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Re: 25 MPG with a 408 ??? Yup!!
[Re: cogen80]
#500603
10/22/09 12:48 AM
10/22/09 12:48 AM
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Joined: Feb 2009
Posts: 982
W. Sacto CA. USA
phantomx
super stock
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super stock
Joined: Feb 2009
Posts: 982
W. Sacto CA. USA
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I had a 360, O/D 833, and 3.23 gears in my 67 Barracuda. That car FLEW on the freeway, 100 mph @ 3K rpm  Spent most of my commute @ 2200 in the fast lane. Travis..
70 GTX project, orig 440-4, 4 spd, track pack, FC7, stripper/street racer special.
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Re: 25 MPG with a 408 ??? Yup!!
[Re: cogen80]
#500604
10/22/09 07:59 AM
10/22/09 07:59 AM
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Joined: Dec 2004
Posts: 1,061
New Mexico
dmerc
OP
super stock
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OP
super stock
Joined: Dec 2004
Posts: 1,061
New Mexico
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Quote:
damn whats that like a 2.30 gear ratio in OD with those gears and tires?
2.261 to be exact! Just rumbles along at 70 MPH.
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Re: 25 MPG with a 408 ??? Yup!!
[Re: dmerc]
#500605
10/22/09 08:26 AM
10/22/09 08:26 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
Here's the recipe:
Magnum heads with tight quench .030. Bowls opened up. Stock valve job.
Wiesco dished pistons
Mopar Performance M1 Dual plane intake
Roller cam Compcams #20-000-9 506 lift 216 intake 224 exhaust duration.
Mopar orange box. 340 HP manifolds with a TTI 2 1/2 inch exhaust system.
Distributor that I recurved for timing all in at 2000 RPM.
This is a big one: Thermoquad 850 carb. Best carb I've tried and I've tried them all.
700R4 Chevy trany with converter lockup. But any overdrive trans would work.
3.23 8 3/4 rear end
Aluminum radiator with electric fans. Fans don't operate at anything over 40 MPH so you gain at least 1 MPG with that mod.
one question: are you running an adapter for the t-quad on the M1 dual plane, or is it capable of bolting up a spread bore?
some thoughts on the combo, it sounds like a real fun street combo, you could probably get a fair amount more power (~20-25HP & TQ) without sacraficing fuel economy (maybe even help a bit) going to headers.
you're leaving power on the table with the stock valve job in the magnum heads. it's undersized from the factory, and there's gains to be had to opening it and the pushrod pinch up (probably ~40-50HP)....would be interesting to see the power/economy difference with some lightly massaged EQ 318 (hughes "iron ram") heads or RHS heads
from what I've heard the M1 leaves something to be desired as far as performance, that it's essentially no better flow wise than a stock piece. would be interesting to try an LD340 modified to fit the t-quad....that might net you another 15-20HP....
I've thought that comp cam (XR265HR) would make a nice street cam for a small block....it must idle pretty much near stock with 408 cubes under it.
best I've managed so far with my 318 is 18mpg...combo is stock short block, home massaged magnum heads, reground cam by bullet cams, 259/259 adv, 208/208@.050, .316" lobe lift, .506" @ valve, headers, 3" single exhaust, RPM air gap, eddie 1406.
tranny is an A500, rear gears are 3.55, tires are 27" tall...car is a 5th ave, 3950lbs w/o me. I think my carb is what's holding my mileage back now...I haven't done an all highway/freeway trip, I'm guessing it'd hit 20.
Last edited by patrick; 10/22/09 08:30 AM.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: 25 MPG with a 408 ??? Yup!!
[Re: patrick]
#500606
10/22/09 08:51 AM
10/22/09 08:51 AM
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Joined: Dec 2004
Posts: 1,061
New Mexico
dmerc
OP
super stock
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OP
super stock
Joined: Dec 2004
Posts: 1,061
New Mexico
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Quote:
Quote:
Here's the recipe:
Magnum heads with tight quench .030. Bowls opened up. Stock valve job.
