4wd big block cross member - The 1947 - Present Chevrolet & GMC Truck Message Board Network

69CvyPickup4x · 08-01-2006, 12:15 PM

first off i know the thread is worthless without pics but they will be here asap.. my truck is a 4x and when bought (from PO) came with a 396 bbl, i removed it in favor of a brand new 454 i had, when i pulled the motor out i noticed the cross member was cut right down the center and split apart, there is about a 1" gap. i dont know if the frame is bent also as a result of the cut cross member or if the cross member was cut to be made wider.. i dont know. im lookin for any suggestions i need to start TODAY on it. ANY HELP GREATLY GREATLY APPRECIATED thanks

70rs/ss · 08-01-2006, 01:08 PM

BBC and SBC are the same width, so the BBC can be mounted in the same place as the SBC using the SBC mounts, as for the crossmember being cut, get another one, otherwise the framerails will want to distort with the torq of a BBC.

69CvyPickup4x · 08-01-2006, 03:08 PM

well i had an idea, hoping this will do which i dont see why not; take the cross member out of the truck, bolt the cross member to the motor while its out and weld it back together while its bolted on the mounts and then put it back in the truck and make the necessary adjustments to the frame if need be (drill new holes, pull the rails back together if bent apart a bit because u cant tell with the naked eye)??
hows that sound because finding another 4 wheel drive cross member would be a b**** unless a 73 and up x is used and by then id just build a tubular one or something of the sort.

70rs/ss · 08-01-2006, 04:17 PM

If it is just cut with nothing missing it will work, I'd plate it over the butt weld for strength. Post a pict so we can be sure we are offering the best advice.

**jamie72** · 08-01-2006, 04:25 PM

if it helps there was no 67-72 factory big blocks in 4x4s if you need a new xmeber i know where you can get one or post wtb in the parts board, they are not that hard to find.
good luck.

**Yukon Jack** · 08-01-2006, 05:40 PM

A benefit of using the 73-up crossmember is better engine mounts and you gain oil pan clearance.

Rod · 08-01-2006, 10:36 PM

Thought I'd throw up a pic of what the original style 4x4 engine cross member looks like...67-72 type. Maybe that will help someone. Just a pic I had ...don't have one for sale.

08-01-2006, 12:15 PM	#1
69CvyPickup4x Registered User Join Date: Apr 2006 Location: Bellflower Posts: 79	4wd big block cross member first off i know the thread is worthless without pics but they will be here asap.. my truck is a 4x and when bought (from PO) came with a 396 bbl, i removed it in favor of a brand new 454 i had, when i pulled the motor out i noticed the cross member was cut right down the center and split apart, there is about a 1" gap. i dont know if the frame is bent also as a result of the cut cross member or if the cross member was cut to be made wider.. i dont know. im lookin for any suggestions i need to start TODAY on it. ANY HELP GREATLY GREATLY APPRECIATED thanks

08-01-2006, 01:08 PM	#2
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,270	Re: 4wd big block cross member BBC and SBC are the same width, so the BBC can be mounted in the same place as the SBC using the SBC mounts, as for the crossmember being cut, get another one, otherwise the framerails will want to distort with the torq of a BBC.

08-01-2006, 03:08 PM	#3
69CvyPickup4x Registered User Join Date: Apr 2006 Location: Bellflower Posts: 79	Re: 4wd big block cross member well i had an idea, hoping this will do which i dont see why not; take the cross member out of the truck, bolt the cross member to the motor while its out and weld it back together while its bolted on the mounts and then put it back in the truck and make the necessary adjustments to the frame if need be (drill new holes, pull the rails back together if bent apart a bit because u cant tell with the naked eye)?? hows that sound because finding another 4 wheel drive cross member would be a b**** unless a 73 and up x is used and by then id just build a tubular one or something of the sort.

08-01-2006, 04:17 PM	#4
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,270	Re: 4wd big block cross member If it is just cut with nothing missing it will work, I'd plate it over the butt weld for strength. Post a pict so we can be sure we are offering the best advice.

08-01-2006, 04:25 PM	#5
jamie72 Senior Member Join Date: Apr 2000 Location: madison indiana Posts: 3,836	Re: 4wd big block cross member if it helps there was no 67-72 factory big blocks in 4x4s if you need a new xmeber i know where you can get one or post wtb in the parts board, they are not that hard to find. good luck. __________________ jamie72 72 BB cheyenne -- Restoration getting started.. member #807 http://www.myspace.com/whitetailobsession www.antlertalk.com

08-01-2006, 05:40 PM	#6
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,686	Re: 4wd big block cross member A benefit of using the 73-up crossmember is better engine mounts and you gain oil pan clearance. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

08-01-2006, 10:36 PM	#7
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	Re: 4wd big block cross member Thought I'd throw up a pic of what the original style 4x4 engine cross member looks like...67-72 type. Maybe that will help someone. Just a pic I had ...don't have one for sale. Attached Images __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

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