Author Topic: MPG, Part 2  (Read 21992 times)

Offline Stewart G Griffin

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MPG, Part 2
« on: August 27, 2016, 12:07:09 PM »
320.6 miles / 17.010 gallons = 18.85 mpg
$2.199 per gallon regular at exxon,  $37.40 to fillup

Now that's more like it.  Not all highway miles either.   i still think there is plenty of room for carb tweeking.  Runs ok though.

New setup:
GM reman 4.3 v-6  LB4  roller lifters, 9:1 compression
Jeg's reman quadrajet #15805
TH-350C trans
2.56 rear gear
235/75-15  Hankook Optimo 727's
Single stock exhaust---stock exhaust Y then rest of exhaust cobbled together with flexpipe and stock type muffler.

Offline Irish_Alley

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Re: MPG, Part 2
« Reply #1 on: August 27, 2016, 01:13:16 PM »
do you have a fan on it this time?
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Offline Stewart G Griffin

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Re: MPG, Part 2
« Reply #2 on: August 27, 2016, 05:40:09 PM »
Yes, definitely----a 14" Spal electric.
« Last Edit: August 28, 2016, 04:28:07 PM by Stewart G Griffin »

Offline redhot1.4

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Re: MPG, Part 2
« Reply #3 on: August 28, 2016, 05:46:29 PM »
My goal is to get my 78 to at least 16mpg.im currently best at 11 mpg. .. Is it possible I have a 350 with a th350 1,2&drive lol
My next upgrade is electric fans

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Offline Stewart G Griffin

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Re: MPG, Part 2
« Reply #4 on: August 28, 2016, 06:48:52 PM »
My goal is to get my 78 to at least 16mpg.im currently best at 11 mpg. .. Is it possible I have a 350 with a th350 1,2&drive lol
My next upgrade is electric fans

Sent from my SAMSUNG-SM-G870A using Tapatalk

i think it's possible, but tell us more.   Also, i don't think electric fans are going to make that much a difference if any, UNLESS you have a fixed fan.   The only reason why i went with electric was to save space and it's not easy to find a shroud for my application.
« Last Edit: September 22, 2016, 08:41:32 PM by Stewart G Griffin »

Offline redhot1.4

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Re: MPG, Part 2
« Reply #5 on: August 28, 2016, 06:51:43 PM »
Plain 350. With the new eps edelbrock performer intake manifold and new 600cfm edelbrock carburetor headers dual exhaust

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Offline Stewart G Griffin

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Re: MPG, Part 2
« Reply #6 on: September 06, 2016, 09:49:55 PM »
Plain 350. With the new eps edelbrock performer intake manifold and new 600cfm edelbrock carburetor headers dual exhaust

Sent from my SAMSUNG-SM-G870A using Tapatalk

What differential gear do you have?


275.7 miles / 17.945 gallons = 15.36 mpg
$2.119 per gallon regular at Shell, $38.03 to fillup


It turns out the choke was not adjusted properly as i had previously thought;  It would get stuck on low-mid step for too long and not go down to curb idle for a good 10-15 mins.   i did not really notice this for the previous tankful because it was mostly highway driving.

Also my tires were pretty low.  My other inflator broke, so i got another one.

So hopefully, the next tank will be better.

Offline redhot1.4

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Re: MPG, Part 2
« Reply #7 on: September 06, 2016, 10:04:15 PM »
Plain 350. With the new eps edelbrock performer intake manifold and new 600cfm edelbrock carburetor headers dual exhaust

Sent from my SAMSUNG-SM-G870A using Tapatalk

What differential gear do you have?


275.7 miles / 17.945 gallons = 15.36 mpg
$2.119 per gallon regular at Shell, $38.03 to fillup


It turns out the choke was not adjusted properly as i had previously thought;  It would get stuck on low-mid step for too long and not go down to curb idle for a good 10-15 mins.   i did not really notice this for the previous tankful because it was mostly highway driving.

Also my tires were pretty low.  My other inflator broke, so i got another one.

So hopefully, the next tank will be better.
Gears I don't really know.  I'm running a 285 75 16 tires.  It's a tall tire. I wanna say at 26 2700rpm I'm going 70mph
I was trying to up the rear end with a tall tire. I'm driving 56 miles round trip on the old truck all highway with a total of 3 stop signs and 2 red lights total.

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Offline Stewart G Griffin

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Re: MPG, Part 2
« Reply #8 on: September 13, 2016, 07:51:58 PM »
322.6 miles / 18.232 gallons = 17.69 mpg
$2.559 per gallon v-tech (premium) at shell.  $46.66 to fillup


i accidentally pushed the v-tec (premium) button at the pump because i'm not use to filling up at Shell.  i normally get regular.


Lots of idling this time;  The traffic situation around here just is not working out anymore.  :(

Got the choke adjusted right.  Engine runs better than ever.

« Last Edit: September 13, 2016, 08:01:50 PM by Stewart G Griffin »

Offline zieg85

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Re: MPG, Part 2
« Reply #9 on: September 13, 2016, 10:21:11 PM »
322.6 miles / 18.232 gallons = 17.69 mpg


not to shabby for a bunch of slow traffic
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 3.21 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline zieg85

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Re: MPG, Part 2
« Reply #10 on: September 13, 2016, 10:24:07 PM »
If you ever need a trans go to a 700R4.  1st. gear would be easier to get the truck moving requiring less throttle.  OD may never be needed unless you hit 85
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 3.21 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
https://www.facebook.com/groups/248658382003506/

Offline LTZ C20

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Re: MPG, Part 2
« Reply #11 on: September 13, 2016, 10:36:11 PM »
If you ever need a trans go to a 700R4.  1st. gear would be easier to get the truck moving requiring less throttle.  OD may never be needed unless you hit 85
85! With a 700, you can go 35 in OD, you can go 40, 45 in OD and lock up. Some even go into lock up in 3rd.
LTZ Cheyenne C20

Offline zieg85

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Re: MPG, Part 2
« Reply #12 on: September 13, 2016, 10:44:25 PM »
If you ever need a trans go to a 700R4.  1st. gear would be easier to get the truck moving requiring less throttle.  OD may never be needed unless you hit 85
85! With a 700, you can go 35 in OD, you can go 40, 45 in OD and lock up. Some even go into lock up in 3rd.

He has a 2.56 rear.  Final drive would be 1.87... probably idle down the road at 45
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 3.21 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
https://www.facebook.com/groups/248658382003506/

Offline LTZ C20

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Re: MPG, Part 2
« Reply #13 on: September 13, 2016, 10:52:21 PM »
If you ever need a trans go to a 700R4.  1st. gear would be easier to get the truck moving requiring less throttle.  OD may never be needed unless you hit 85
85! With a 700, you can go 35 in OD, you can go 40, 45 in OD and lock up. Some even go into lock up in 3rd.

He has a 2.56 rear.  Final drive would be 1.87... probably idle down the road at 45
Oh what a drag. In my opinion 3.73 and 4.10 gears are the only 2 worth using, they are the only 2 GM still puts in new trucks.
LTZ Cheyenne C20

Offline Stewart G Griffin

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Re: MPG, Part 2
« Reply #14 on: September 22, 2016, 08:46:16 PM »
326.3 miles / 16.736 gallons = 19.49 mpg
$2.259 per gallon regular at Exxon,  $37.81 to fillup

Even though there was much less idling this time, this might not be super accurate because i filled up at a different station---the previous two times was Shell and i normally use EXxon.   The pumps at shell are much slower and may allow more fuel to be pumped into the tank?

However, i do sense things are improving overall;  The engine continues to run smoother---i think it is still breaking in more.