Wiesco dished pistons
Mopar Performance M1 Dual plane intake
Roller cam Compcams #20-000-9 506 lift 216 intake 224 exhaust duration.
Mopar orange box. 340 HP manifolds with a TTI 2 1/2 inch exhaust system.
Distributor that I recurved for timing all in at 2000 RPM.
This is a big one: Thermoquad 850 carb. Best carb I've tried and I've tried them all.
700R4 Chevy trany with converter lockup. But any overdrive trans would work.
3.23 8 3/4 rear end
Aluminum radiator with electric fans. Fans don't operate at anything over 40 MPH so you gain at least 1 MPG with that mod.
one question: are you running an adapter for the t-quad on the M1 dual plane, or is it capable of bolting up a spread bore?
some thoughts on the combo, it sounds like a real fun street combo, you could probably get a fair amount more power (~20-25HP & TQ) without sacraficing fuel economy (maybe even help a bit) going to headers.
you're leaving power on the table with the stock valve job in the magnum heads. it's undersized from the factory, and there's gains to be had to opening it and the pushrod pinch up (probably ~40-50HP)....would be interesting to see the power/economy difference with some lightly massaged EQ 318 (hughes "iron ram") heads or RHS heads
from what I've heard the M1 leaves something to be desired as far as performance, that it's essentially no better flow wise than a stock piece. would be interesting to try an LD340 modified to fit the t-quad....that might net you another 15-20HP....
I've thought that comp cam (XR265HR) would make a nice street cam for a small block....it must idle pretty much near stock with 408 cubes under it.
best I've managed so far with my 318 is 18mpg...combo is stock short block, home massaged magnum heads, reground cam by bullet cams, 259/259 adv, 208/208@.050, .316" lobe lift, .506" @ valve, headers, 3" single exhaust, RPM air gap, eddie 1406.
tranny is an A500, rear gears are 3.55, tires are 27" tall...car is a 5th ave, 3950lbs w/o me. I think my carb is what's holding my mileage back now...I haven't done an all highway/freeway trip, I'm guessing it'd hit 20.
Hey Patrick, I do have an adapter on my M1. It's a square bore manifold. I know I left at least 50HP on the table but I wanted a stock idle with some hit to it. I debated having a three angle valve job but just ended up having the bowls hogged out and doing a nice bowl blend. This experiment was to try to make the engine as efficient as possible with high performance as a secondary goal. I know I'll want more power in the future. I have a new crosswinds manifold I might try out. If you are not running a thermoquad I can almost guaranty you'll get 2 to 3 MPG better gas mileage with one. They are just outstanding at atomizing the fuel at small throttle openings.
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Re: 25 MPG with a 408 ??? Yup!!
[Re: dmerc]
#500607
10/22/09 09:02 AM
10/22/09 09:02 AM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Quote:
damn whats that like a 2.30 gear ratio in OD with those gears and tires?
2.261 to be exact! Just rumbles along at 70 MPH.
putting a 2.261 gear in a muscle car that you spent all kinds of $$$ building a 408 storker is like neutering your prize race horse because you want him to live longer.... if you wanted MPG's you could have just rebuilt a 318 and used a 2bbl throttle body. 
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Re: 25 MPG with a 408 ??? Yup!!
[Re: Mr.Yuck]
#500608
10/22/09 09:10 AM
10/22/09 09:10 AM
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Joined: Oct 2009
Posts: 164
Indiana, United Staes, Vevay
LikarockCrusher
member
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member
Joined: Oct 2009
Posts: 164
Indiana, United Staes, Vevay
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Quote:
Quote:
Quote:
damn whats that like a 2.30 gear ratio in OD with those gears and tires?
2.261 to be exact! Just rumbles along at 70 MPH.
putting a 2.261 gear in a muscle car that you spent all kinds of $$$ building a 408 storker is like neutering your prize race horse because you want him to live longer.... if you wanted MPG's you could have just rebuilt a 318 and used a 2bbl throttle body.
I AGREE! My question is what is the Volume Eff.
