: Chevy Big Block in a 1988

03-01-07, 02:50 PM
I have owned a 1988 Cadillac Brougham for about six months and I love the car except it is a SLUG. What was Cadillac thinking when they put the 140 horsepower Olds 307cid into this 4,180 pound car??

To resolve this issue, I have looked into putting a Chevy Big Block (454 cid) into it. I am going to build the 1974 engine to 1970 horsepower (from 270 hp to 350 hp). I know the Chevy will bolt up to the TH 200-4R tranny because the tranny has GM "Unicase" bolt pattern.

the only question mark is about the motor mounts. Will I have to weld in a "universal" GM motor mount adapter or is a "bolt-on" solution available?

I am REALLY psyched about this project and I already have the engine picked out. So, any information you can supply is much appreciated.


03-01-07, 09:05 PM
I would not put that 200-4R back in behind that 454 unless you want to rebuild it as often as you change your oil. This is one of GM's weakest transmissions. You would be much better off with a 700-R4 if you want to keep overdrive.

03-01-07, 09:20 PM
To put the BBC in, you will need to fab something up for the mounts. Closest thing I can think of to it in that chassis is the Big Block Cad. (encouraging from a dimensions standpoint) That had the TH400 behind it BTW.

03-01-07, 09:20 PM
Yeah, that's what I was thinking too, that 454 would rip through that 200R4 like an F-5 through Topeka.

Otherwise, I think it's a great idea, combining my love for the '80s Broughams with my love for the 454.

03-01-07, 09:56 PM
Although I have never done this swap it would not scare me one bit. As far as I'm aware a BB Chevy never came factory on this frame. My concerns would be the mounts and exhaust manifolds. Good luck and keep us posted on your progress, if yours works out I may follow suite. I'm buying a new car soon and will probably relegate my '91 as a sleeper project.

03-01-07, 11:01 PM
To install the BB all you need are the factory Cad mounts from a Brougham with the 305 or 350. The BB will bolt right to the SB mounts. The 200 will survive if you drive it like a Cadillac, not a drag racer. A later 700R4 will also work with the BB. You can likely keep the manifolds, but if you want headers, you can try mid-70s Chevelle BB headers. You will likely have to dent a couple of tubes to clear the steering.

The Ape Man
03-03-07, 08:59 AM
Jay is correct about the mounts. Get a 4L80E from a diesel vehicle or carry a bucket and a cell phone.

03-03-07, 01:15 PM
Yup, avoid 4L60's and 200 4R's. The 2004R can take more power than a 700R4/4L60 in reality because of the planetary gearset is 2.74:1 vs 3.06:1. The 3:06's are great for low end grunt, but they aren't strong enough for a 454.

Get some 1996-2001 L29 454 heads and a ZZ502 cam and you have an instant monster. I would recommend EFI, get a complete L29 or get the RV PCM and make it EFI with a L29 torquey intake. It makes a sweet combo. How do I know? I have a L29 454 in my 99 K2500 Suburban. It ROCKS.... And the 4L80E is a sweet tough transmission. I still want to toss the whole drivetrain in my 94 Fleetwood.....

Or get a THM400 and toss in a Gear Vendors OD, that can take a LOT of punishment.... Oh, and make sure you install a 9.5" rear end from a 93-96 Limo if you want to get punchy on the throttle. The puny 7.5" won't last long in that heavy ride if you are heavy on the gas.

Plenty of BB swaps into the Impala/Impala SS/Caprice have been done, so that much is pretty easy. Cadillac 500's are a great swap too. Check ImpalaSSforum.com for BB swaps in the 77-96 B/D Body. Remember, much of the frame is shared from the 73-77 A/G body too. BB's were available in those (maybe not Chevy, but Olds, Buick and Pontiac they were commonplace).

03-03-07, 07:48 PM
The 454 should have been in the eighties Broughams from the start. It's much more at home than the V6s, HT-4100 and other garbage that found its way underhood.

03-03-07, 07:59 PM
They probably would have got the same mileage if they put in a mild cam and kept the 2.56 gears....

The Ape Man
03-04-07, 08:22 AM
The Cadillac 368/425/472/500 ran circles around the competition when it came to moving large cars around and still getting good gas mileage. That's why it is so much fun to put one of these engines in a car that originally had a squirrel underhood. If you keep things like overdrive and don't go nuts on speed parts, the thing won't drain your wallet. The downside is less horsepower. 454s are a real blast and should swap right into a late 70s or early 80s Cadillac RWD. Maybe a later fuel injected setup could prove me wrong.

