MPG poll - Page 7 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cab4word67 · 09-15-2021, 11:50 AM

I just did 1700 miles at 70 MPG with 3 mt passes both ways, got 11 as an average but saw 13 on first tank
ZZ4 sbc, 650 eldie, 700R w/lock up, 4:11s and 28.5" tires. runs at 2550 rpms

**special-K** · 09-15-2021, 08:25 PM

Quote:

Originally Posted by Dieselwrencher

My 72 gets 16.5 city if I drive it like normal. It's gotten 20 on the hwy.

I'm supposed to say "BS", but you have a Cummins and O/D. So it's, "BS. It's not better than that? When's the last time you changed your plugs?"

**HO455** · 09-15-2021, 09:55 PM

Quote:

Originally Posted by special-K

I'm supposed to say "BS", but you have a Cummins and O/D. So it's, "BS. It's not better than that? When's the last time you changed your plugs?"

Lancialonnie · 09-15-2021, 11:40 PM

I was so disappointed that after installing a Blueprint 383 and 700r4 that I could barely manage 8 mpg! Even using just 3rd and not OD it didn't improve much as I think the engine just isn't operating efficiently at such low rpm. I still had the 3.07 gears so, as soon as my buddy has room at his shop the new yukon dura grip carrier and 3.73 gears are going in. I hope it helps! If nothing else it'll be more smiles to the gallon!

lil hoodlum · 09-16-2021, 12:37 AM

I had a 327 rebuilt at a local machine shop. I had it installed by another shop. After I got it back and ran it through the paces of breaking in a "newly" machined motor, I was shocked that I was only getting 8MPG. It did take a little while to fully break in that motor as it is my daily driver but it gets a solid 13 or so MPG every week. Not the greatest for sure but it does ok for me now.

327, 3 speed manual, 3:73 to 1 rear end gears.

Warrens69GMC · 09-16-2021, 02:10 AM

Quote:

Originally Posted by Lancialonnie

I was so disappointed that after installing a Blueprint 383 and 700r4 that I could barely manage 8 mpg! Even using just 3rd and not OD it didn't improve much as I think the engine just isn't operating efficiently at such low rpm. I still had the 3.07 gears so, as soon as my buddy has room at his shop the new yukon dura grip carrier and 3.73 gears are going in. I hope it helps! If nothing else it'll be more smiles to the gallon!

run your numbers with 3.55

**Dieselwrencher** · 09-16-2021, 05:10 AM

Quote:

Originally Posted by special-K

I'm supposed to say "BS", but you have a Cummins and O/D. So it's, "BS. It's not better than that? When's the last time you changed your plugs?"

It has enough fuel for 2 engines is part of that issue.

But it does have 2 spinny mufflers.

geezer#99 · 09-16-2021, 10:51 AM

Quote:

Originally Posted by Lancialonnie

I was so disappointed that after installing a Blueprint 383 and 700r4 that I could barely manage 8 mpg! Even using just 3rd and not OD it didn't improve much as I think the engine just isn't operating efficiently at such low rpm. I still had the 3.07 gears so, as soon as my buddy has room at his shop the new yukon dura grip carrier and 3.73 gears are going in. I hope it helps! If nothing else it'll be more smiles to the gallon!

A change to 3.73’s won’t make any difference.
In 3rd with your present 3.07’s your 383 doesn’t like 2400 rpm at 65mph.
In third with 3.73’s it’ll be 2900 rpm. Much better.
In o/d you’ll be worse off at 2100 rpm.

At least you’ll have smiles per gallon!

View Poll Results: What's your MPG?
Less than 7 MPG...I should own stock in the oil fields.	33	6.48%
7 to 9 MPG ... can I get some gas money please?	86	16.90%
10 to 12 MPG ... And I thought I had it bad...look at those suckers getting less!	198	38.90%
13 to 14 MPG ... Yeah... I'm doing OK	103	20.24%
15 to 17 MPG ... Heh...I'm doin better than the new trucks!	60	11.79%
18 to 20 MPG ... Why does everyone say B.S. when i tell them this????	20	3.93%
20+ I am a compulsive lier and I am stoned. (j/k if anyone here actually DOES do this good.... or if you are a lier and a stoner and feel insulted)	20	3.93%
MPG... Whats that? I get KPL and it is so wierd that you americans never seem to be able to figure it out.	12	2.36%
Multiple Choice Poll. Voters: 509. You may not vote on this poll

09-15-2021, 11:50 AM	#151
cab4word67 Registered User Join Date: Sep 2020 Location: portland oregon Posts: 183	Re: MPG poll I just did 1700 miles at 70 MPG with 3 mt passes both ways, got 11 as an average but saw 13 on first tank ZZ4 sbc, 650 eldie, 700R w/lock up, 4:11s and 28.5" tires. runs at 2550 rpms

09-15-2021, 11:40 PM	#154
Lancialonnie Registered User Join Date: Jul 2015 Location: Vacaville CA Posts: 153	Re: MPG poll I was so disappointed that after installing a Blueprint 383 and 700r4 that I could barely manage 8 mpg! Even using just 3rd and not OD it didn't improve much as I think the engine just isn't operating efficiently at such low rpm. I still had the 3.07 gears so, as soon as my buddy has room at his shop the new yukon dura grip carrier and 3.73 gears are going in. I hope it helps! If nothing else it'll be more smiles to the gallon!

09-16-2021, 12:37 AM	#155
lil hoodlum Registered User Join Date: Oct 2009 Location: Denton, Texas Posts: 1,695	Re: MPG poll I had a 327 rebuilt at a local machine shop. I had it installed by another shop. After I got it back and ran it through the paces of breaking in a "newly" machined motor, I was shocked that I was only getting 8MPG. It did take a little while to fully break in that motor as it is my daily driver but it gets a solid 13 or so MPG every week. Not the greatest for sure but it does ok for me now. 327, 3 speed manual, 3:73 to 1 rear end gears. __________________ 1968 C10 327, 3 speed manual, LWB stock height daily driver. 1968 C20 327, 4 speed manual, LWB stock height custom camper with heavy duty leaf springs rear, 50th anniversary edition. Hoping to press into daily drive status soon.



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