Saddle tank delete with carburation

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Bloodhound1981

Full Access Member
Joined
Nov 15, 2016
Posts
201
Reaction score
453
Location
MA
First Name
Rusty
Truck Year
1981
Truck Model
C-10
Engine Size
5.7
I did this with a 31 gallon plastic Blazer tank. The 40 gallon tank is the same footprint, its just deeper so it hangs down lower. This is on a EFI application (1981 C-10 frame). Had to remove the crossmemeber for the spare tire carrier, and add a new crossmember to support the tank. I also mounted the tank backwards from the way it is supposed to in a Blazer so that the filler is pointed towards the driver side. All in all pretty simple.

You must be registered for see images attach
 

scrap--metal

Full Access Member
Joined
Sep 15, 2021
Posts
691
Reaction score
1,314
Location
MN
First Name
Calvin
Truck Year
'85, '81
Truck Model
K10, K20
Engine Size
305, 350
Body swap to an M37.

Is there some kind of reason to keep them?
If it ain't broke, don't fix it. Leave the saddle tanks under the M37.
 

Camar068

Supporting Member
Supporting Member
Joined
Feb 5, 2014
Posts
4,291
Reaction score
3,335
Location
Kentucky
First Name
David
Truck Year
1986
Truck Model
K10/LM7 5.3/4L60e/np208/3.73/32"
Engine Size
10 yrs Air Force

RecklessWOT

Full Access Member
Joined
Feb 20, 2015
Posts
2,556
Reaction score
4,764
Location
New Hampshire
First Name
Kevin
Truck Year
1987
Truck Model
V10 Suburban Silverado
Engine Size
350 TBI
Body swap to an M37.

Is there some kind of reason to keep them?
They already exist and hold fuel just fine. Is there some reason to get rid of them? Swapping is just more work and expense for no real gain.
 

Travlr

Full Access Member
Joined
Sep 18, 2023
Posts
230
Reaction score
746
Location
Central Utah
First Name
C
Truck Year
1978
Truck Model
K20 Camper Special
Engine Size
350
They already exist and hold fuel just fine. Is there some reason to get rid of them? Swapping is just more work and expense for no real gain.
You know I'm doing a body swap... right? Putting an M37 body on the Chevy frame?
 

RecklessWOT

Full Access Member
Joined
Feb 20, 2015
Posts
2,556
Reaction score
4,764
Location
New Hampshire
First Name
Kevin
Truck Year
1987
Truck Model
V10 Suburban Silverado
Engine Size
350 TBI
You know I'm doing a body swap... right? Putting an M37 body on the Chevy frame?
I'm not intimately familiar with the shape of the underside of an M37 cab. What prevents the use of saddle tanks, the body still mounts above the frame, right? Are there things sticking down under it or something? If there's a reason then there's a reason, I'm not saying I know more about it than you do, but you could explain it for those of us that don't know. When I hear about someone doing a body swap my first thought isn't immediately "quick, get rid of the fuel tank!" so even though I read you were swapping the body, I still don't completely understand the reason for getting rid of them.
 

Craig Nedrow

NADAR UNDER THE RADAR
Supporting Member
Joined
Sep 1, 2018
Posts
1,035
Reaction score
2,168
Location
Washington State
First Name
Craig
Truck Year
1973 (have two), 1985
Truck Model
K10, K20, C20
Engine Size
350, 454, 6.2 Detroit
I remember our old power wagon gas tank was under the bed (flat bed) outside of the frame just a square tank. Seems like the square body tanks would work,
 

Bextreme04

Full Access Member
Joined
May 13, 2019
Posts
4,439
Reaction score
5,572
Location
Oregon
First Name
Eric
Truck Year
1980
Truck Model
K25
Engine Size
350-4bbl
I did this with a 31 gallon plastic Blazer tank. The 40 gallon tank is the same footprint, its just deeper so it hangs down lower. This is on a EFI application (1981 C-10 frame). Had to remove the crossmemeber for the spare tire carrier, and add a new crossmember to support the tank. I also mounted the tank backwards from the way it is supposed to in a Blazer so that the filler is pointed towards the driver side. All in all pretty simple.

You must be registered for see images attach
The 40 gallon is NOT the same footprint.
The 31 Gallon is 28.75"x28.125"x12.75"
The 40 Gallon is 28.75"x35"x13.13"

Its only ~ 0.5" taller, but it extends and extra 7" longer and basically fits right up against(or maybe even a little bit over the top of) the rear diff. It can work fine if you have a decent lift on the truck and aren't planning on doing any crazy offroading, but it definitely is a lot closer than the 31 Gallon. I have the 31 Gallon retrofitted into my 1980 K25 and am running it to my carbureted engine currently. It will eventually get an EP381 pump dropped into it when I swap in the 454/4L80. I needed to move the forward rear spring mounts 4" forward in order to swap in 63" rear springs and I am also flattening the floors to better fit the seats I have for it, so it was killing two birds with one stone to put in the EFI blazer tank and remove the saddle tanks. It has worked well for over a year now.