03-04-07, 10:05 AM
My 99 K2500 SPEFI 454 Burb, weighing in at 5600 empty, 3.73's, 245 75 16's (overall same tire/gear ratio at 235 70 15's and 3.42's), 4L80E, a towing shift pattern (like TCC won't lock up until 68 mph...GRRR), and with 6 people in it, guessing with fuel and junk, probably 6500's. And I get a best of 13.2 highway so far with stock PCM program (I have tuned now, but not seeing any better yet). I see more like 10-11 city.

So yes, a well designed tuned Cad 500 would probably be a better mpg choice.... The 454 is powerful, but not good on gas. My 454 has a cam in the 206/211 duration range, around .480 lift. Small for a 454. They say the ZZ502 cam REALLY wakes up the 454.

(ZZ502 cam specs are here: http://www.gmperformanceparts.com/EngineShowcase/tech_specs.jsp?engId=ZZ502502HO&engine=ZZ%20502/502&sku=12496963&engCat=bb)

03-04-07, 11:19 AM
Call me a rookie, but I don't get how a smaller 7.4L would be worse on gas than an 8.2L in the same car. Plus, isn't the number of aftermarket performance parts a big advantage to the Chevy 454 versus the Cadillac 500?

03-04-07, 01:05 PM
Call me a rookie, but I don't get how a smaller 7.4L would be worse on gas than an 8.2L in the same car. Plus, isn't the number of aftermarket performance parts a big advantage to the Chevy 454 versus the Cadillac 500?
I had a '74 Fleetwood with a 472 and it was a pig on gas. I'd go for the BB Chevy!. And yes, there is a huge aftermarket for the BB Chevy and a very small and expensive one for the Caddy. Only way I'd do a BB Caddy is if it was late 60's or very early 70's motor and I would keep it stock.

The Ape Man
03-04-07, 01:12 PM
1 pig doth not make all Cadillac powerplants pigs. I had a '71 472 which was a pig and a dog. Had a bunch of 75 and 76 500 cars/engines which were not.
Engine size isn't the whole story. Camshaft, port design, valve size and location are totally different between a big Cad and big Chebby.

03-04-07, 01:42 PM
What he said!

My 455 Pontiac in my 80 T/A was commonplace to get 16 mpg highway with no OD, 3.08 gears and 28 in tall tires. Carby and all. I tossed in a Cam Dynamics 284H (228/228@0.050, 0.480 lift on a 112 lobe center with a 112 lobe separation), 750 cfm Edelbrock AFB and Performer intake. My mpg only dropped to mid to high 15's highway. That is at 75 mph, running nearly 3000 rpm. I only wish my 454 would get that "good"...

The 76 Olds 98 with a 455 and mild cam, and 2.73 gears was EPA rated for 12 city and 18 highway. Not too bad. The EPA rating on my 76 Delta with 350 was 13/17 and that was pretty accurate.

03-04-07, 09:28 PM
I had a '71 472 which was a pig and a dog. Had a bunch of 75 and 76 500 cars/engines which were not.

How could that be? The '71 was the high compression 472..made for a hell of a lot more power/torque?

03-04-07, 10:02 PM
More torque yes, not more hp. Typically peak mpg is at or very close to peak torque. The BBC usually shoots for higher hp peak because the lower end is capable of it. So the torque peak moves higher too, so running similar gears as the BBCad the engine is running less than efficient.

So yes, less mpg with the smaller BB.... BBChevys have larger ports too, so that makes for less port velocity, also hurting throttle response and mpg when at lower rpms.

The Ape Man
03-05-07, 09:58 AM
How could that be? The '71 was the high compression 472..made for a hell of a lot more power/torque?

Generous motors lowered compression after 1970. The '71 472 was low compression. The hell of a lot more power thing isn't what it looks like as ratings cannot be directly compared. Older ratings are "gross" and later ratings "net". There were a number of engines which used all the same part numbers as the previous year but were rated at 30-45% less under the "net" rating.
I'd post a nice link but it's against board policy. Just Google "1971 GM compression". Drop the quotes of course. How Stuff Works has some good info.

07-03-07, 09:54 AM
Chevy 454 is now at home in the 1988 Brougham with a TH400 tranny right behind it! The only thing keeping me from driving it is a special order combinational universal joint and will have that in two days.

The Chevy 454 and TH400 look just right in the Big Caddy. No special brackets were needed! I just used aftermarket motor mounts designed for a 1970 Chevy Monte Carlo with a 454 cid...same goes for the TH400 tranny. I was pleasantly surprised by just how easy it was to get everything to fit.

