ZZ4 MPG Challenge II

[gchemist]

Vacationing from July 24-August 2nd. BADBOW is going on its second major trip. The ZZ4 now has 6000 miles since being installed. I may even hit the strip too! It is getting a custom hitch installed for the roll pan. I managed 18.5 MPG out of the ZZ4 after a few adjustments. I'm going to see if I can squeeze 19 and still do 70 MPH!!

Any suggestions for improvements? I'm thinking of backing off on timing to 8-9 degrees. Specs call for 10 BTDC at 800 RPMs. My problem is that my digital tach is not working. It works but I think the ground behind the dash is bad. If I have time, I hope to fix it during this trip.

What ya think?

[westie 666]

OK I'll bite, 19+, but, how do you get accurate milage if your dash aint working?

[gchemist]

The stock speedo and fuel guages work. Speedo gears are matched for tires, rear gears and 700R4. Cruise RPMs ~1950-2000. Digital temp works too.
http://www.geocities.com/abetterchemist/cab.html

Due to my travel distance 480 miles in one direction (~9.5 hours) . I can run full tanks from full to empty. I write down milage and calculate.

[Duro5341]

Originally Posted by gchemist

Due to my travel distance 480 miles in one direction (~9.5 hours) . I can run full tanks from full to empty. I write down milage and calculate.

Finally someone calculating it properly, so many people go by the stupid gas guage. I dunno about you, but mine is no where accurate, just gives me an idea how much gas is in it.

If the spec sheet said 10 deg BTDC, I would keep it there. It's propably spec. for that cam, heads, and intake combo. I wouldn't deveate from it to much.

I put the lucas fuel stabilizer in every tank, it's about $8 a bottle, an will last 8 tank fulls (65L tanks)...I noted 50km more on each tank, and it runs alittle smoother, it just lubes the top end

Duro

[swb85]

Retarding the timing will reduce fuel economy and power output. If anything, get yourself an adjustable vacuum advance can and run as much vacuum advance as you can safely get away with on the grade of fuel you're using. That will net you the best fuel economy.

I think 19-20 is totally realistic out of your setup with properly tuned carb/timing.......I'm getting 16-17 with a 450hp 383 stroker with no overdrive, 70mph @ 2700rpm.

[retselgerg]

sounds crazy but my stock GM crate is getting 19-20 with a bulldog 4speed(with a 308 rear, and a very fine adjusted Qjet)

[gchemist]

I completed my first trip leg. BADBOW managed 299 miles on a fuel tank. I have not filled it up but estimate about 15.5 gallons.
Austin to outskirts of Synder TX!
76131 to 76430 miles = 299 miles = 19.29 MPG.
Wow, I'm pressed myself. It's like the ZZ4 is just breaking in! The previous oil change had half a bottle of Marvel Mystery oil. The oil turned black within a few miles. The engine still had a lot of junk from the previous owner. I'll have one more shot, on my return trip, to go through another tank without city driving or pit stops for visits.

I considered turning one degree down because on a 100 degree day, the motor will ping on accelleration in OD. Pinging is minimal. I don't mind a little. I can just put a little more throttle so it kicks down to accellerate. Until my tach is fixed, I just don't know the accuracy of timing.

[boatpuller]

sounds good to me.enjoy the heck out of it.that's the main thing.