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Re: 25 MPG with a 408 ??? Yup!!
[Re: LikarockCrusher]
#500609
10/22/09 09:25 AM
10/22/09 09:25 AM
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Joined: Jul 2005
Posts: 3,072
Farmland, IN
Ludington1
master
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master
Joined: Jul 2005
Posts: 3,072
Farmland, IN
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Quote:
Quote:
Quote:
Quote:
damn whats that like a 2.30 gear ratio in OD with those gears and tires?
2.261 to be exact! Just rumbles along at 70 MPH.
putting a 2.261 gear in a muscle car that you spent all kinds of $$$ building a 408 storker is like neutering your prize race horse because you want him to live longer.... if you wanted MPG's you could have just rebuilt a 318 and used a 2bbl throttle body.
I AGREE! My question is what is the Volume Eff.
I think that's just his ratio in OD
Nice build and stats, thanks for sharing!
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Re: 25 MPG with a 408 ??? Yup!!
[Re: dmerc]
#500610
10/22/09 10:48 AM
10/22/09 10:48 AM
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Joined: Nov 2007
Posts: 5,337
the house on the left.
cogen80
master
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master
Joined: Nov 2007
Posts: 5,337
the house on the left.
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Quote:
Quote:
damn whats that like a 2.30 gear ratio in OD with those gears and tires?
2.261 to be exact! Just rumbles along at 70 MPH.
i guess the 408 with a 3.23 is still pretty peppy around town right?
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Re: 25 MPG with a 408 ??? Yup!!
[Re: cogen80]
#500611
10/22/09 11:37 AM
10/22/09 11:37 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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probably, especially considering the 700R4 has a 3.09:1 first gear, so overall first gear is effectively like a 727 with a 4.10.
my setup, with an A500 (2.74 first gear, .69 OD) and 3.55's is like a 727 with 3.91's in first, and a 2.45 rear in OD...
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: 25 MPG with a 408 ??? Yup!!
[Re: patrick]
#500612
10/22/09 11:42 AM
10/22/09 11:42 AM
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Joined: Nov 2007
Posts: 5,337
the house on the left.
cogen80
master
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master
Joined: Nov 2007
Posts: 5,337
the house on the left.
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Quote:
probably, especially considering the 700R4 has a 3.09:1 first gear, so overall first gear is effectively like a 727 with a 4.10.
my setup, with an A500 (2.74 first gear, .69 OD) and 3.55's is like a 727 with 3.91's in first, and a 2.45 rear in OD...
good point. i forgot about that. at first it sounds like a waste until you really look at the trans and gears.. not bad.
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Re: 25 MPG with a 408 ??? Yup!!
[Re: dmerc]
#500613
10/22/09 12:02 PM
10/22/09 12:02 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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Quote:
Hey Patrick, I do have an adapter on my M1. It's a square bore manifold. I know I left at least 50HP on the table but I wanted a stock idle with some hit to it. I debated having a three angle valve job but just ended up having the bowls hogged out and doing a nice bowl blend. This experiment was to try to make the engine as efficient as possible with high performance as a secondary goal. I know I'll want more power in the future. I have a new crosswinds manifold I might try out. If you are not running a thermoquad I can almost guaranty you'll get 2 to 3 MPG better gas mileage with one. They are just outstanding at atomizing the fuel at small throttle openings.
I followed this article by dulcich porting my mag heads....looking at his results, the bowl doesn't look like much of a restriction, the undersized valve job and especially the pushrod pinch seemed to me to make the biggest difference.
one thing with the air gap/crosswind, it's taller than stock (I presume the M1 is a low rise (stock height) intake if you can fit a stock air cleaner with an adapter). right now I have about 1/2" between my stock air cleaner and hood in my M body with an RPM air gap. you will probably be better served with an LD340, as they can be modded to use a spread bore carb without an adapter, and are about the same height as an Air gap (it's essentially the precursor to the eddie RPM manifold).
