72 4x4 BB swap?

[72 k15]

I found a nice rebuild 402 for a good price Wondering how hard it is to swap a big block in i did some reading and read it doesn't fit properly?

[68is4me]

I am sure that it can be done. I know the 4x4's never came with a BB, so I think the only major hurdle would be the engine stands, and maybe an oil pan. I have seen people on this forum add the BB to the 4x4 so I know it can be done.

[72 k15]

Originally Posted by 68is4me

I am sure that it can be done. I know the 4x4's never came with a BB, so I think the only major hurdle would be the engine stands, and maybe an oil pan. I have seen people on this forum add the BB to the 4x4 so I know it can be done.

I actually don’t mind the 350 but it’s burning oil like a 2 stroke and most likely has 300k+ miles and I’d have so sell my extra engine I’m trading for instead of just trading for the rebuilt 402. So I would like to put the 402 in but no idea on figment anyone that has done this help would be appreciated.

[cypressbog]

I bought a 71 4x4 half-ton truck 17 years ago that had a BB prior to my purchase. The firewall was pounded on to make room for the distributor and the engine cradle was seriously cut to make way for the oil pan. It was upgraded to 8 lug axles from a mid-70's Chevy 3/4 ton truck.

If you're installing in a 1/2 ton with factory running gear, I'd worry about if the axles, drive shafts, and U-joints are strong enough.

[72 k15]

Not to worried on drive train strength only be 350ish go 400 tq

[Jeff's bowtie's]

I've done this swap before. I moved the engine mounts 2" to the front of the frame a the trans crossmember as well to make room for the heads and hei distributor and then used a 2wd shroud but the you have to resize your driveshafts but then the engine looks like it belongs in the truck without beating the crap out of the firewall

[8cuda]

Did you have to cut the floor for your shifter(s)?
Is this method for installing the a BB
1. Move motor mounts 2 inch forward
2. Move the transmission and transfer case mount 2 inch forward
2a. for manual trans, does the effect the z bar?
3. Increase the rear drive shaft
4. Decrease the front drive shaft

[Jeff's bowtie's]

I used a high hump from a 2wd 4 speed and cut the hole for the transfer shifter and this makes up for the 2" moved forward and yes this is for a big block conversion and yes it does effect the drive shaft lengths and just move the Z-bar frame bracket forward as well

[landarts]

I have a 402 big block in my 72 GMC 4x4. The firewall has not been modified, back of valve covers are close to firewall and distributor really close also. Does not look like anything was moved forward. If you need a measurement let me know.