minor ignition and fuel related remaining issues has cost 6 1/2 gallons idling in the drive for short sessions with a few short test jaunts.
The short stabs on the accelerator really suck up major fuel.


- Geary

[ralphscott]

Geary, I routinely get 12 miles per gallon (average over 5000 miles)when I drive Lil'Cobra I have tracked the fuel useage at each fill-up since I built. Being that it is such a light car it does not take much to push it along. I think I will be down sizing from my 750 carb to a 650 and changing out my cam from radical to mild. It will be interesting to see the difference...

Ralph

[pbrown]

Has anyone used a wideband O2 meter to dial in their carb? I know of a 69 stroked Hemi Charger with dual carbs that can get 18MPG on the highway.

The carb on my 331 Stroker was cruising at about 10:1 AFR right out of the box. I reduced the IFRs and squared off the IABs and have the cruise AFR right at 14.8:1. The throttle is much more crisp as well.

[Aggressor]

Good call Patrick. A wideband is necessary at this point. Another issue is timing. This engine just seems to do better with much more timing. I'm currently locked down to 32 degrees total while I sort out the many variables associated with raw vintage 60's blowthrough technology. I don't want a major meltdown. I seem to have the primarys, power valves, accelerator pumps, and squirters about right, but cracking the secondaries is still a bit rough. I could stop adjusting now as I don't have a concept of ever using the secondaries. I have experienced a ride at partial throttle on primaries alone that was simply mind-bending. I did not have a concept of straightline acceleration that was that severe.

Do that first thing in the morning and it'll give ya a whole new outlook on the day.

-Geary

[Naumoff]

12 mpg highway with my beast. 2 600cfm Holleys

I want to dyno tune it once I find a guy that I feel comfortable with.

Geary, I think you just need a bigger fuel tank.
When can I come up and visit you so I can get a ride?

[RJacobsen]

I don't have a concept of ever using the secondaries. I have experienced a ride at partial throttle on primaries alone that was simply mind-bending. I did not have a concept of straightline acceleration that was that severe.



-Geary

Sounds like some insight on why Cosby took his back.

[Justin Upchurch]

Patrick,

Funny you mentioned the Wideband, I just prchased one. Now, I have to put the bungs in my headers and wire it in. I had read an article in a Chevy Magazine about a 406 stroker going from 12 to 21 MPG w/ 3.73 gears doing exactly what you just said, so I figured I would give it a go. Any tips?

Justin

[Naumoff]

Patrick,

Funny you mentioned the Wideband, I just prchased one. Now, I have to put the bungs in my headers and wire it in. I had read an article in a Chevy Magazine about a 406 stroker going from 12 to 21 MPG w/ 3.73 gears doing exactly what you just said, so I figured I would give it a go. Any tips?

Justin

Yea, stop reading a chebby magazine.

[pbrown]

Be carefull. Is that is the infamous Chevy High Performance article? If so, don't do anything they say. It's a good way to destroy an engine.

[Justin Upchurch]

I think that is the one. What did they say that is bad or cause engine damage?

[pbrown]

They were making wild guesses as to jet settings and hoping it would work. Going to a .020 IFR was risky and dangerous. The proper way to tune a carb is to base line the carb as is, determine what you need, and then to make small incremental changes to sneak up on the proper tune. Make changes one pin size at a time. Start with the idle, then cruise, then main jets, then power valve.

I typically start by drilling and tapping the main body IAB and HSAB with 10-32 and 6-32 brass set screws. The drill and tap the metering blocks for 6-32 IFRs, E-holes, and PVCRs. Use 3/16" brass set screws and drill the size hole you want in them to create the tune you need.