to all the people questioning "why?" well, some of us like to drive our cars a lot. I pulled my old 360 combo and sold it, it worked very well for what it was, pushing my porky M body to keep up with a 5.7L LX car, but with my existing OD tranny and rear gear could manage a best of 15 MPG in my daily commute (about 60/40 hwy/cty). I built up my roller cammed 318, and on the butt dyno it feels as strong as my old 360 combo, while having 4" more vaccuum at idle (it has a very stockish idle now, which I like), and increasing my mileage 20% (up to 18 in my commute).
power and economy are not mutually exclusive. look at the Z06 vette-- 505HP out of a [Email]218@050[/Email] hydraulic cam, and over 20mpg highway, or my friend's SRT8 300C--high 12's out of a 4200 lb car, that manages ~22mpg highway.
what's available for a t-quad as far as choke options? are they all the well style, or can you find some with an electric choke? I've thought about switching my airgap/600 eddie to an LD340/tquad or qjet combo, figuring I wouldn't lose performance, but perhaps gain economy. of course, I've got about 80% of the parts to convert my car to MPI, just don't have the time to sort it all out.
I think you could help both power and economy with headers. another thought I've had for economy and power was high compression, short timing cam with wide LSA, high flowing heads, and use water injection to suppress detonation.
something like ported RHS magnum heads, flat top pistons, tight quench (would be about 11.5:1), a single pattern cam with maybe 2-4 degrees more intake .050 duration than yours, but ~.540 lift on a 112 or 114 LSA installed at 108,
headers, LD340, and t-quad with water injection....I'd expect it to be in the 470-500 HP range, with a peak just north of 5000 RPM, mondo TORK! mild idle, and something that could squeak out over 20 mpg on a highway trip.
Last edited by patrick; 10/22/09 12:02 PM.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: 25 MPG with a 408 ??? Yup!!
[Re: Mr.Yuck]
#500614
10/22/09 12:03 PM
10/22/09 12:03 PM
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Joined: Dec 2006
Posts: 3,533
Indiana
Fury Fan
master
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master
Joined: Dec 2006
Posts: 3,533
Indiana
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Quote:
why build a 408 to run 13.5? Who care about mpg...make it run right and you might be able to pull a 13.0.
Quote:
putting a 2.261 gear in a muscle car that you spent all kinds of $$$ building a 408 storker is like neutering your prize race horse because you want him to live longer.... if you wanted MPG's you could have just rebuilt a 318 and used a 2bbl throttle body.
Dang, Swingin', why you gotta rain on his parade?  It's his daily driver. The guy built a combo with a good sweetspot he should be congratulated, not ridiculed.
Go put 4.88s in everything you own and poke your fuel tank with an icepick so you can use as much gas as you see fit.
Parts I seek:
driver doorpanel, 65 Sport Fury, prefer black, needs to be 7-8 on 10 scale, might buy set
16" x 6" Dodge truck wheel(s), from early 70s?, takes 9" dogdish - need for a research job so cheaper is better.
69-73 C-body caliper brackets and/or splashields
Send a PM.
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Re: 25 MPG with a 408 ??? Yup!!
[Re: cogen80]
#500615
10/22/09 12:03 PM
10/22/09 12:03 PM
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Joined: Dec 2004
Posts: 1,061
New Mexico
dmerc
OP
super stock
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OP
super stock
Joined: Dec 2004
Posts: 1,061
New Mexico
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Quote:
Quote:
Quote:
damn whats that like a 2.30 gear ratio in OD with those gears and tires?
2.261 to be exact! Just rumbles along at 70 MPH.
i guess the 408 with a 3.23 is still pretty peppy around town right?
Just to put it in perspective I had to put the 275 tires on the rear to keep wheelspin down. First gear was almost useless. Now I can leave the line under control and only have wheel spin part way through 2nd. I don't know why I got the negative comments from some people. Don't they know a transmission has more than one gear? 
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Re: 25 MPG with a 408 ??? Yup!!
[Re: Fury Fan]
#500616
10/22/09 12:14 PM
10/22/09 12:14 PM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Quote:
why build a 408 to run 13.5? Who care about mpg...make it run right and you might be able to pull a 13.0.
