454 Swap, out with the 350 in with more power!

I know you can make plenty of horsepower with a small block. I have done it several times. Bolt on some AFR heads, add a Voodoo cam and yes, you will have more horsepower then a stock big block. But… you can do those same mods to a big block like a 454 and have even more power. The small blocks just don’t have the same low end power or sound.

I want a big block, so its getting a big block. 

She isn’t much to look at, but that is a moderately good running SBC in there. Check out the wood beside the radiator. That the battery box!

There isn’t much too exciting about pulling out a SBC.

You unhook the throttle linkage and kick down if you have one.
Unhook the vacuum line from the tranny.
I remove the distributor so I don’t hit the fire wall and break it.
Remove the radiator hoses.
I removed the radiator instead of removing the front accessories.
Unhook the power steering lines.
Unhook any gauges like your oil pressure gauge.
Unhook the exhaust from the manifolds.
Unhook the starter after unhooking the battery
and then unhook the wires from the alternator.

Did I miss anything?

Oh, you finally unbolt the two long bolts from the motor mounts and then the 6 bolts attaching the tranny to the block. If your an auto, you need to remove the fly wheel cover so the torque convert will come out still attached to the flywheel.

Out is the easy part. That really wont take you very long. It might sound like a lot but most of that is a few clips or hose clamps.

I ran into an issue with the hoist not being tall enough. It’s pretty old and might be low on fluid. I bought it close to 10 years ago used for $100. I had to take the front wheels off the truck and set the front hubs on blocks of wood to get it as low as possible but high enough to clear the legs on the lift.  This still did not give me enough height. Thankfully, the truck is getting repainted.

I climbed into the engine compartment and lifted and pushed and cussed and shoved on that engine till it slide over the core support and out of the engine compartment. It really didn’t do any damage to the core support. Just a few more scratches. I will repaint the core when I do the body.

Since the motor was out I decided to clean up the frame and the firewall. The inner fenders and core support will be done when I replace the fenders. If for some reason this used 454 runs good I will probably leave it in for a while and thus, I should clean up behind it while I had access.

I loaded the truck onto the trailer and headed to the car wash. I love having a lift and large shop doors. Backed the trailer in and pulled the truck up on it right from the lift.

Years of oil leaks do not wash off easy. Spent a good while at the car wash and then used a wire brush to get the rest of the frame so I could paint it. Nothing fancy. I just got a quart of enamel and brushed it on. Remember, I want a driver out of this truck. I don’t want it torn to pieces for a full restoration. Not till the Nova is done and Halie’s truck is done.

clean frame

I sanded down the fire wall up to the factory sealer. I also took the time to grind out some rust and apply a rust converter to it. The next day I added a little body filler to hide it. I did not weld in a new piece of metal. The spot was less then a 1/2 inch big. I then just rattle canned the fire wall satin black. Im not sure how I feel about that. Part of me wanted to strip the fire wall and paint it the right way but that would have added more cost and another week or two to the engine swap. I resisted the urge and stuck with a rattle can.

Take a look at where the steering gear box goes. You can see the finished work on someone else’s repair.  

This truck, like most square body 4×4’s had the frame torn where the gearbox bolted up. Someone had already plated it. I did not like how large the welds were or that they forgot to weld that inside edge. I took the time to grind it a little smoother and finish welding it.

Ok, back to the engine swap

I found a 454 and Th400 on Craigslist in Denver. Not big on going to Denver but I was headed up there to deliver the 46 to its new owner. While we were there, I grabbed the engine and tranny. The tranny is a 2 wheel drive version and wont work in this truck but it will work in my Nova. Everything worked out great. $800 and I had a 454 for this truck and a tranny for the Nova.

I am skeptical about putting a used engine in a truck. It’s not in the budget to rebuild it at this time and I don’t know how I want to build it. I figured it would be good to see how it ran and then decided what to upgrade.

I separated the tranny from the block and moved the clutch from the 350 to the 454. I got a new pilot bearing because I do not believe it to be possible to remove one without trashing it.

Yes, I am actually going to use the old clutch. I think it is almost new. There are no signs of wear or heat marks. It actually does look brand new. It was even perfectly clean. With the way that 350 leaked, it had to be new.

I removed a broken fuel pump from the 454. I broke it trailering it home on a flat bed. I would have replaced it anyway.  I then installed the motor mounts on the freshly painted frame.

Now I have to ramble a little about motor mounts. Starting on the left is a new 350 mount, then a new 454 mount then the 350 mount that was in the truck. I have heard the only different was in the height. Well I placed a straight edge on them and all 3 are the same height. The 454 are not 1 inch taller, they are longer.  As you can see in the picture the 454 are longer. To long to fit the frame. You cannot fit those mounts in this truck. I used the new 350 mounts.  I also checked the position of the holes. They are all the same. All mounts will have the bolt location in the same spot. If there is a difference it will be in the frame and not in the mounts.

I have heard enough times that the 454 are taller that I started measuring. The clam shell on the block side is longer. Its about a half inch longer then the clam shell on the 350. I believe this to the the height difference people are seeing.

Remember the height issue I had on the lift with 350. I knew there was no way to get the 454 over the core support. I ended up buying a new engine hoist from Harbor Freight. Was $179 and lifts about 2 feet higher than the old one. 90 inch lift height. Using that I had no issues getting the 454 over the core.

The motor slid over the 350 mounts and lined up perfectly. That part of the install was one of the easiest I have done.  The hard part came with the tranny. No matter how many times you install an engine, its always different. Some just fall in, others fight every step of the way. This one wasn’t too bad.

For some reason the tranny was rotated slightly and would not line up. I messed with it for about 30 min and then got cleaned up for dinner and church. Figured, I would deal with it later.

The next day I put the truck in neutral and spun the driveline. I put it in gear and tried to turn the drive line. I turned the motor over with a wrench a few times trying to make stuff line up. Eventually it did. No one thing really worked. I just fussed with it for another 30 min and it finally lined up enough to bolt together.

The 454 is in the truck and attached to the tranny.  I want a different exhaust manifold and I need a radiator. I haven’t decided to use the serpentine system on the new 454 or not. I like the idea but HATE the size of the brackets. They look terrible.  I will create another post going over the accessories or add more to this one when I get it worked out.

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Gordon French

Gordon French was born in Wyoming in 1978. He is married to Tiffany French. He has two children Halie and Zac. His first passion of course family with cars coming in a very close second.

8 thoughts on “454 Swap, out with the 350 in with more power!”

  1. I have read your story. Gave me hope. Iam in same process. Doing 79 3/4 ton 4wd chevy. Had a small block 400 originally have a rebuilt 454 want put in but engine mounts was big issue. Until read your story. Thank you for sheading light

  2. Hello
    Great write up on the small block to big block swap.
    I’m in the process of the same swap on a 1987 3/4 ton 4×4
    I’m wondering if you can help me out with the motor mount mystery. I get that the mounts attached to the frame are the same height no matter if it’s bbc or sbc, although we’re they mount to the frame has some differences.
    It’s the clam shells mounted to the block that I’m wondering about. If you set a BBC clam shell and a sbc clam shell side by side on a flat surface do the holes that the through bolt that connect the two halves of the motor mount together line up? Or is this were the height difference happens.
    I’m trying to get enough room for header fitment.
    Any light you can shed on this would be greatly appreciated.

  3. Hey buddy I want to to this to my 91’ Sierra but I was wondering what all you had to do with the computer/Ecu?

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