67-72 3/4 ton with good gas mileage - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mitchfab · 06-16-2005, 01:51 PM

Whats it going to take to get 20 miles to a gallon with a 402?

Maximum Overdrive · 06-16-2005, 01:53 PM

Stick the 402 in the box and put in a straight six.

mikeoj · 06-16-2005, 01:53 PM

A miracle!!

chevyfarmer · 06-16-2005, 01:55 PM

A flat bed trailer, a tow bar, or a steep long hill, as long as the engine is not running.....

mitchfab · 06-16-2005, 01:57 PM

No Lets get serious!

67ChevyRedneck · 06-16-2005, 02:16 PM

Quote:

Originally Posted by mitchfab

No Lets get serious!

Everyone is dead serious bro. My 2000 Z-71 with a 327 and fuel injection will get 18.3 highway if I'm easy on her. My 67 with 350/700R4/3.73 will get 16 highway. Even the brand spakin new chevy truck regular cab 2wd with the 4.3L fuel injected V-6 and a 5speed tranny is listed at 21mpg. 20 mpg out of a big block???? Fuel injection, fiberglass body, 6 speed, aluminum rims, skinny driver, empty bed.... and you shut it off and roll it down a hill for 5 of the 20 miles

I believe txfirefighter has said before that he has a 67-72(dont remember the year) with a straight six and 5speed (again, cant remember for sure) but I think he said he could get 21mpg with it??? I apologize if this is wrong, but my memory sucks.

67_C-30 · 06-16-2005, 11:40 PM

Quote:

Originally Posted by 67ChevyRedneck

Everyone is dead serious bro. My 2000 Z-71 with a 327 and fuel injection will get 18.3 highway if I'm easy on her. My 67 with 350/700R4/3.73 will get 16 highway. Even the brand spakin new chevy truck regular cab 2wd with the 4.3L fuel injected V-6 and a 5speed tranny is listed at 21mpg. 20 mpg out of a big block???? Fuel injection, fiberglass body, 6 speed, aluminum rims, skinny driver, empty bed.... and you shut it off and roll it down a hill for 5 of the 20 miles

I believe txfirefighter has said before that he has a 67-72(dont remember the year) with a straight six and 5speed (again, cant remember for sure) but I think he said he could get 21mpg with it??? I apologize if this is wrong, but my memory sucks.

Not that it matters or makes a difference, but your 2000 Z71 engine is a 325 cu in. (3.780" x 3.62)

But I agree that 20MPG with a BBC is very optimistic is a truck, even with EFI and OD. They get about 1/2 that in stock form even in newer model trucks.

67ChevyRedneck · 06-17-2005, 08:27 AM

Quote:

Originally Posted by 67_C-30

Not that it matters or makes a difference, but your 2000 Z71 engine is a 325 cu in. (3.780" x 3.62)

But I agree that 20MPG with a BBC is very optimistic is a truck, even with EFI and OD. They get about 1/2 that in stock form even in newer model trucks.

I've been confused on that for quite some time. Some people say it's a 327 and some say its a 325. I recently went to chevrolets site and they have a 5300V8 listed as 327cu/5360cc and a 5300 H.O. V8 listed as 325cu/5360cc. I'm pretty sure my truck isn;t an "H.O." version so it's a 327??? I know these are listed for new trucks, but they started using the engine in 99...so....

Here's the site GM truck engine specs then click on the "engine" tab.

dallas71 · 06-16-2005, 01:58 PM

I think we are all are being serious.....h@ll i can't evern get that on a newer truck with all of the bells and whistles!!

mitchfab · 06-16-2005, 01:59 PM

Can it be done with a 91 fi big block setup with a 400 tranny?

lilred67 · 06-16-2005, 01:59 PM

my 6 cylinder wouldn't get that with overdrive and 3.08's

mitchfab · 06-16-2005, 02:01 PM

These gas prices are bad! Lets all get together and make it better with a big block!

chevyfarmer · 06-16-2005, 02:05 PM

I would highly doubt that the th400 would be what you are looking for but a 700r4 might be. This has kinda got me thinking, what is the best mileage anyone has got with a BBC? I just dont think of gas mileage as being a goal with a big block.

thecatseye66 · 06-16-2005, 02:07 PM

My C-20 396 with a Holley two barrel gets about 16 on the highway if I baby it. Around town or towing I'm just under 14--again, driving like a bluehair. I doubt I could do much to make it lower.