Quote:
putting a 2.261 gear in a muscle car that you spent all kinds of $$$ building a 408 storker is like neutering your prize race horse because you want him to live longer.... if you wanted MPG's you could have just rebuilt a 318 and used a 2bbl throttle body.
Dang, Swingin', why you gotta rain on his parade? It's his daily driver. The guy built a combo with a good sweetspot he should be congratulated, not ridiculed.
Go put 4.88s in everything you own and poke your fuel tank with an icepick so you can use as much gas as you see fit.
hahaha no, not to rain but why build a 408 if you want mpg's? go buy a car that gets good gas milage.
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Re: 25 MPG with a 408 ??? Yup!!
[Re: Mr.Yuck]
#500617
10/22/09 12:36 PM
10/22/09 12:36 PM
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Joined: Jan 2003
Posts: 6,816
Alton, IL
Dakota_Don
master
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master
Joined: Jan 2003
Posts: 6,816
Alton, IL
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Quote:
Quote:
Quote:
why build a 408 to run 13.5? Who care about mpg...make it run right and you might be able to pull a 13.0.
Quote:
putting a 2.261 gear in a muscle car that you spent all kinds of $$$ building a 408 storker is like neutering your prize race horse because you want him to live longer.... if you wanted MPG's you could have just rebuilt a 318 and used a 2bbl throttle body.
Dang, Swingin', why you gotta rain on his parade? It's his daily driver. The guy built a combo with a good sweetspot he should be congratulated, not ridiculed.
Go put 4.88s in everything you own and poke your fuel tank with an icepick so you can use as much gas as you see fit.
hahaha no, not to rain but why build a 408 if you want mpg's? go buy a car that gets good gas milage.
a 408 thats gets 25mpg is something to brag about, and i bet there is room for another 1-2 mpg improvement.. esp since it has a carb,
good job
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Re: 25 MPG with a 408 ??? Yup!!
[Re: Dakota_Don]
#500618
10/22/09 12:46 PM
10/22/09 12:46 PM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Quote:
Quote:
Quote:
why build a 408 to run 13.5? Who care about mpg...make it run right and you might be able to pull a 13.0.
Quote:
putting a 2.261 gear in a muscle car that you spent all kinds of $$$ building a 408 storker is like neutering your prize race horse because you want him to live longer.... if you wanted MPG's you could have just rebuilt a 318 and used a 2bbl throttle body.
Dang, Swingin', why you gotta rain on his parade? It's his daily driver. The guy built a combo with a good sweetspot he should be congratulated, not ridiculed.
Go put 4.88s in everything you own and poke your fuel tank with an icepick so you can use as much gas as you see fit.
hahaha no, not to rain but why build a 408 if you want mpg's? go buy a car that gets good gas milage.
a 408 thats gets 25mpg is something to brag about, and i bet there is room for another 1-2 mpg improvement.. esp since it has a carb,
good job
that is good.. I managed 17mpg at 75mph over a 35 mile drive. w/ my 340 swinger 3.55's 727 and with a 750DP carb tuned for max HP. and it ran 13.80 just saying..
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Re: 25 MPG with a 408 ??? Yup!!
[Re: Jerry]
#500620
10/22/09 01:14 PM
10/22/09 01:14 PM
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Joined: Dec 2004
Posts: 1,061
New Mexico
dmerc
OP
super stock
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OP
super stock
Joined: Dec 2004
Posts: 1,061
New Mexico
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Quote:
let me know when your ready to switch over to efi. get a tunnel ram bottom on there with a custom top and some nice atomizing injectors and you could probably see another 2-3 mpg with alot of tuning and a wideband. with the efi you can really dial in what your engine needs, plus you can adjust your timing based on what your engine needs.
Jerry, you don't know how much I'd like to do a FAST EZ fuel injection set up. It would be awesome! It's so darn expensive though. Got any low buck set ups for a buddy? 
I already use a LM-1 for tuning
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