BB install ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Long Roof · 08-10-2007, 07:56 PM

I just purchased a 72 Jimmy 4x4 with a trashed SB 350 in it. I have a 76 454 that I know runs great and was wondering what kind of problems am I going to run into if I were to try installing this. The Jimmy has AC, PS, PB, HEI and a 350 Auto tranny. The current SB has headers so I would like to use headers on the BB. Can I use the SB engine mounts? The Jimmy is lifted, but there is no body lift. Here are some pics.

1969k10stepside · 08-10-2007, 08:27 PM

You'll probably discover clearance issues concerning the valve covers,the distributor,and the firewall..No 2 big block into 4wd installs are the same.Different valve covers,engine mounts,and even body mounts play a role.
You can avoid some of the clearance issues by moving the motor forward,but then you also have to move the tranny and t-case and crossmembers forward meaning longer rear and shorter front driveshafts too...Some cut some of the firewall out for clearance,and then some add a body lift..In some cases some frame has to be removed due to certain headers..I hope this helps.There is nothing like a big block 4wd but I just keep my trucks small block powered because I hate body lifts and firewall mods,and also to cheap to get different driveshafts ....

Long Roof · 08-10-2007, 09:02 PM

So is the engine set further back in a 4x4 verses a 2wd? Wish it were as simple as I thought it would be.

Aaron

Riddick · 08-10-2007, 10:10 PM

If you move the engine crossmember forward 1.5 inches that will clear up you clearance issues with the firewall but smallblock fan shroud will not work I know the front driveshaft has a slip yolk on it does the rear ? i am pretty sure it does you might have to modify the driveshafts this is not all that expensive and it will really be worth it the Big Block will absolutely rock

1969k10stepside · 08-10-2007, 10:52 PM

Yes,the motor was set back farther on the 4wds for differential clearance.

72cheyennesuper20 · 08-11-2007, 11:49 AM

Thats a good looking jimmy. I think the 454 is a good idea.

08-10-2007, 07:56 PM	#1
Long Roof Old School, New Style Join Date: Jun 2005 Location: Monroeville, Ohio Posts: 790	BB install ? I just purchased a 72 Jimmy 4x4 with a trashed SB 350 in it. I have a 76 454 that I know runs great and was wondering what kind of problems am I going to run into if I were to try installing this. The Jimmy has AC, PS, PB, HEI and a 350 Auto tranny. The current SB has headers so I would like to use headers on the BB. Can I use the SB engine mounts? The Jimmy is lifted, but there is no body lift. Here are some pics. Attached Images __________________ The Good: - 72 GMC Jimmy 4x4 - 307 cid / 350 th - 70 Chevy Suburban 1/2T 2wd - 454 cid /400 th - 96 Chevy Impala SS - mainly stock - 98 Chevy Tahoe LT 4x4 - all stock The Bad: - 86 Chevy Suburban 1/2T 4x4 - winter beater The Ugly: - 72 Chevy Suburban 1/2T 2wd - parts truck

08-10-2007, 08:27 PM	#2
1969k10stepside Registered User Join Date: Mar 2006 Location: USA Posts: 21,019	Re: BB install ? You'll probably discover clearance issues concerning the valve covers,the distributor,and the firewall..No 2 big block into 4wd installs are the same.Different valve covers,engine mounts,and even body mounts play a role. You can avoid some of the clearance issues by moving the motor forward,but then you also have to move the tranny and t-case and crossmembers forward meaning longer rear and shorter front driveshafts too...Some cut some of the firewall out for clearance,and then some add a body lift..In some cases some frame has to be removed due to certain headers..I hope this helps.There is nothing like a big block 4wd but I just keep my trucks small block powered because I hate body lifts and firewall mods,and also to cheap to get different driveshafts ....

08-10-2007, 09:02 PM	#3
Long Roof Old School, New Style Join Date: Jun 2005 Location: Monroeville, Ohio Posts: 790	Re: BB install ? So is the engine set further back in a 4x4 verses a 2wd? Wish it were as simple as I thought it would be. Aaron __________________ The Good: - 72 GMC Jimmy 4x4 - 307 cid / 350 th - 70 Chevy Suburban 1/2T 2wd - 454 cid /400 th - 96 Chevy Impala SS - mainly stock - 98 Chevy Tahoe LT 4x4 - all stock The Bad: - 86 Chevy Suburban 1/2T 4x4 - winter beater The Ugly: - 72 Chevy Suburban 1/2T 2wd - parts truck

08-10-2007, 10:10 PM	#4
Riddick Registered User Join Date: Feb 2006 Location: Omaha Ne Posts: 13	Re: BB install ? If you move the engine crossmember forward 1.5 inches that will clear up you clearance issues with the firewall but smallblock fan shroud will not work I know the front driveshaft has a slip yolk on it does the rear ? i am pretty sure it does you might have to modify the driveshafts this is not all that expensive and it will really be worth it the Big Block will absolutely rock

08-10-2007, 10:52 PM	#5
1969k10stepside Registered User Join Date: Mar 2006 Location: USA Posts: 21,019	Re: BB install ? Yes,the motor was set back farther on the 4wds for differential clearance.

08-11-2007, 11:49 AM	#6
72cheyennesuper20 Registered User Join Date: May 2005 Location: Portland, OR. Posts: 414	Re: BB install ? Thats a good looking jimmy. I think the 454 is a good idea.



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