Unique 500+ Cubic Inch Engine Swap
 

The smog 350 in my '72 K20 is tired. It uses a lot of oil and is now burning water as well. Over the past two years I have been collecting parts for an engine swap. I want to go big - I don't care about fuel mileage for this truck, I just frame twisting, tire roasting low end torque with good mid range. The kind that makes it easy and fun to drive around town and can hook on a trailer and never look back.

Anyways, I have a couple of options. No matter what I do, I will either be keeping the 4 speed and swapping in 3.54 gears or leaving the 4.10's (with a heavier axle of course) and swapping in an NV4500 or the like.

Option number one that I have been leaning towards all along is a V6 GMC. I have all of the parts from a '68 GMC (Thanks Old_iron) so it would be a bolt in affair. I have a fresh 478M with a bad crank. Plan would be to offset grind the crank to fit BBC rods and custom pistons and cam to top it off. Should be in the 530 cubic inch range. Cost is going to be in the $4K range.

The other option that intrigues me is a 500 Cadillac. Can pickup a good runner for less than $500. It would take a flywheel and adapter plate from Cad Company and a simple cam swap to get it up to snuff. Cost would be in the $2500 range. If it ever had to be rebuilt, the crank would also get ground to BBC specs and would end up in the 530 cubic inch range...

Obviously the cost of the 500 is appealing, but I have always had a soft spot for big V6's as well.

What do you all say? Caddy is unique, but the V6 even more so...

Re: Unique 500+ Cubic Inch Engine Swap
 

If those were my only choices it would be caddy all the way. Stump pulling torque and probably better fuel mileage. The big V6s are absolute gas hogs, maybe 5-6 mpg. Caddy will get you possibly into the low teens

Re: Unique 500+ Cubic Inch Engine Swap
 

If you want big - why not a 572 BBC. Tons of torque, hp and an endless supply of high hp parts out there.

Just my 2 cents worth.

Re: Unique 500+ Cubic Inch Engine Swap
 

Big V-6. I'm a sucker for oddball engines.:metal:

Re: Unique 500+ Cubic Inch Engine Swap
 

I also love oddball engines such as this....

Re: Unique 500+ Cubic Inch Engine Swap
 

Caddy! You’ll love the low end torque. A cam and spring swap will wake it up significantly. Take a look at the Cadillac power message board. https://cadillacmagazine.com/forums/...k-cadillacs.3/
If it needs rebuilt find someone good to do the machine work, someone that knows them or is willing to do the research. Maybe even send it to Courtney at CadCo

Re: Unique 500+ Cubic Inch Engine Swap
 

If it's to get that grunt either engine would be good for providing, and nothing else but cool factor, I would go the big V6. And if you want to build it up, even better. The Caddy I would also really like in that truck. But you don't get that different sound only a V6, and even only a GMC V6 (especially a big truck one) makes moving it along. It's also a bygone American truck sound once quite familiar to all (over a certain age). Just keeping that alive is awesome. All these great running modern diesels out there, but you hear a Detroit and it just does something. Same thing here.

Re: Unique 500+ Cubic Inch Engine Swap
 

I wouldn't choose either of the choices. I have a .030 over 396 (402) in my truck. It has outstanding torque, power to do most anything.

Re: Unique 500+ Cubic Inch Engine Swap
 

V6 for the sheer joy of it. I have had experience with only one of those Caddy motors, but I was not impressed.

Re: Unique 500+ Cubic Inch Engine Swap
 

V6 for sure

Re: Unique 500+ Cubic Inch Engine Swap
 

There's a few members that choose a 500 Caddy.

Re: Unique 500+ Cubic Inch Engine Swap
 

Would love to, but that completely and utterly blows my budget.:waah:


Will probably end up with the V6 - the sound of an even firing order is truly mesmerizing. I think with a little head work and the right cam, 600 Ft Lbs of torque that has a curve similar to the top of my dinner table should be doable. :devil:

Re: Unique 500+ Cubic Inch Engine Swap
 

I used to think a 427 tall deck Chevy had torque - then I drive my brother's Highboy with a 472 Caddy....

