Unique 500+ Cubic Inch Engine Swap

[1972RedNeck]

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...

[kwmech]

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

[Rufas]

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.

[ApacheNick]

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

[yuccales]

Originally Posted by ApacheNick

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

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

['68OrangeSunshine]

Originally Posted by yuccales

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

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.

[1972RedNeck]

Originally Posted by Rufas

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

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


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.

[Rufas]

Originally Posted by 1972RedNeck

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

Vortech Pro

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.

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.

[clay68c10]

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

[special-K]

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.

[Ol Blue K20]

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.

[1972RedNeck]

Originally Posted by Ol Blue K20

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.

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

[palallin]

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

[Gigem]

V6 for sure

[cypressbog]

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

[57taskforce]

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

[LockDoc]

Originally Posted by 1972RedNeck

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...

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

[1972RedNeck]

Originally Posted by LockDoc

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

I actually had a line on a pair of 702's close by a couple years ago for $2500 a piece. If I was a better bodyman, it would be a fun project for sure.

Originally Posted by Steeveedee

I have a stock 400/400 with a 3.54 axle, and I'm happy with it.

I would be satisfied with that as well. My '66 Ford is built similar with a stout 410 (390 with 428 crank) mated to a 5 speed with 3.54 gears. Runs great, gets decent mileage, pulls well, etc. I am just looking for a little (well, maybe a lot) more...

[Dukk]

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.

[palallin]

Originally Posted by Dukk

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.

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.

[HO455]

Originally Posted by palallin

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.

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

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/

[Jrainman]

Originally Posted by palallin

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.

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.

[palallin]

Originally Posted by Jrainman

Your 78 caddy had a 425 not a 472 , .

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.

[kwmech]

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

[fourspeedwagon]

The 500 Cad would get the vote a hundred times over from me. I love oddball as much (probably more than) the next guy but that v6 was an odd duck that was put down for a reason.
Caddy bb is a marvel. Huge power/torque, moderately light (lighter than bbc) and as mentioned efficient enough to give decent mileage. 3 to 4 times what the v6 will give. The v6s I was around averaged 4 mpg. Very discouraging and it won't turn the rpm the 500 will.