I just sit in the truck a lot now and pretend I'm driving real fast...

69sixpackbee · 06-16-2005, 06:28 PM

Quote:

Originally Posted by mitchfab

These gas prices are bad! Lets all get together and make it better with a big block!

Bad prices? Hell, son, you're in TX. Try coming to California!

OlyHeeebz · 06-16-2005, 06:50 PM

What do you guys think swapping a 6.2L diesel in would do for you? I saw someone on this board has done it. With all that torque, you could put some tall gears in the back (3.07's or taller), with an overdrive tranny, you might come out doing pretty well on the mpg's.

If I had better knowledge of how to do the swap and a donor engine, i'd consider doing it.

mitchfab · 06-16-2005, 02:03 PM

Anyone got a tbi smallblock that will get 20?

Cat Fuzz · 06-16-2005, 06:12 PM

Quote:

Originally Posted by mitchfab

Anyone got a tbi smallblock that will get 20?

I had a 77 Monte Carlo with a 327, Carter 4 barrel, aluminum intake, dual exhaust and all emission equipment removed. It not only passed emissions, it passed beating the standard for a 2 year old car and it got 21 MPG. It must have had something to do with the 2.56 gears in the rear

That same engine is now in my truck and it gets about 15mpg now.

jtminton · 06-16-2005, 02:04 PM

I can do it, if you double the size of a gallon.

mitchfab · 06-16-2005, 02:06 PM

Ok I got a buddy with a 97 chevy that gets 24 with a 5.7

Project1970 · 06-16-2005, 05:20 PM

Quote:

Originally Posted by mitchfab

Ok I got a buddy with a 97 chevy that gets 24 with a 5.7

Your buddy is full of it, or rarely exceeds 55mph. One or the other.

mitchfab · 06-16-2005, 05:45 PM

Quote:

Originally Posted by Project1970

Your buddy is full of it, or rarely exceeds 55mph. One or the other.

That could be true. But it we all got Big Boots here in EastTexas

mitchfab · 06-16-2005, 02:09 PM

I would love to get a bb around 20 .I bet it would take a 4l60 or 80 to do it.

chevyfarmer · 06-16-2005, 02:11 PM

Quote:

Originally Posted by mitchfab

I would love to get a bb around 20 .I bet it would take a 4l60 or 80 to do it.

I would like 20 and I imagine a lot of people would like to get 20 with a SBC let alone a BBC, what do you mean by an 80?

mitchfab · 06-16-2005, 02:11 PM

Thats good for a two barrel!

06-16-2005, 01:51 PM	#1
mitchfab Junk Chevy C20 Big Block Join Date: Jun 2005 Location: East Texas Posts: 68	67-72 3/4 ton with good gas mileage Whats it going to take to get 20 miles to a gallon with a 402?

06-16-2005, 01:53 PM	#2
Maximum Overdrive December 21, 2012 Join Date: Apr 2000 Location: Black Eagle, Montana Posts: 1,633	Stick the 402 in the box and put in a straight six. __________________ *"!Ama Sua, Ama Kjella, Ama Lllulla!"*

06-16-2005, 01:53 PM	#3
mikeoj Senior Member Join Date: Nov 2000 Location: WI,USA Posts: 495	A miracle!! __________________ 69 Lwb C-10 402/700R4 70 Lwb C-10 250/3pd Wisc.

06-16-2005, 01:55 PM	#4
chevyfarmer Registered User Join Date: Feb 2005 Location: Owosso, Mi Posts: 242	A flat bed trailer, a tow bar, or a steep long hill, as long as the engine is not running..... __________________ 67 short wide 355ci 3 on tree 69 short wide 250ci 3 on tree 68 long wide 283 3 on tree 72 2wd Blazer project 454 5 speed Last edited by chevyfarmer; 06-16-2005 at 01:56 PM.

