I have a '73 GMC 3/4 ton truck that I use for hauling. The truck needs work, so I’m planning to fix it up. Also, the engine is worn out, so it will need to either be rebuilt or replaced. The previous owner pulled the 454 and put in a 396 (a “truck” 396 according to him, if that matters.) I’d like to stay with a bigger engine for the extra torque, so I’m considering one of the following:
Staying with the 396-- This is a fairly small engine so far as big blocks go, but it’s still a big engine and it gets acceptable mileage, even with the 4:10 gearing in the rear end (which I’d like to keep.) I’m friends with the previous owner’s family, and his son remembers that the truck ran well when this engine was fresh. Besides, I already have the core.
454-- This was the stock engine for the truck, but I don’t know if it’s worth the cost of a rebuildable engine. Besides, I’d like an engine that gets reasonable mileage and that is one thing that I have not heard about 454s. Emotionally, this is the least favorite option for me, but if there’s a good reason for my using this engine (namely tons of torque without a massive drop in mileage) I’d like to hear it.
Cadillac 472/500-- Sure, they were popular a while back, but I remember hearing great things about these engines. They’re light, powerful, and they supposedly get good gas mileage. Besides, it would be really cool to have a Caddy. On the downside, there isn’t that big of an aftermarket and the valve train needs help when running a taller cam. Also, I have no idea how much modification needs to be done to put one of these things into a chevy truck; does anyone here know?
The final plan is to have a truck for hauling, towing and for family camping trips, run at 1500-6000rpm. Thanks for any opinions.
This doesn’t quite follow your lead, but here it is. When I ordered my 1995 GMC 1500 (half-ton) pickup, I talked to a guy who worked at the truck plant in Fort Wayne, IN. He told me the most reliable engine available in that truck, including the big blocks, was the 5.7 liter engine (350 cu. in.) according to their warranty claims.
If you go to install a 454 make sure the engine is from latter production (post 89 if memory serves) The early ones were grenade monsters. Damn thing blew up right and left.
The thing to note with the Caddy engine is that it uses the BOP transmission pattern (Buick-Olds-Pontiac). So mating the engine to a tranny shouldn’t be any different then installing an Olds 307, or a 455 pontiac engine. You just need the correct transmission, or a dual pattern TH200-4R (or R4, I forget). The TH200-4R would have to be beefed up a little though for the added torque.
Now the thing with the motor mounts, you may need a kit, or fabricate your own. I would check out the Cadillac forums here for more info. They would be much more suited to answer your questions on Cadillac motor swapping.
Also, I remember looking into this option a few years ago, and there was a place in Texas that focused mainly on these engines. They had everything from mount kits, cams, manifolds, etc… I forget the name of the company, but there is hope for these engines out there. Plus, if all you’re doing is hauling, Edelbrock carrys cams and manifolds for these engines. That’s maybe all you need as these things are already torque monsters.
On the downside, there isn’t that big of an aftermarket and the valve train needs help when running a taller cam. Also, I have no idea how much modification needs to be done to put one of these things into a chevy truck; does anyone here know?