: Need info for Chevy engine swap into '70 Coupe



White Whale
11-01-04, 02:25 PM
Hello all...
Does anyone have a source for FRONT engine mounts to allow bolting a Chevy Big or Small block in a 1970 Coupe DeVille?
After a little looking, I have already found a bellhousing adaptor.
I know, keep the 472, and there is a strong possibility that I will.
Also, I know that 4,500+ pounds is a lot for a small block, but my Suburban weighed 5,200 or so and the 350 did just fine.
No off the line power, but I stopped racing a while back.
For some reaon I like to do this kind of thing.
I can engineer and fab the mounts myself, but it would be a LOT easier to just get some prefabs.
Has anyone else done this? I assume you have and I didn't spend the time to scan the site for the thread.
Thanks,
Mike

lux hauler
11-01-04, 03:22 PM
Hello all...
Does anyone have a source for FRONT engine mounts to allow bolting a Chevy Big or Small block in a 1970 Coupe DeVille?
After a little looking, I have already found a bellhousing adaptor.
I know, keep the 472, and there is a strong possibility that I will.
Also, I know that 4,500+ pounds is a lot for a small block, but my Suburban weighed 5,200 or so and the 350 did just fine.
No off the line power, but I stopped racing a while back.
For some reaon I like to do this kind of thing.
I can engineer and fab the mounts myself, but it would be a LOT easier to just get some prefabs.
Has anyone else done this? I assume you have and I didn't spend the time to scan the site for the thread.
Thanks,
Mike
I have never heard of anyone putting a SBC into an early 70's Cad.....most would rather have the torque of a big block. You'll probably have to fab the mounts.
You mention your suburban.....the big difference between the two is going to be the rear gears. The Cads gears are designed to work with a high torque engine. I'm sure your 'burban had no higher than 3.07's...probably closer to 3.73's....the Caddys were higher than that......probably in the 2.70 range.
A sbc will move it but I don't think you'll be to happy with the power or the amount of fuel you're gunna burn to get (and keep) that tank moving.
Cadillac put big engines in those big cars for good reasons.

White Whale
11-01-04, 03:57 PM
lux,
True on the gear ratio point, but with the OD, it comes out to a 2.39 final drive ratio in the Suburban, (3.42 x .70) and I got 16.5 from it.
I was thinking of a 383 small block, but I also have a 454 in the build stage.
Just looking for a possible "do it different" project.
If the small block didn't satisfy, stuff the 454 in.
Another option would be a big diesel.
It will all depend on what I can find around here as far as affordable Caddy mills.
Given what you said, wouldn't the 368 have the same problem, lack of lowend power?
I suppose that with the 10:1 CR of the stock 472 I could run water injection and use the high squeeze to get some decent mileage out of it.
Thanks for the help and input.
Mike

lux hauler
11-01-04, 05:36 PM
The od doesn't come into play when the engine is under load though. Again, I don't think you'll be happy with a big, heavy car with a sbc whether the gears are high or low.
The 368 still had decent low end torque......that and the cars in '80 were lighter than they were in '70.
I'm all for doing things different....different is cool, but how different is a car with a Chevy engine? Different is a twenty foot long, 4600+ pound sled that'll wipe the smile off of the faces of some of the "proudest" muscle car owners and doing it with an engine that most would consider a "boat anchor". :thumbsup:
Keep the 472.....less work, not much more money (when you figure your time fabbing and other costs of fitting the chevy in) and gobs of torque that only a long stroke engine can give. :yup:

White Whale
11-01-04, 05:59 PM
lux.
Keep it up and you will talk me into it ! !
How about the Edelbrock intake I keep reading about?
Is it good for these engines from a mileage standpoint?
Right now I have a '65 Chevy half ton that I swapped a '77 Malibu rear end into.
It has a '70 Vette 350, stock cast intake and an Edelbrock 1404.
All that said, I get a little over 20 mpg out of it after tweaking the 1404.
I would hope that the Edelbrock Caddy intake and carb would be better on fuel than the stock 100 or so pounds of intake and Q-Jet.
Adapting an early nineties GM TBI is also an option, but I would have to get a special or program-able chip to do Hydrogen and water mods.
Running water on top of that 10:1 compression should help a lot.
I guess one of the older style Holley FI units would be better for that.
Too many projects, eh?
Great site, and I like that image you have up.
Mike

Night Wolf
11-01-04, 08:59 PM
honestly I would never do that swap at all...

the 350 would be a decent engine in the 1977-1992 DeVille/Brougham (as it was in the 90's) much better then the HT4100, and 307.... not as cool as the 425 though...

