Another 4x BB swap thread - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jwhitfield · 07-22-2003, 05:35 PM

I figured that I set this up as a new thread, maybe it will get more response.

There seems to be several of us planning a BB swap. As I've said in the past, my original thought was that the job would be relatively simple. I too thought the 4x4s came with BBs. I've since learned otherwise. There seems to be two trains of thought out there. 1. You don't need to move anything forward, but everything is a tight fit. Some minor grinding and love tapping. 2. Move everything forward 2-2.5 inches.

I have yet to start my project, so I haven't got a good look at the components and crossmembers. My questions are with respect to the relocating of the driveline.
When you say move everything forward I'm assuming that means engine, tranny and transfercase. How is this done exactly? Is there enough space on the various crossmembers and supports to drill another set of holes or do you have to move those as well?
How about moving things 1", is that a good compromise?

Sorry for the length here, but if I take on this project, I'd like to get it done in my life time. The more I know up front, the better prepared I'll be to make the decision....

NAPCO ken · 07-22-2003, 05:45 PM

What year are you working on? I have a Chev 454 in my '60 GMC Suburban 4x4.

jwhitfield · 07-22-2003, 08:14 PM

I have a 72 lwb 4x4. 350/350 The engine is completely tired and I was thinking about swapping in a 396 that I have. I though it was going to be easy, but seems as though it's going to be another high dollar/time project....

NAPCO ken · 07-23-2003, 10:50 AM

I believe that in '72 you could have gotten the 402 as an optional motor in 4x4s. Shouldn't be that much work to install a big block.

jwhitfield · 07-23-2003, 11:05 AM

Myself, I don't know, but many of the board members have said that BBs didn't come in the 4x4s. I do know that I have not been able to find any listing for motor mount stands. Guess I just have to dive in and see for myself....

**breeh** · 07-23-2003, 12:48 PM

There was no big block option in 4x4's from 67-72. I chose to move "everything" forward 2". It is really not that big of deal to do. The most difficult part is figuring out where to redrill the holes for the torque bracket which hangs off of the side of the transfer case. I am not sure what limiting yourself to a 1" move is going to accomplish. As long as you are redrilling, you might as well go the 2". Basically, unbolt engine crossmember. slide it forward. On the driver's side there is an existing set of holes that I lined up with. Make sure that the crossmember is square and drill holes for the passenger side. Next unbolt the transfer case case crossmember. Make sure you have a good rolling floorjack under it first! Wrestle your motor into place, slide the trans and TC forward and bolt to motor. When that is secure, jack up the TC crossmember so that it is up against the frame again, drill new holes using the crossmember as your template. There you go, done. Be careful to pay attention inside the cab. You may want to remove your high hump while you are doing this. You will also probably need to have your driveshafts reworked.

jwhitfield · 07-23-2003, 01:08 PM

breeh,

Thanks for that info! A good explaination is all that was needed.

DMAN · 08-15-2003, 12:19 AM

breeh,are you still able to use the small block fan shroud when you do the swap as you described?

**breeh** · 08-15-2003, 01:20 AM

DMAN, I used a factory 2wd big block fan and fan shroud. With the 2" slide forward it puts it in just the right position.

DMAN · 09-02-2003, 03:13 PM

Will the oil pan clear the front diff., or do you need to install a lift kit?
DMAN

**MJN** · 09-02-2003, 07:50 PM

heres what my brother did on his '72 gmc, moved crossmembers ahead one inch, got custom driveshafts (for lift), and fired it up. he put a 454 and four speed in while it was stock height and had no problems just some electrical but that was expected on that truck. Other than that everything fit and worked good he also had to get a custom clutch linkage to fit. We got this info from a guy locally that had done two blazers with 454's.

07-22-2003, 05:35 PM	#1
jwhitfield Registered User Join Date: Apr 2003 Location: Temecula, CA Posts: 56	Another 4x BB swap thread I figured that I set this up as a new thread, maybe it will get more response. There seems to be several of us planning a BB swap. As I've said in the past, my original thought was that the job would be relatively simple. I too thought the 4x4s came with BBs. I've since learned otherwise. There seems to be two trains of thought out there. 1. You don't need to move anything forward, but everything is a tight fit. Some minor grinding and love tapping. 2. Move everything forward 2-2.5 inches. I have yet to start my project, so I haven't got a good look at the components and crossmembers. My questions are with respect to the relocating of the driveline. When you say move everything forward I'm assuming that means engine, tranny and transfercase. How is this done exactly? Is there enough space on the various crossmembers and supports to drill another set of holes or do you have to move those as well? How about moving things 1", is that a good compromise? Sorry for the length here, but if I take on this project, I'd like to get it done in my life time. The more I know up front, the better prepared I'll be to make the decision....

