1975 H70 w 6V53. Mpg? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

greywuuf · 12-07-2018, 03:39 PM

So I have a dream a truck and some time. I know Detroit's are thirsty....but given that I have a "7500" series with a 6V53n that I plan to road trip with. What is my best option for maybe the best mileage ? Currently it is a single speed with a 5 speed and 20" splits....hoping to go 22.5 one piece . Also open to transmission upgrade. I figure a little taller tire and keeping it light are about all I can do to see better fuel consumption. Anyway a small camper shell, lightweight pop-up tent style less than 1000 pounds all loaded up, and not sticking up in the wind. What kind of fuel burn am I looking at ?

Bimus · 12-07-2018, 04:18 PM

I drove a Chevy 2 1/2 with a 4-53 Detroit with a turbo and fuel mileage was real good
it had 900-20 tires 5 speed transmission 2 speed rear end . under powered when pulling a loaded 35 foot tandem axle trailer .

greywuuf · 12-07-2018, 06:39 PM

Real good compared to a semi, or Compared to a pickup?...I am hearing horror stories of. 3-5 mpg and am personally assuming 6-8 as a norm, was hoping to be able to approach ten with a little taller tire and car full attention to weight and loading.

C10 - C90 Bill · 12-07-2018, 10:46 PM

I never did figure the mileage on my '67 7500 with the 6V-53, but it didn't seem that bad. My guess would be an all around 8 or 9, maybe even a little better, especially empty or with a light load.

My 2-53 in my John Deere uses hardly any fuel at all. It's hard to believe how little it uses.

Good to see you back on the forum.

I was wondering how you are doing.

greywuuf · 12-08-2018, 01:20 AM

Thanks for the welcome, I tend to hop from project to project. This summer was rebuilding the old Lincoln ranger welder/genset. It managed to get my son interested in welding and working on stuff. He turns 16 Feb after this one and we cleared it with Mom, him and I are road tripping to the states in celebration of his DL. I have roughly 14 months to figure it out.

Tenative plans are for a little taller tires and a bed mounted pop up overland style camper on the flatbed of my single axle 7500. ...man I wish I could find a road ranger with OD to go in her before then. Just trying to freshen her up a little and get the road speed up a touch and then just put some miles on her.

Airdirect · 12-08-2018, 01:30 AM

I have a John Deere 435 Diesel with a 2-53 NA. We use it to pull a 8ft finish mower. It has a small tank, around 12 gallons and it will last forever. It is hard to imagine how little fuel the tractor uses. I also have a Chevrolet C70 with a 4-53T, 5 speed and two speed axle. Empty I get around 13 MPG. Back in the 70's I drove a IHC Fleetstar 1900 with a 6-53 NA. It had a 8 speed fuller transmission. I do not remember anything about fuel mileage as I was not paying the bills. I do remember it pulled very good and sounded great! The engine was a transplant into the truck after the original DV550 IH Diesel died. The DV550 was 210 hp and the 6-53 had lots more power. The thing I remember about the 6-53 was it did not leak oil like the 6-71 in our GMC 9500. Basically a very good motor if you like Detroits.

greywuuf · 12-08-2018, 01:42 AM

I do like the Detroit's, but I am just playing with them, not trying to make a living.

Airdirect · 12-08-2018, 01:50 AM

Be careful to not gear it too high. You want the Detroit within 100 to 200 of max RPM at the desired highway speed. Below that and the mileage will tank as the engine will be bogged down with full fuel rack and no air. My C70 is geared to maximum RPM at 71 MPH. My goal was to be able to cruise at 65 MPH. In reality it likes 68 MPH. Slower than 68 the power really starts to fall off. It has a really narrow power band. If my memory serves me correctly the 6-53 might have a slightly wider power band than my 4-53T.

