67-72 BigBlock 4x4s! Pos pics info here.

[gmc 2500 4x4]

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[Todd Johnson]

I have two big block chevys (1968 2"s forward + 1970 stock location). If your going to make the swap it's easier to move the engine 2"s forward. You can install a 700R behind and the lengthen your transfer case shaft. The advantages are it's easier to reach transmission bolts, more room for valve covers, and HEI fits easier. Stock location on every truck will be a little different but you can put a 454 in the same place as your previous motor. Modifications are miner to make it work. The added weight will make the truck bounce more in front so I would suggest installing a rear gas tank to help balance the truck back out.

[gmc 2500 4x4]

is there an adapter plate used to mate a 402 to 350 bell housing?

[72chevyk10]

Originally Posted by gmc 2500 4x4

is there an adapter plate used to mate a 402 to 350 bell housing?

nope. chevys are all the same up till the ls engines

[gmc 2500 4x4]

good thread here, im gonna take the plunge and drop a 402 in my '69 gmc..sumthin bout a BB!

[waybad]

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[zeusflash]

Heres mine.....still needs work though!

[Rocketman72]

I installed a bbc in my 72 K5 about 12 years ago, left the cross member in the stock sbc location, I saw the extra holes in the frame and should have moved the cross member but I didn't. I was worried about what other mods I would have to do such as, shift linkage, drive shafts, transfer case mount hole, ect.

After reading this thread, I think I'm going to go with a 700R4 and move the engine forward. I can always lengthen the linkage and I think there's plenty of room for the 4wh shifter to move a little if necessary.

I used the stock bbc manifolds and some grinding was required and I also worked on the firewall behind the HEI dist. I wish I had not damaged my freshly painted firewall but, I did. I also had to do some work behind the valve covers also needed some clearance.

[Jsposito]

Great advice on this post. Should be very helpful. However, I see some of you are using the sbc mounts in the stock location and others are using the bbc mounts. I have both available. If I'm going to put the big block in the stock small block location what mounts should I go with?

[turp mcspray]

Since there never was a big block available in a 4x4, there is only the stock small block engine mount to use. The 2 wd mounts are completely different.

[Gobuffalo]

496, Edelbrock aluminum heads, Comp hydraulic roller cam, TH400, NP205, 14 bolt rear, Dana 60 front, 4.56s.
1970 Suburban. Got a long way to go.

[Gobuffalo]

Got some more done.
3" stainless exhaust, Magnaflow mufflers, new drive lines, new shocks.

[2 Far Gone]

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[CUSTOM/10]

Was that an exhaust kit, or did you just buy pipe, fittings and weld them up?
I'm planning on doing an exhaust on mine soon, very similar to yours but 2-1/2 in.

Gary

[Gobuffalo]

I used a Flowmaster 3", 409 stainless builders kit and Magnaflow 3", 409 stainless mufflers. The Flowmaster kit is about $350.00 from Summit. The hardest part was the flanges to bolt the exhaust to the headers. I could not find anything made of 409 stainless. I ended up using 3/8" steel flanges. You have to use a special welding rod called 309L to weld mild steel to 409 stainless.
I could not find any premade systems made of anything bigger than 2" for a 4x4. Lots of stuff for 2 wheel drive. The kit had almost enough parts for the complete system. I had to buy 1 extra 45* bend to finish the tail pipes.

[CUSTOM/10]

Your exhaust system looks & sounds like what I have planned on doing right down to the Magnaflow mufflers, with the exception of being 2-1/2 in. I have a 383 stroker built for more low end - mid range RPM. I have Headmen SS elite headers with 3" ball end flanges so I'll have to use a reducer.

Have you completed it yet ? Where did / are you ending it, in front of the tires, behind or out the back ?

Gary

[Gobuffalo]

I can't finish till the body and the tires and wheels are on.
I'm running it out the side behind the tire. I would like to run it to the very back corners but being a Suburban, the spare tire well is in the way. I thought about removing it because a 37' tire won't fit in it. But I'm turning it into a storage compartment instead.

[CUSTOM/10]

I believe I'm going to run mine out the side just behind the tires. Mines a SWB, do you think the kit would have enough fittings for a SWB ? Does it come with everything to run it up and over the axle ?
Not sure if I'll have the room for the X pipe being swb, hope so !
Gary

[Gobuffalo]

It might be enough.
One of my headers comes out at a 45 the straight down and it takes a lot to go over the T-case.

[Rocketman72]

Originally Posted by Jsposito

Great advice on this post. Should be very helpful. However, I see some of you are using the sbc mounts in the stock location and others are using the bbc mounts. I have both available. If I'm going to put the big block in the stock small block location what mounts should I go with?

I think you can use the bb mounts by bolting them to your existing cross member. This should raise the engine slightly, increase your drive angle and make a little more room for your exhaust manifolds or headers if you should decide to use them.

If you are going into a K5 with your big block or if you don't have enough clearance I would suggest moving the cross member forward rather than beating up the firewall to make room. It's not very pretty after taking a sludge hammer to your firewall.

[Gobuffalo]

I guess I should pay attention to what I'm typing!
The right header comes out at a 45* angle. The left side points straight down. When I was done, I had I extra 90* bend and was short 1 45.

The big block stands won't bolt onto the factory small block 4x4 crossmember without modifying them.
I used all small block mounts and cross members to bolt my big block, TH400/NP205 in. I used the forward most mounting holes in the frame (I compared a 2 wheel drive, big block truck frame to mine). Even though I moved the engine forward to the factory big block position, I had to move the trans cross member back 1". Which means the t-case shifter didn't line up in the original hole, so it got a "custom" bend.

[Gobuffalo]

Right side.

[Gobuffalo]

Trans and t-case.

[Jsposito]

Finally getting around to posting an update here. Got the 402 in and running. All the info in this thread was spot on. It sure is a tight fit but a little massaging on the firewall and small notch on the passenger frame rail for the header and she slid right in on the factory motor mounts. If this truck wasn't my daily driver, moving the motor forward 1.5" like suggested would definitely be the way to go but all is good like this!

[70K5AK]

Hey guys! I'm swapping a tired 350 out for a 396, in addition to swapping the TH350 with a TH400, all with NP205 T-cases. I got a new-to-me TH400 with a 205 already mated. From what I have researched and measured (based on my previous TH350/NP205 adapter setup vs my new TH400/NP205 setup), I'm going to add about 3" of drivetrain length due to the trans swap.

I'd like to leave my T-Case in the stock position so I don't have to cut driveshafts, move shifter hole, etc and just move the engine crossmember forward the approximate 3". I don't want to do a body lift. Do you think that would get me the adequate clearance from the firewall? Also, has anyone gotten away with this running stock-ish big block manifolds vs headers without notching the frame? Any other gotchas? Thanks a lot, great thread! Dave