07-22-2003, 05:45 PM	#2
NAPCO ken Registered User Join Date: Aug 2001 Location: anaheim, ca Posts: 187	What year are you working on? I have a Chev 454 in my '60 GMC Suburban 4x4. __________________ ken '58 Chev NAPCO 4x4 short '60 GMC Suburban 4x4, restored '60 GMC 3/4T stepside 4x4 '64 GMC Suburban 4x4, restored '90 Chev Suburban 4x4, dually, ZZ502 '77 GMC Suburban 4x4, one ton axles, 12" lift, 39.5"s '88 Chevy crewcab dually 4x4, 10" lift, 42"s (x6!) '03 Jeep Wrangler Rubicon '79 Chev 3/4 Suburban 4x4, 400-400-203

07-23-2003, 10:50 AM	#4
NAPCO ken Registered User Join Date: Aug 2001 Location: anaheim, ca Posts: 187	I believe that in '72 you could have gotten the 402 as an optional motor in 4x4s. Shouldn't be that much work to install a big block. __________________ ken '58 Chev NAPCO 4x4 short '60 GMC Suburban 4x4, restored '60 GMC 3/4T stepside 4x4 '64 GMC Suburban 4x4, restored '90 Chev Suburban 4x4, dually, ZZ502 '77 GMC Suburban 4x4, one ton axles, 12" lift, 39.5"s '88 Chevy crewcab dually 4x4, 10" lift, 42"s (x6!) '03 Jeep Wrangler Rubicon '79 Chev 3/4 Suburban 4x4, 400-400-203

07-23-2003, 12:48 PM	#6
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	There was no big block option in 4x4's from 67-72. I chose to move "everything" forward 2". It is really not that big of deal to do. The most difficult part is figuring out where to redrill the holes for the torque bracket which hangs off of the side of the transfer case. I am not sure what limiting yourself to a 1" move is going to accomplish. As long as you are redrilling, you might as well go the 2". Basically, unbolt engine crossmember. slide it forward. On the driver's side there is an existing set of holes that I lined up with. Make sure that the crossmember is square and drill holes for the passenger side. Next unbolt the transfer case case crossmember. Make sure you have a good rolling floorjack under it first! Wrestle your motor into place, slide the trans and TC forward and bolt to motor. When that is secure, jack up the TC crossmember so that it is up against the frame again, drill new holes using the crossmember as your template. There you go, done. Be careful to pay attention inside the cab. You may want to remove your high hump while you are doing this. You will also probably need to have your driveshafts reworked. __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

08-15-2003, 12:19 AM	#8
DMAN Registered User Join Date: May 2002 Location: Benicia,Ca. Posts: 128	breeh,are you still able to use the small block fan shroud when you do the swap as you described? __________________ '71 Custom Deluxe K10, shortbed, fleetside.

07-22-2003, 08:14 PM	#3
jwhitfield Registered User Join Date: Apr 2003 Location: Temecula, CA Posts: 56	I have a 72 lwb 4x4. 350/350 The engine is completely tired and I was thinking about swapping in a 396 that I have. I though it was going to be easy, but seems as though it's going to be another high dollar/time project....

07-23-2003, 11:05 AM	#5
jwhitfield Registered User Join Date: Apr 2003 Location: Temecula, CA Posts: 56	Myself, I don't know, but many of the board members have said that BBs didn't come in the 4x4s. I do know that I have not been able to find any listing for motor mount stands. Guess I just have to dive in and see for myself....

07-23-2003, 01:08 PM	#7
jwhitfield Registered User Join Date: Apr 2003 Location: Temecula, CA Posts: 56	breeh, Thanks for that info! A good explaination is all that was needed.

08-15-2003, 01:20 AM	#9
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	DMAN, I used a factory 2wd big block fan and fan shroud. With the 2" slide forward it puts it in just the right position. __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

09-02-2003, 03:13 PM	#10
DMAN Registered User Join Date: May 2002 Location: Benicia,Ca. Posts: 128	Will the oil pan clear the front diff., or do you need to install a lift kit? DMAN __________________ '71 Custom Deluxe K10, shortbed, fleetside.

09-02-2003, 07:50 PM	#11
MJN Registered User Join Date: Feb 2000 Location: Maquoketa, Ia/ Orr, Mn Posts: 2,966	heres what my brother did on his '72 gmc, moved crossmembers ahead one inch, got custom driveshafts (for lift), and fired it up. he put a 454 and four speed in while it was stock height and had no problems just some electrical but that was expected on that truck. Other than that everything fit and worked good he also had to get a custom clutch linkage to fit. We got this info from a guy locally that had done two blazers with 454's.



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.