4x4 1970 blazer big block conversion

[72gmguy]

Hey everyone, I am new to the message board and am sure this has been discussed before but I want to convert a 70 4x4 blazer I just purchased to a big block. I cant seem to find mounts for the conversion. anyone selling mounts for a 4x4 with a big block? I also have a 1972 blazer cst, 1970 4x4 suburban project with a 6 inch lift, 1972 suburban 2wd with a factory 402 and front and rear a/c, and a 1972 c30 ramptruck. Thanks in advance

[Gary 70 Jimmy]

welcome from Ohio I need to no the same thing I have a 69 blazer 4x4 I want to put a 396 in it.

[72gmguy]

thanks for the tip. as I find out what we need I'll let you and the rest of the forum know.

[Burt4x4]

if you are refering to the engine mounts a BBC will bolt up to a SBC engine mount, they are the same, so is the bellhousing bolt pattern.
I put a 454 in my K5.
I did it different than most, I used a 73+4x4SBC engine crossmember & frame horns..then modified that to fi ORD engine crossmember.
It's a very tight fit but it doesn't touch:


Also ORD HP engine mounts. My 454 does NOT move when rappin the throttle, the whole front of the truck does


Here is the first crossmember from a 73SBC4x4..the x-member is 3piece = 2 frame horns + 1crossmember.
The crossmember developed a crack shorlty after I got the 454 fired up so I swapped it for he ORD one.
Good Luck
Burt

[Burt4x4]

BTW this is were I got the idea to use the 73+ SBC 4x4 mounts:


The pic on the bottom left is the frame horn. It is NOT easy to get them into the frame like in the photo. I had to make two cuts in the mount to bend down the top lip of the mount making it shorter to fit into the frame. On the pass side there are two holes that line up but you have to drill all the other holes to make it work.

If you just want to get a BBC in there then use your SBC mounts, you may need to adjust your firewall for valve cover clerance and get a bigger 4core radiator.

[bouncytruck]

Isn't some modifications to the firewall required for a BBC too?

[72gmguy]

Originally Posted by Burt4x4

BTW this is were I got the idea to use the 73+ SBC 4x4 mounts:


The pic on the bottom left is the frame horn. It is NOT easy to get them into the frame like in the photo. I had to make two cuts in the mount to bend down the top lip of the mount making it shorter to fit into the frame. On the pass side there are two holes that line up but you have to drill all the other holes to make it work.

If you just want to get a BBC in there then use your SBC mounts, you may need to adjust your firewall for valve cover clerance and get a bigger 4core radiator.

Thanks for the pics, I checked out that ord site. They have some great product for us. Did you have to use custom headers or did you squeeze a set of pre made tubes in? It looks like you have a sweet project going yourself, hope mine turns out half as good.

[Long Roof]

Most every BB into a blazer I have seen has had firewall modifications. The valve covers typically hit so something must be done. The reason for this I have been told is that GM set the engine and trans further back (1 1/2" or so) to clear the front axle. Three solutions would be hammer the firewall, move the engine forward and install a spring lift or install a body lift.

[AJs72K5]

These guys have pretty much covered it. I don't know that anyone has tried a DIY4X engine crossmember yet on a K5 with a BBC, but I have one on the way. It'll be a while before I'm ready to drop the engine back in though.

[vtblazer]

Originally Posted by 72gmguy

Hey everyone, I am new to the message board and am sure this has been discussed before but I want to convert a 70 4x4 blazer I just purchased to a big block. I cant seem to find mounts for the conversion. anyone selling mounts for a 4x4 with a big block? I also have a 1972 blazer cst, 1970 4x4 suburban project with a 6 inch lift, 1972 suburban 2wd with a factory 402 and front and rear a/c, and a 1972 c30 ramptruck. Thanks in advance

Welcome to the board, always good to see another member from the NE.

What's the rest of the drive train going to be?
Anything different than stock?

Have you checked out CK5? Tons of info about this over there too.

[Burt4x4]

"Did you have to use custom headers or did you squeeze a set of pre made tubes in? "

The heders are Thorley 304-Y 2x4 454 Chevy Truck

They don't fit as well as other headers, pass side is way high and tight to the frame and the diver side is way low waiting to get SMACKED by a rock er somtin..

The Tri-Y design is only good for RPM levels upto 4500-5000..after that the power falls on it's face..I had my K5 dyno tested and tuned so I have the graph the shows the drop off.
For me the power gains at low RPM are worth it..I built my K5 for low RPM stump pulling power
do a search for BBC and you'll find a post with lost of pics and talk about this swap

[Yukon Jack]

Here's a very good thread linky on the challenges some of us have faced when afflicted with the BBC disease.

[72gmguy]

Originally Posted by vtblazer

Welcome to the board, always good to see another member from the NE.

What's the rest of the drive train going to be?
Anything different than stock?

Have you checked out CK5? Tons of info about this over there too.

Thanks for the welcome, right now the truck is a 3 speed manual but I intend on a 465 in its place. I will also be putting a 4 inch lift and the 35 inch mt tires that are currently on my 70 sub on the blazer and buying new 37's to go on the sub with a 6 in lift.

I have not checked out the ck5 site but I will now. thanks

[72gmguy]

thanks for the link, you guys are a huge help

[doug1]

I am in the same prediciment:
I am trying to put a 402 in a 70 blazer & require different mounts maybe? It is bolted in with small block mounts and sits too far back and not high enough any suggestions ? Somebody must make a conversion kit for this application?

[vtblazer]

Originally Posted by doug1

I am in the same prediciment:
I am trying to put a 402 in a 70 blazer & require different mounts maybe? It is bolted in with small block mounts and sits too far back and not high enough any suggestions ? Somebody must make a conversion kit for this application?

The link Yukon posted is a great thread, the answer isn't as simple as just buying a conversion kit.

http://67-72chevytrucks.com/vboard/s...d.php?t=263273