I got the original crossmembers, mounting straps, filler neck, and filler door stuff with the tank when I bought it locally from a guy. He had cut it all out of a blazer at the wrecking yard with the intention of using it for a swap as well.
 

Bloodhound1981

Full Access Member
Joined
Nov 15, 2016
Posts
201
Reaction score
453
Location
MA
First Name
Rusty
Truck Year
1981
Truck Model
C-10
Engine Size
5.7
The 40 gallon is NOT the same footprint.
The 31 Gallon is 28.75"x28.125"x12.75"
The 40 Gallon is 28.75"x35"x13.13"

Its only ~ 0.5" taller, but it extends and extra 7" longer and basically fits right up against(or maybe even a little bit over the top of) the rear diff. It can work fine if you have a decent lift on the truck and aren't planning on doing any crazy offroading, but it definitely is a lot closer than the 31 Gallon. I have the 31 Gallon retrofitted into my 1980 K25 and am running it to my carbureted engine currently. It will eventually get an EP381 pump dropped into it when I swap in the 454/4L80. I needed to move the forward rear spring mounts 4" forward in order to swap in 63" rear springs and I am also flattening the floors to better fit the seats I have for it, so it was killing two birds with one stone to put in the EFI blazer tank and remove the saddle tanks. It has worked well for over a year now.

I got the original crossmembers, mounting straps, filler neck, and filler door stuff with the tank when I bought it locally from a guy. He had cut it all out of a blazer at the wrecking yard with the intention of using it for a swap as well.
Good to knpw, I was given bad intel.
 

Craig Nedrow

NADAR UNDER THE RADAR
Supporting Member
Joined
Sep 1, 2018
Posts
1,035
Reaction score
2,168
Location
Washington State
First Name
Craig
Truck Year
1973 (have two), 1985
Truck Model
K10, K20, C20
Engine Size
350, 454, 6.2 Detroit
The 40 gallon is NOT the same footprint.
The 31 Gallon is 28.75"x28.125"x12.75"
The 40 Gallon is 28.75"x35"x13.13"

Its only ~ 0.5" taller, but it extends and extra 7" longer and basically fits right up against(or maybe even a little bit over the top of) the rear diff. It can work fine if you have a decent lift on the truck and aren't planning on doing any crazy offroading, but it definitely is a lot closer than the 31 Gallon. I have the 31 Gallon retrofitted into my 1980 K25 and am running it to my carbureted engine currently. It will eventually get an EP381 pump dropped into it when I swap in the 454/4L80. I needed to move the forward rear spring mounts 4" forward in order to swap in 63" rear springs and I am also flattening the floors to better fit the seats I have for it, so it was killing two birds with one stone to put in the EFI blazer tank and remove the saddle tanks. It has worked well for over a year now.

I got the original crossmembers, mounting straps, filler neck, and filler door stuff with the tank when I bought it locally from a guy. He had cut it all out of a blazer at the wrecking yard with the intention of using it for a swap as well.
Eric, you gonna swap the 454 this winter? Your gonna love that. What is the motor out of?
 

Bextreme04

Full Access Member
Joined
May 13, 2019
Posts
4,439
Reaction score
5,572
Location
Oregon
First Name
Eric
Truck Year
1980
Truck Model
K25
Engine Size
350-4bbl
Eric, you gonna swap the 454 this winter? Your gonna love that. What is the motor out of?
Hope so, I’ve been working on it slowly but surely and now it’s been sitting completed in the garage for about a year now waiting to go in, but something always ends up taking priority. Really hoping to do it this month. Engine/trans and wiring harness came from a 97 K2500 Suburban.
 

Craig Nedrow

NADAR UNDER THE RADAR
Supporting Member
Joined
Sep 1, 2018
Posts
1,035
Reaction score
2,168
Location
Washington State
First Name
Craig
Truck Year
1973 (have two), 1985
Truck Model
K10, K20, C20
Engine Size
350, 454, 6.2 Detroit
Pictures? What I just finished for my good wife.
 

Attachments

  • IMG_0454.jpeg
    IMG_0454.jpeg
    206.7 KB · Views: 49

Forum statistics

Threads
44,074
Posts
948,838
Members
36,144
Latest member
wolfdog63
Top