Big block troubles - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**MJN** · 08-04-2002, 11:11 PM

Trying to fit a 454 in a '72 GMC k/2500. Originally had a 350 but am implanting a big block. Tried to put the motor in and the valve covers hit the fire wall, and the motor mounts didn't even get close enough to bolt down. Does it need a big block crossmember or what?

HvyChevy454 · 08-04-2002, 11:15 PM

i went froma 350 to a 454 in my 72. i got the 69-71 BB mounts, at he time didnt know the difference, measured drilled new holes so that the motor would be far enough ahead to have ample clearance for teh covers. didnt leve much room for the fanthough but works well nonetheless

*racedvl* · 08-04-2002, 11:22 PM

4X4's never came with big blocks. So there is no big block cross member. I know some members have fabbed BB's into their 4x4's. They would be the ones to ask.

HvyChevy454 · 08-04-2002, 11:38 PM

actually here is a post on the subject
http://67-72chevytrucks.com/vboard/s...threadid=19191

**Desert Rat** · 08-05-2002, 12:26 AM

the motor needs to be moved foward in 4x4's and massaging of firewall for a hei if you dont move far enough foward,

trukman1 · 08-05-2002, 06:04 AM

I did this swap before and communicated with lots of guys who did it. The SB mounts fit the BB fine. No problems on oil pans that I know of. The engine is usually moved forward 1 3/4" to clear everything (including HEI) as a minimum. Some guys have gone as far as 3" but I don't recommend it since it causes fan to radiator clearance issues. Most run short water pump system. BTW, you can use your existing x-member too. If your have any specific questions send me an e-mail and I'll try to help as much as I can. Gary

**MJN** · 08-05-2002, 08:05 PM

According to the parts department guy at the local dealer all it needs is the small pads that the mounts rest on. Otherwise it should fit. Thanks

**68SWB4x4** · 08-05-2002, 08:25 PM

you could install a body lift for clearance

08-04-2002, 11:11 PM	#1
MJN Registered User Join Date: Feb 2000 Location: Maquoketa, Ia/ Orr, Mn Posts: 3,051	Big block troubles Trying to fit a 454 in a '72 GMC k/2500. Originally had a 350 but am implanting a big block. Tried to put the motor in and the valve covers hit the fire wall, and the motor mounts didn't even get close enough to bolt down. Does it need a big block crossmember or what?

08-04-2002, 11:15 PM	#2
HvyChevy454 Slowly getting CRSS... Join Date: Jul 2001 Location: Lutz, Florida Posts: 656	i went froma 350 to a 454 in my 72. i got the 69-71 BB mounts, at he time didnt know the difference, measured drilled new holes so that the motor would be far enough ahead to have ample clearance for teh covers. didnt leve much room for the fanthough but works well nonetheless __________________ -Nic Lutz, Fl My Team Website The Heavy Chevy Website ------------------ 72 Cheyenne 10 LWB GM 12-bolt 3.08 w/ Auburn Posi 91 454 Edel Performer RPM Intake 750 cfm carb Comp Cam 268/.495 Hedman Headers Dual 3'' Exhaust 71 Cheyenne 20 4x4 Fact. A/C PS PB Tilt Currently in the works... Speak Softly and Carry A Big Block... There is No replacement for Displacement... "If everything seems under control, you're just not going fast enough." - Mario Andretti

08-04-2002, 11:38 PM	#4
HvyChevy454 Slowly getting CRSS... Join Date: Jul 2001 Location: Lutz, Florida Posts: 656	actually here is a post on the subject http://67-72chevytrucks.com/vboard/s...threadid=19191 __________________ -Nic Lutz, Fl My Team Website The Heavy Chevy Website ------------------ 72 Cheyenne 10 LWB GM 12-bolt 3.08 w/ Auburn Posi 91 454 Edel Performer RPM Intake 750 cfm carb Comp Cam 268/.495 Hedman Headers Dual 3'' Exhaust 71 Cheyenne 20 4x4 Fact. A/C PS PB Tilt Currently in the works... Speak Softly and Carry A Big Block... There is No replacement for Displacement... "If everything seems under control, you're just not going fast enough." - Mario Andretti

08-05-2002, 08:25 PM	#8
68SWB4x4 Strongman Garage Join Date: Apr 2000 Location: Salinas, CA Posts: 10,241	you could install a body lift for clearance __________________ Kalle 68 GMC Suburban 1500 4x4 SOLD 69 Pontiac Lemans 99 Silverado 4.8 5 speed ECSB [ Facebook Instagram Subscribe on YOUTUBE

08-04-2002, 11:22 PM	#3
racedvl Account Suspended Join Date: Jan 2000 Location: Woodstock, IL Posts: 7,020	4X4's never came with big blocks. So there is no big block cross member. I know some members have fabbed BB's into their 4x4's. They would be the ones to ask.

08-05-2002, 12:26 AM	#5
Desert Rat Senior Member Join Date: Dec 1999 Location: Darrington, Washington Posts: 3,963	the motor needs to be moved foward in 4x4's and massaging of firewall for a hei if you dont move far enough foward,

08-05-2002, 06:04 AM	#6
trukman1 Registered User Join Date: Apr 2001 Location: Beavercreek, Ohio 45431 Posts: 737	I did this swap before and communicated with lots of guys who did it. The SB mounts fit the BB fine. No problems on oil pans that I know of. The engine is usually moved forward 1 3/4" to clear everything (including HEI) as a minimum. Some guys have gone as far as 3" but I don't recommend it since it causes fan to radiator clearance issues. Most run short water pump system. BTW, you can use your existing x-member too. If your have any specific questions send me an e-mail and I'll try to help as much as I can. Gary

08-05-2002, 08:05 PM	#7
MJN Registered User Join Date: Feb 2000 Location: Maquoketa, Ia/ Orr, Mn Posts: 3,051	According to the parts department guy at the local dealer all it needs is the small pads that the mounts rest on. Otherwise it should fit. Thanks



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