Tbi 454 swap

[jkeys0218]

I saw a k5 with a 454 in it for sale online today and it got me thinking about that worn out 305 that i have yet to pull from my blazer. I searched a little but didn't find much. Is this a hard swap? I know a 350 will pretty much bolt right in. How much bigger is a 454 than a 350(like length/width/height)? What kind of gas millage could i expect? Would the power be worth the extra gas? Its a toy not a daily driver and the only thing i ever tow is my little john boat and the occasional buddys truck a few miles. I know a 350 would be plenty of power but i were to find a good deal on a 454 any reason i shouldn't go that rout?

 

[paratrooper307]

From a fit standpoint the swap isn't that difficult. You didn't say what year your blazer is, which makes a difference. 73+ trucks, some of which came with a 454, can fit one much easier, earlier trucks will run into clearance issues with the firewall. Most of the 454's additional length is in the front, which means it will bolt in pretty easily. The bellhousing is the same as a 350, but you will likely need a new flywheel/flexplate.

Exhaust manifolds are different, you will need new ones. You can generally use the same motor mounts, again assuming 73+.

TBI 454's are torquey, but aren't known for their power or towing capability stock. Depending on how much work you want to do with it, you can mod them some.

If your truck isn't FI (And since you said it's a 305 it most likely isn't) you'll need the harness, pump (probably fuel tank too), computer and other parts of the injection system if you want it to stay fuel injected. If not, you'll need a conversion manifold to go carb.

Big block means additional weight. You may need a stiffer spring or a zero-rate to offset it.

Good luck with what you decide!