greywuuf · 12-08-2018, 03:53 AM

I don't think the powerband was necessarily any wider ( maybe the turbo made a difference) but the 6v ( just by virtue of more displacement) might be slightly more tolerant of the lower side of the power band... however I am pretty much topped out at about 45-50 MPH this truck was converted to 4x4 (FABCO) and put to work on the Alaska pipeline construction job ( no pavement and not concerned about going fast) the T case and front axle were later removed but it still has the LOW geared rear end not exactly sure how low but as I said she is would up ( 2850) at just around 50 mph. Also it is encouraging that you can make 70 mph on 4 cylinder C70 !

greywuuf · 12-08-2018, 04:05 AM

oh yeah I still have this little issue …
http://youtu.be/lBYbFUcGqtE

Airdirect · 12-08-2018, 11:56 AM

Wow! I did not know they offered Lane Assist back then. Pretty cool option.

Seriously I expect if you take apart the valve portion you will find the problem. The valve is the part where all the hoses attach to the steering box.

greywuuf · 12-08-2018, 11:33 PM

Yeah I tore the valve apart and there was a locating pin that was not in place ...jamming the spool.. I put it back together and ordered a seal kit ...just waiting to pull the entire box off and figure out how to actually get the sector out so I can remove the valve completely to re seal it.

12-07-2018, 03:39 PM	#1
greywuuf Registered User Join Date: Jul 2007 Location: Alaska Posts: 517	1975 H70 w 6V53. Mpg? So I have a dream a truck and some time. I know Detroit's are thirsty....but given that I have a "7500" series with a 6V53n that I plan to road trip with. What is my best option for maybe the best mileage ? Currently it is a single speed with a 5 speed and 20" splits....hoping to go 22.5 one piece . Also open to transmission upgrade. I figure a little taller tire and keeping it light are about all I can do to see better fuel consumption. Anyway a small camper shell, lightweight pop-up tent style less than 1000 pounds all loaded up, and not sticking up in the wind. What kind of fuel burn am I looking at ?

12-07-2018, 04:18 PM	#2
Bimus Registered User Join Date: Dec 2018 Location: Farmington NM Posts: 112	Re: 1975 H70 w 6V53. Mpg? I drove a Chevy 2 1/2 with a 4-53 Detroit with a turbo and fuel mileage was real good it had 900-20 tires 5 speed transmission 2 speed rear end . under powered when pulling a loaded 35 foot tandem axle trailer .

12-07-2018, 06:39 PM	#3
greywuuf Registered User Join Date: Jul 2007 Location: Alaska Posts: 517	Re: 1975 H70 w 6V53. Mpg? Real good compared to a semi, or Compared to a pickup?...I am hearing horror stories of. 3-5 mpg and am personally assuming 6-8 as a norm, was hoping to be able to approach ten with a little taller tire and car full attention to weight and loading.

12-07-2018, 10:46 PM	#4
C10 - C90 Bill Registered User Join Date: Nov 2001 Location: Moneta, VA USA Posts: 3,088	Re: 1975 H70 w 6V53. Mpg? I never did figure the mileage on my '67 7500 with the 6V-53, but it didn't seem that bad. My guess would be an all around 8 or 9, maybe even a little better, especially empty or with a light load. My 2-53 in my John Deere uses hardly any fuel at all. It's hard to believe how little it uses. Good to see you back on the forum. I was wondering how you are doing. __________________ '60-'72 Chev/GMC Fan GMC 9500 Fan Detroit Diesel Fan

12-08-2018, 01:20 AM	#5
greywuuf Registered User Join Date: Jul 2007 Location: Alaska Posts: 517	Re: 1975 H70 w 6V53. Mpg? Thanks for the welcome, I tend to hop from project to project. This summer was rebuilding the old Lincoln ranger welder/genset. It managed to get my son interested in welding and working on stuff. He turns 16 Feb after this one and we cleared it with Mom, him and I are road tripping to the states in celebration of his DL. I have roughly 14 months to figure it out. Tenative plans are for a little taller tires and a bed mounted pop up overland style camper on the flatbed of my single axle 7500. ...man I wish I could find a road ranger with OD to go in her before then. Just trying to freshen her up a little and get the road speed up a touch and then just put some miles on her.