06-16-2005, 01:58 PM	#9
dallas71 Registered User Join Date: Mar 2004 Location: Corinth,TX Posts: 444	I think we are all are being serious.....h@ll i can't evern get that on a newer truck with all of the bells and whistles!! __________________ My 1966 LWB Truck My 1966 SWB Truck

06-16-2005, 01:57 PM	#5
mitchfab Junk Chevy C20 Big Block Join Date: Jun 2005 Location: East Texas Posts: 68	No Lets get serious!

06-16-2005, 01:59 PM	#10
mitchfab Junk Chevy C20 Big Block Join Date: Jun 2005 Location: East Texas Posts: 68	Can it be done with a 91 fi big block setup with a 400 tranny?

06-16-2005, 01:59 PM	#11
lilred67 Senior Member Join Date: Mar 2005 Location: weatherford,texas Posts: 1,003	my 6 cylinder wouldn't get that with overdrive and 3.08's

06-16-2005, 02:01 PM	#12
mitchfab Junk Chevy C20 Big Block Join Date: Jun 2005 Location: East Texas Posts: 68	These gas prices are bad! Lets all get together and make it better with a big block!

06-16-2005, 02:05 PM	#13
chevyfarmer Registered User Join Date: Feb 2005 Location: Owosso, Mi Posts: 242	I would highly doubt that the th400 would be what you are looking for but a 700r4 might be. This has kinda got me thinking, what is the best mileage anyone has got with a BBC? I just dont think of gas mileage as being a goal with a big block. __________________ 67 short wide 355ci 3 on tree 69 short wide 250ci 3 on tree 68 long wide 283 3 on tree 72 2wd Blazer project 454 5 speed

06-16-2005, 02:07 PM	#14
thecatseye66 '68 C-20 396 CST CC Join Date: Mar 2005 Location: Spokane, WA Posts: 454	My C-20 396 with a Holley two barrel gets about 16 on the highway if I baby it. Around town or towing I'm just under 14--again, driving like a bluehair. I doubt I could do much to make it lower. I just sit in the truck a lot now and pretend I'm driving real fast... __________________ 68 C-20 396/TH400 CST Custom Camper NOW W/DISC BRAKES 01 Jetta Turbo Daily Driver 84 Yamaha Virago 700 - Alaska to Florida Via Maine & Mexico

06-16-2005, 06:50 PM	#16
OlyHeeebz Registered User Join Date: Jan 2005 Location: Seattle, WA Posts: 41	How about a diesel engine swap? What do you guys think swapping a 6.2L diesel in would do for you? I saw someone on this board has done it. With all that torque, you could put some tall gears in the back (3.07's or taller), with an overdrive tranny, you might come out doing pretty well on the mpg's. If I had better knowledge of how to do the swap and a donor engine, i'd consider doing it. __________________ 1969 K5 Blazer CST Always waiting for the Puget Sound sun.....

06-16-2005, 02:03 PM	#17
mitchfab Junk Chevy C20 Big Block Join Date: Jun 2005 Location: East Texas Posts: 68	Anyone got a tbi smallblock that will get 20?

06-16-2005, 02:04 PM	#19
jtminton II Timothy 4:2 Join Date: Mar 2005 Location: Fort Worth Posts: 361	I can do it, if you double the size of a gallon. __________________ 72 C-20 2WD LWB Custom Camper Deluxe 350 4 Speed "Project Lazarus" MY TRUE PRIDE AND JOY "Dangit, Bobby, people will see that oil stain and think I'm a drunk."

06-16-2005, 02:06 PM	#20
mitchfab Junk Chevy C20 Big Block Join Date: Jun 2005 Location: East Texas Posts: 68	Ok I got a buddy with a 97 chevy that gets 24 with a 5.7



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06-16-2005, 02:09 PM	#23
mitchfab Junk Chevy C20 Big Block Join Date: Jun 2005 Location: East Texas Posts: 68	I would love to get a bb around 20 .I bet it would take a 4l60 or 80 to do it.

06-16-2005, 02:11 PM	#25
mitchfab Junk Chevy C20 Big Block Join Date: Jun 2005 Location: East Texas Posts: 68	Thats good for a two barrel!

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