... you would be stressing the 350 often just to do what the 472 wouldn't even think twice about.... plus, IMO it is grat to have a Cadillac V8 under the hood.... especially when you are driving a Cadillac car....

if gas millage is your thing, IIRC it is MTS that offers a cam that'll get you an honest 20mpg form the stock big block... although it'll bring the torque curve even lower then stock.... if you are doing a super build on an enigne... 500hp+ 600ft-lbs tq.+ etc... you'll find it is cheaper to go with the BB Cad then a SBC..... even a simple Edelbrock intake manifold, rebuilt carb (keep the Q-Jet) a performance cam, some headers, and a nice free flowing true dual exhuast system, and you'll really bring the 472 to life... you have no emmisions, so that is a plus, and you have 10:1 CR (vs. my 8.2:1 ont he '79) then just swap in a HEI ignition system, and you will have an over all much better enigne... IMO.... plus these BB Cad's are bullet proof....

also keep in mind, the '70 DeVille weighs about 5,200lbs... throw in 25 gallons of gas, 2 people, various stuff in the truck etc... and it really isn't all that hard to tip the scales at over 6,000lbs.... that is more then the average SUV today.... so don't expect a race car out of even a modified 472, but it'll defitily haul when you want it to....

... perhaps that is the biggest thing I like about my '79.... big block Cadillac in a car that weighs 4,500lbs... while still having more luxury features and comfort then any Honda could ever think of...

Edahall
11-02-04, 12:34 AM
How about installing a 6.2 or 6.5 GM turbo diesel? I've got a non-aspirated 6.2 diesel in my Suburban and it gets 23 mpg average on the highway doing 75 mph. Acceleration is not that bad either, 0-60 just under 10 seconds. A 300 hp 6.5 turbo diesel engine in a car like yours would be a really nice engine swap and would have more power and torque than the 472.

lux hauler
11-02-04, 09:28 AM
Honestly....if it's good fuel mileage you're looking for, you need a different car.
A smaller engine will get decent mileage and performance in a smaller car. In a big, heavy car, a smaller engine is going to have to work too hard to get anything decent. A bigger engine will handle the weight of the car but is also going to use more fuel.
If you figure the cost of all the mods and parts you'll have to buy to get "better gas mileage" against the amount of money you'll save in fuel costs after the mods, I think you'll see that it'll probably be cheaper to sell what you have and get a different car.....just my $.02

White Whale
11-02-04, 10:51 AM
Wow,
I knew I would be whacking a nest with this one, but I am getting the info I need to make an informed decision.
Due to my height and a resultant problem with my knee, I HAVE to get a bigger car in order to stretch my leg out when I drive.
I make enough so the price of fuel is not a big concern, I just want to make any vehicle I drive as efficient as possible.
This car will be used for long hauling back and forth from Phoenix to Central Texas, and for my daily driver.
I fully understand the ramifications of putting a smaller engine in a barge, i.e. the resultant strain on the engine, using more fuel in the pursuit of saving fuel, increased loading that a big engine wouldn't even notice, etc...
I grew up on big block Chevy powered beasts, and have had a couple Caddies in the past.
A 500 is a joy to have, as my '68 CDVC had one in it.
Just looking at options.
This site is great, and you guys seem to be willing to help any way you can. :thumbsup:
Thanks again, and more to come.
Mike

White Whale
11-02-04, 11:44 AM
Edahall,
Good idea on the diesel.
try www.greasel.com
That will be my next round of questions, about swapping in a diesel.
But more on that later.
thanks,
Mike

Fred Fachman
11-02-04, 11:46 AM
I thumb past a lot of the threads here, but this one I have to vote on. The 472/500 is the only way to go. Under no circumstances should a Cadillac of that era have any other powerplant. You will be disappointed with anything less and if you do insist on putting in ANY other mill, I will be the first to tell you " I told you so". Thats my vote. After all it is election day.

lux hauler
11-02-04, 11:59 AM
This car will be used for long hauling back and forth from Phoenix to Central Texas, and for my daily driver.
I've never been to that part of the country but I'm assuming that it is fairly flat.....not alot of steep-ish hills....(?) That being said, an efficiently built Caddy 425 out of a '77-'79 Cad might do you ok.....? it'll also bolt right in. Then again, if you're gunna build the 425 efficiently, you might as well build the 472. :D
BTW.....if you decide not to do anything with those "950" heads......I might be interested in them. :yup:

White Whale
11-02-04, 02:22 PM
lux,
I was waiting for you to mention the heads ! :coolgleam
If I don't use them, we'll talk.
It's a good thing I can take a ribbing, you guys are tough. (i.e. Fred "The Hitman" Fachman) :D
My background doing street rods and odd mods got me into trouble here. :hide:
Though generally I am a purist about correct engines in the correct cars, I just wanted some ideas. I got them.
There is nothing like a big old Enginesaurus between the framerails, on that there is NO argument.
If this car didn't have an engine, a 500 would be the ticket, after all, what's an extra 28 inches going to matter on MPG?
BUT...it does have a wounded low milage 472 in it, so we'll see.
When I finally get down to it I will be sure to update all ya'll on what's being done.
Thanks again,
Mike

Edahall
11-02-04, 03:23 PM
Here's a page that shows a 6.5 turbo diesel swap into a Buick

Click Here!!! (http://www.thedieselpage.com/readers/timo.htm)

barge master
11-04-04, 08:10 PM
The stock engine is also a front sump pan. I don't think a rear sump of any sort would go in that chassis. That could turn into more hassle than it's worth right there.