12-08-2018, 01:30 AM	#6
Airdirect Registered User Join Date: Oct 2016 Location: Powderly Texas Posts: 306	Re: 1975 H70 w 6V53. Mpg? I have a John Deere 435 Diesel with a 2-53 NA. We use it to pull a 8ft finish mower. It has a small tank, around 12 gallons and it will last forever. It is hard to imagine how little fuel the tractor uses. I also have a Chevrolet C70 with a 4-53T, 5 speed and two speed axle. Empty I get around 13 MPG. Back in the 70's I drove a IHC Fleetstar 1900 with a 6-53 NA. It had a 8 speed fuller transmission. I do not remember anything about fuel mileage as I was not paying the bills. I do remember it pulled very good and sounded great! The engine was a transplant into the truck after the original DV550 IH Diesel died. The DV550 was 210 hp and the 6-53 had lots more power. The thing I remember about the 6-53 was it did not leak oil like the 6-71 in our GMC 9500. Basically a very good motor if you like Detroits.

12-08-2018, 01:42 AM	#7
greywuuf Registered User Join Date: Jul 2007 Location: Alaska Posts: 517	Re: 1975 H70 w 6V53. Mpg? I do like the Detroit's, but I am just playing with them, not trying to make a living.

12-08-2018, 01:50 AM	#8
Airdirect Registered User Join Date: Oct 2016 Location: Powderly Texas Posts: 306	Re: 1975 H70 w 6V53. Mpg? Be careful to not gear it too high. You want the Detroit within 100 to 200 of max RPM at the desired highway speed. Below that and the mileage will tank as the engine will be bogged down with full fuel rack and no air. My C70 is geared to maximum RPM at 71 MPH. My goal was to be able to cruise at 65 MPH. In reality it likes 68 MPH. Slower than 68 the power really starts to fall off. It has a really narrow power band. If my memory serves me correctly the 6-53 might have a slightly wider power band than my 4-53T.

12-08-2018, 03:53 AM	#9
greywuuf Registered User Join Date: Jul 2007 Location: Alaska Posts: 517	Re: 1975 H70 w 6V53. Mpg? I don't think the powerband was necessarily any wider ( maybe the turbo made a difference) but the 6v ( just by virtue of more displacement) might be slightly more tolerant of the lower side of the power band... however I am pretty much topped out at about 45-50 MPH this truck was converted to 4x4 (FABCO) and put to work on the Alaska pipeline construction job ( no pavement and not concerned about going fast) the T case and front axle were later removed but it still has the LOW geared rear end not exactly sure how low but as I said she is would up ( 2850) at just around 50 mph. Also it is encouraging that you can make 70 mph on 4 cylinder C70 !

12-08-2018, 04:05 AM	#10
greywuuf Registered User Join Date: Jul 2007 Location: Alaska Posts: 517	Re: 1975 H70 w 6V53. Mpg? oh yeah I still have this little issue … http://youtu.be/lBYbFUcGqtE Last edited by greywuuf; 12-08-2018 at 04:10 AM.

12-08-2018, 11:56 AM	#11
Airdirect Registered User Join Date: Oct 2016 Location: Powderly Texas Posts: 306	Re: 1975 H70 w 6V53. Mpg? Wow! I did not know they offered Lane Assist back then. Pretty cool option. Seriously I expect if you take apart the valve portion you will find the problem. The valve is the part where all the hoses attach to the steering box.

12-08-2018, 11:33 PM	#12
greywuuf Registered User Join Date: Jul 2007 Location: Alaska Posts: 517	Re: 1975 H70 w 6V53. Mpg? Yeah I tore the valve apart and there was a locating pin that was not in place ...jamming the spool.. I put it back together and ordered a seal kit ...just waiting to pull the entire box off and figure out how to actually get the sector out so I can remove the valve completely to re seal it.



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