Patience is the key! The old style GM B-Bodies are almost exactly like the GM D-Bodies, except for 10" longer wheel base. Also, when in doubt, try the aftermarket part for a 1970 - 1972 Chevy Monte Carlo with a 454 cid. Even the radiator fit!

Also, forget the electronic control. While you are making it a drag racer, MAKE IT LIKE THE 1970 Chevy Monte Carlo with a 454 cid. Keep it simple!

VERY IMPORTANT...pull out the "Check Engine" light bulb and replace it with "Engine Missing" light bulb.


07-03-07, 09:58 AM
Engine now has 468 cid and tranny is like like that of a 1973 Vet!

07-03-07, 10:01 AM
Chevy 454 is now 468 cid (with 10:1 compresion) and TH400 is like that of a 1973 Vet!

Jonas McFeely
07-03-07, 10:13 AM
I demand PICS!

07-03-07, 11:24 AM
Considering the 73-77 A/G chassis (MontoCarlo/Chevelle/Malibu/ElCamino)was designed around the BBC (only 73-74 got them), and our chassis is based on those cars, it should be a bolt in. And the 64-72 isn't far off at all....

Pics! Lets see a classic burnout! I'll show pics of my LT1 burnout (aftermath, hard to do when you are driving!) if you show yours!

Dropping in a BBC into a D Body should be easy as Pi!

The Ape Man
07-03-07, 05:46 PM
Did you do anything special with the transmission and rear axle? That open rear will really limit your 1/4 mile times while you smoke the tire. Congratulations on getting something done. I can't seem to finish anything these days.

07-03-07, 05:49 PM
Maybe just install a 28x33x15 slick on the right rear.....

07-04-07, 12:36 AM
The tranny has been built like an old school dragster--so says the builder. He put in a shift kit, bored the valve body (a bit), put in Kevlar bands. The new torque converter is the same as those used in the Vet's with the TH400 tranny (not sure of the year). The stall speed is 2500 rpm? I'm guessing.

The drive shaft is out of 2WD GMC K3500 with a 454 cid. Instead of shortening my driveshaft, I found this one was exactly the right length (59.5 inches). It's a good strong shaft too. It has been a little difficult to find the right conversion U-joint though. The front one wasn't that hard, but the rear one had to be special ordered and cost $60. (Must be made of titainium!)

The rear end is a Dana limted slip at 2.93:1. This is the factory configuration. I wanted to see how it is going to react before I go changing the gear ratio. There are ratio kits available from 2.50 to 3.73:1. I also toyed with the idea of putting an "overdrive" kit into it. TCI make a Kewl one for about $1000.

I will keep you all posted. BTW, TCI sells a built TH2004R that is rated at 750 horsepower. It is about $1,200.


07-04-07, 12:54 AM
Now all I have to do is figure out what to do with all the extra vacuum lines and anti-pollution sensors. BTW, the intake is an old school (bi-plane?) high-rise. The carb is the Quadrajunk 4MV that came out of K3500 truck.

The engine also came out of the same truck that had oval-port heads. Cam is a medium lift. I'm surprised how smooth it runs with this cam and 10:1 compression.

Got lucky...after putting on a Summit Racing (low-profile) air cleaner and the hood, I have about 1" between the air cleaner and hood. I had to remove the sound deadener, though. That's OK, I WANT to hear my new engine!


07-04-07, 03:43 AM
A friend has devised an "on-the-move" refueling system. It is inspired by that which is used to refuel Air Force One in flight.

The buddy knows I am getting tired of the "Pass everything, but a gas station" joke and put his mind to it. Seriously, I would think that I will get 12 to 16 miles to a gallon. With the Caddy's 25 gallon tank, that's about 350 mile cruising range.

Good thing I only live 3 miles from work!


07-04-07, 08:53 AM
Great work! Show some pictures or videos :thumbsup:

07-04-07, 10:13 AM
I will definately post some pictures once the STUPID universal joint comes in! That is the only thing keeping it from growling to life. Once I have it on the road, I will provide results including pictures.

Fair enough?

07-04-07, 05:18 PM
I will definately post some pictures once the STUPID universal joint comes in! That is the only thing keeping it from growling to life. Once I have it on the road, I will provide results including pictures.

Fair enough?
pi-No, it aint fair enough. Why cant you just post some pics of the motor in the car and of the swap itself. Nobody wants to see the u joint anyway. We just wanna see it, pleeeeeeeeeez!. :thumbsup:

07-04-07, 07:38 PM
Post some pics when it's done.

