Big block question!!!

[Virginia72SWB4X4]

I'm pulling together parts to put a BB in a 72 SWB 4x4.
A buddy of mine has a late model (95) 454 he said I could have. Needs rebuilding
A question is are the motor mount locations and acessory mounting locations the same on a later model BB as they were on the old? What about exhaust headers? Would they be the same as well?

Thanks to all!

[williars]

The mounting position on the block is the same. Just ensure you use the BBC motor and frame mounts. It will save a mountain of time later, like when you try to mount the headers. I will leave the header question to the others...I lost that battle. I purchased headers that were supposed to fit and spent another 100 bucks having them fabricated so they would. I'm kind of interested in the other answers myself. (Part numbers maybe)

[Virginia72SWB4X4]

Williars,

Thanks So you say make sure you use 72 BB towers and motor mounts?
If I'm not mistaken the SB 4x4 uses the same towers just the BB motor mount itself is differnet

Gary

[williars]

Gary,

You could very well be correct. Is 72 the year they changed the type of mounts? I will sit back and let the more knowing members answer. Mine was a 69 that I put a 454 into. I am almost certain the mounts is why everything else was wrong. Was one long weekend trying to get everthing to fit. - Ryan

[Faster_than_you]

I couldnt tell you for sure, I just thought to say that I was lucky enough that the owner before me had switched from a 350 to a 396 in my 71, my 454 just slipped right in.

[john]

BB exhaust manifolds will not fit with SB towers. John

[Virginia72SWB4X4]

John,

Do you mean BB stock exhaust manifolds have a clearance issue with SB mount/towers?

[Classic Heartbeat]

I guess that everyone missed the fact that this is a 4x4.... GM did not install Big Blocks in 4X4s between 1967 to 1972. You install the engine on the existing mount and either dent the firewall or install a 2" body lift so that the valve covers will fit. Then you cut the top of the frame to fit headers, or the top of the mount for the exhaust manifolds. Use small block motor mounts. WES www.ClassicHeartbeat.com

[Virginia72SWB4X4]

You're right Wes. Bill gave me the info to move the crossmember and mounts forward 2" for clearance.

[jhow66]

We used the SB towers & mounts that were in my son's (orangeuavol) 72 Blazer and cut a hole in driver side firewall(will weld in a small box). Used 72 M.C. BB exhaust manifolds which cleared the towers without cutting. (couple of pic.)

[jhow66]

#2

[Yukon Jack]

Here's a link to my progress on my BB swap. Body should be going on the frame in a week or two.

[Javy]

If you rebuild this '95 454 to close to stock specs, I may be wrong but a '95 454 only puts out around 280 hp.
In 1988 I bought a 1 ton dually with a 454 and it only put out
about 275 hp and 7 mpg.
Could be in California smog emissions limited hp.

Just my 1 cent

[Virginia72SWB4X4]

Jav,

I have the same concern. The later model lower compressio engine does have the kick in the paints the oldr does.
I figured I may address this when i decide how much rebuilding the engine needs. MAybe I can rebuild forbetter performance.

[hllblly1972gmc]

I replied to another thread about this, I may be all wrong or just doing to much but this it what i did, I just copied this from the other one.

I have a 1972 gmc 1/2 ton 4x4 short bed. Still building, but should be done in the next ten years I think. I built a 520 CI BBC. For headers I have the Hookers. They fit good so far, but may run into some issues around the transfer case. I did trim the frame a bit. I am using Merlin heads, so the exhaust ports are a little higher than stock heads, about a 1/4 inch or so. I moved my engine back 2 1/2 inches. I cut out my firewall and fabbed a new one. The firewall sits about 1/4 inch from the plastic heater box inside the cab. I built a new crossmember, and am using big block mounts. I lifted the body 1 1/2 inches, i cut three inch blocks in half because i didnt want too much lift, already have a six inch suspension lift. As far as the question about the clutch linkage, I ground the old bracket off the frame and moved it so it would match the pivot ball. Then made up new rods for the linkage to adjust for length, also due to the firewall change, my clutch linkage off the pedal is also different, it goes through the floor about two inches further to the driverside. I use tall merlin valve covers and have no clearance issues with the brake booster or heater box, this is a non a/c cab. Maybe this will help someone. I am going to alot of work but I want it to be right. If anyone has any questions of anything I did, or maybe something I did wrong just reply to this. Im not done yet so.... you never know.

I had the BBC towers off a two wheel drive, was going to try to modify them, thought they looked like crap so I built my own. Ill try to get some pics of what I did, just got to but a camera.