Re: Unique 500+ Cubic Inch Engine Swap
 

You might be surprised at the cost of getting parts, machining, necessary mods required to make the engine reliable for the higher HP and torque.

I've got a 1967 Olds Cutlass. I ran a Olds 455 in it for 35 years. When it came time to get serious about HP and torque I found a complete ready to run, balanced, blueprinted, dyno'd 518 HP/585 lbs torque 468 BBC crate engine from Vortech Pro, complete with carb, MDS Pro Billet distributor and valve covers, for about half the price to get that kind of HP and reliability out of the Olds 455. It also came with a one year warranty with unlimited miles. That and worse case if something fails there are a bazillion parts available for the BBC. Finding good parts for the GM V6 might be a issue.

One more thing, a BBC in an Olds really pisses of the diehard Olds guys.

You might want to rethink the cost of a 'unique' killer motor.

468 BBC in a 1967 Cutlass.
https://live.staticflickr.com/4330/3...db684bcc_b.jpg

Re: Unique 500+ Cubic Inch Engine Swap
 

That V6 would be awesome. I hope you can go that route, I’d love to see it come together.

Re: Unique 500+ Cubic Inch Engine Swap
 

As long as you are looking for something unique with lots of torque why not use a GMC 702 V12....:)


Picture from this thread:

http://67-72chevytrucks.com/vboard/s...d.php?t=254111

LockDoc

Re: Unique 500+ Cubic Inch Engine Swap
 

I vote the 500 Caddy. I had a 66 Caddy with a 429 in it. It moved that 6600lbs with no complaints. I can just imagine what the extra grunt of the 500 would do.

Re: Unique 500+ Cubic Inch Engine Swap
 

What is it? I know, Late-War aircraft powerplant manufacturers were looking for ever bigger engines, but by the end of the period, were overtaken by jet engines, and piston engine development dead-ended in aviation.

Re: Unique 500+ Cubic Inch Engine Swap
 

Build the caddy and add a turbo.

Re: Unique 500+ Cubic Inch Engine Swap
 

I had a '78 Caddy with the 472. It was a dog, just as sluggish as my old '66 Bel Air with the 230 I6.

Re: Unique 500+ Cubic Inch Engine Swap
 

Was there ever a 1978 engine that wasn't a dog? :lol:

Here's a couple of torque monsters.
First one is a 30 cylinder Mopar and if that is too hard to accept.
The second one is GM's 12 cylinder version.

Here's the whole story.

http://www.theshermantank.com/sherma...to-production/

Re: Unique 500+ Cubic Inch Engine Swap
 

Your 78 caddy had a 425 not a 472 , The 500 is the engine to go with , the install would go easier if it was a 500 out of a eldorado then you would not have to find a oil pan for clearence issues . and if you took all the money that it would take to build that V6 to 530 hp and put it in a true 500 not 472 you would proberly be on the threshold of 800 hp. and also understand that these engines were built by cadillac so they recieved the best of the best, those blocks were the best and strongest Gm ever built in that generation.

Re: Unique 500+ Cubic Inch Engine Swap
 

Two V-12 Allisons put together. Fisher P-75.

Re: Unique 500+ Cubic Inch Engine Swap
 

You're right: my brain hiccough.

Still, I have no respect whatever for the supposedly awesome Caddy engines. It was disappointing in every way and not fundamentally different from the "superstar" 500.

Re: Unique 500+ Cubic Inch Engine Swap
 

From about 1973 and newer all the big cube engines were facing lower compression and retarded cams to meet emission requirements. I think the 454 got down to about 7.5 to 1 compression. Doesn't take much to wake them up. Jump them up to about 9-1 and add a mild cam and make those cubic inches come alive. Night and day difference