07-05-07, 01:01 AM
What is up with the u-joint? What is the problem?

07-05-07, 05:57 AM
:bighead: As I said in an earlier post, my drive shaft is about 2" to long. So, instead of having it shortened, I deciced to use a shorter drive shaft that I found in a bone yard. The shaft is out of an early 70's K3500 pick-up and is exactly the right length (59.5").

Eventhough the shaft is much stouter and will be stronger to support 450 horsepower, the cap bearings that fit this shaft are very hard to find. So, when I went into Summit Racing Equipment with shaft over my shoulder, they just laughed at me. (Not sure if laughter was from the U-Joint request or the fact I came in with a 30 year old truck drive shaft slung over my shoulder.)

Well, after two trips back and forth to Summit Racing, they finally said that they could not help me. So, I asked the gentleman if I could look at his book myself. Well, after 10 minutes of measuring (I took my own calipers with me.) and searching the book, I finally found the right conversion U-Joint. Unfortunately, it was on back-order for two-weeks.

So, with the right part number in mind, I did some searching on the internet for it or a cross-reference joint. I found it (only three in stock in the country) at Six-States Distributing web-site. I called them and verified availability and ordered it with my credit-card. Shipped Fed-Ex 2nd Day. I'll have it today!

That's the story of the elusive u-joint. :bighead:


07-05-07, 01:04 PM
Ahh, cool. there is a place here in Elkhorn, WI, Parts Place, that has an amazing amount of stock of parts, even odd ones. I wouldn't hesitate to call them on odd stuff. They guys are father and brothers that own the place, it is the old parts store that has more stuff stuffed into every corner than you can imagine.

Glad you found it. Now, to find a shaft that is lighter aluminum, like on the newer full size trucks. I am going to work on that, with the 3.42's in my car, the shaft gets pretty buzzy at higher rpms, and scary at 130+..... (don't ask why I know that....)

07-08-07, 10:16 AM
Thanks for all the help in this project; I really needed the support through this project as some of the retrofit was quite discouraging. Finally though, everything is coming together and I just have a few more (minor) issues to iron out.

BUT, the ol' 1988 Brougham is moving under its own power and has a new lease on life! Even before I have the thing timed correctly, I am amazed by the extra power I have. I finished topping off the tranny fluid (Dexron 3) to the TH400 and dropped it into gear. The tranny instantly coupled and the car lurched forward! I put on the gas (slightly) and the car spun some dirt in the driveway.

The old driveline never spun up anything but my anger! I drove it up and down the driveway to test throttle response and I can tell right now that my timing needs some work. Also, I only have (Precision Pypes) front pipes on right now and I wanted to avoid any heavy acceleration until I get the entire exhaust system put on. I assume that this will also affect throttle response, as well.

I need to research what static and dynamic ignition timing I need as the engine is not stock anymore. I also think that the vacuum advance dashpot is defective and isn't advancing the timing like it should. Maybe I just need a new one or a another one with different advancement characteristics.

Does anyone have any idea where I can find such information or where I can send e-mail for expert advice?

Again, vital engine spec's are:
1.) Chevy 454 bored to 468 cid
2.) Compression ratio is 10:1
3.) Medium lift camshaft
4.) Oval port heads
5.) High energy ignition, but NOT computer controlled.
6.) Quadrajet 750 to 850 cfm carburetor (not sure of the flow)
7.) Edelbrock high-rise (bi-plane) intake manifold
8.) Stock exhaust manifolds (not headers) into dual (2.5 inch diameter) pipes

Thanks agian for the support,

07-08-07, 06:06 PM
So, now, time to modify it for more power eh?

A set of stock L29 heads off the 96-02 454s. You can get a LS1 PCM that will control the 454, so you can use the high torque L29 intake and EFI and even do coil on plug ignition, as the L21 454 (the very close kin to the L29 454, just found in RV's and medium duty trucks). With your a ZZ502 cam and these heads you can probably see 370-400 rwhp and 500 lb/ft torque with 87 octane pump gas and fantastic throttle response. Probably more...

Game? More is sooooo addicting....

07-08-07, 06:15 PM

Ask for Old Bogie. One old veteran of the first days of hotrodding.


07-09-07, 04:47 PM
so where's the pics?

07-22-07, 10:41 PM
Is it me or was this whole thread BS?

07-23-07, 07:18 AM
Even cell phone pictures work....