: 79 coupe deville help

05-09-05, 09:41 PM
I recently purchased 79 coupe deville I was wonder if you all could give some basic info such as avg. mpg,easy hp upgrades, top speed, good places on the net to get parts, and any other benifical info that you can provide me.
thanks Zak


DopeStar 156
05-10-05, 12:07 AM
85 MPH THat's what your speedo says, that's all it'll do with that governor in there.

05-10-05, 01:58 AM
85 MPH THat's what your speedo says, that's all it'll do with that governor in there.

... Not sure if you're trying to be funny, but there's no governor and I had my 78 Fleetwood north of 100 a few times. I averaged 112 I think over 10 miles once. It seemed fast at the time but then I got my ETC to 153... anyway,

You'll probably get low double digit MPG.

Your engine's a 425CI V8 backed by a 3spd TH400 transmission. Check the 500/472/425/368 engine forum on here for more info there.

DopeStar 156
05-10-05, 02:52 AM
... Not sure if you're trying to be funny, but there's no governor and I had my 78 Fleetwood north of 100 a few times.
Whoops! It's a '79! My bad. Dave's right, no governor. It'll fly. I'm stuck in late 80's Brougham mentality.

05-10-05, 10:28 AM
so what about like easy hp upgrades? what would be the first things you would do?biggest bang 4 the buck?

05-10-05, 05:57 PM
Biggest bang for the buck would be to either remove or empty the cat. Look in the 500 forum and do a search for more info on it and other things you can do.

Night Wolf
05-11-05, 08:25 PM
yeah... no governor... and 85mph on these cars are a joke... since it comes and goes so fast (it'll burry the speedo in 2nd :) ) on a long strech of highway here, my '79 all stock, I got her up to 110 according the the GPS... then I had to slow down for a turn.... but the tires are also bald... and not balanced... so I am not doing that again (until I get new tires)

Anyway, with a tuned carb in good shape, if you are easy on the gas, you should be able to get about 14mpg... up to 18-20 on the highway if you set the cruise around 70

easy hp upgrades:

dump the cat... get rid of it... I drained the beads from mine, only so it looks like its still there (kinda pointless)

get a 14" open element air filter

rebuild the carb

get a 472/500 intake manifold, remove the center section (do a search for it) and install that

put a high-flow muffler on

Then if you can, dump the 2.28 gears... unless your car has the factory towing package... getting a 2.78 Posi from a limo would be the best... but the 2.28 gears kill the performance of this car... atleast from a stop, once she is moving it accelerates rather good :)

BTW Dave... you got the '95 ETC to 153mph? no speed limiter? or are you lucky enough to have a Z rated car?

There was always something I loved about those cars... 1995 is actually one of my favorite years... I used to hate that dash, but now I like it alot...

DopeStar 156
05-12-05, 12:45 AM
Can you dump the cat and still pass inspection?! I've been looking for cheap ways to boost HP.

Night Wolf
05-12-05, 10:21 PM
Can you dump the cat and still pass inspection?! I've been looking for cheap ways to boost HP.

could *I*?


my car is over 25 years old... exempt from emmissions :)

Although now I hear in NY it is only 1996+ (OBDII) so I don't know.

What I do know is, in FL, there is no emmissions at all... hell there isn't even inspections :) which means I want to dump the cat on my Oldsmobile (since it'll be my only car) and it should be easy enough since we had to clamp the exhaust right before, and after the cat since it blew off :)

05-13-05, 02:45 PM
get a 14" open element air filter

BTW Dave... you got the '95 ETC to 153mph? no speed limiter? or are you lucky enough to have a Z rated car?

I'm not sure the 14" open element will do any good. The stock air cleaner should supply all the air the engine needs, and it supplies cold air rather than the hot air an open element will intake.

Yep, the ETC is Z rated. The 153mph was done with retarded timing from a stuck EGR valve and on 86 octane gas at about 5000' above sea level, so I think it can go even faster :D I blew right by a crown vic when I was doing it too, couldn't see if it was a cop so I just killed the lights and kept it to the floor. :halo:

05-13-05, 10:37 PM
thats good b/c I am in Fl anywayz

Night Wolf
05-13-05, 11:26 PM
killed the lights? at night? lol

How hard was it to find the Z rated car? I heard it was only a $334 option or so when new, but hardly any of them have it.

I know on my car the 14" Edelbrock helped power a good amount.... the facotry air cleaner is rather restrictive, and it mostly concentrated the air on 1 part of the filter, I got tired of having to rotate the filter almost weekly on it...

about the cooler air... it does get it from behind the headlight, but the open element has 360* of space, not to mention the huge blast of air from the mechanical fan... when the car is moving say, 50mph, bewteern the car moving alone, and the huge fan, the air under hood simply dose not have enough time to heat up enough to make that much of a difference by the time it gets to the air filter.

It also cleaned up the engine, no more ait duct hose and that metal hose to bring in hot air (which never worked on my car) and stuff... plus it looks cool, and sounds really good when the secondaries open... it was like $40, but also came with a new air filter, it was worth it to me atleast...

nothing like some ricer revving up his POS 4 banger with a fart can, then me revving the 425 kinda easy, and it is mellow, and the kid in the ricer kinda laughs, then I put it to the floor and it growls, then the look goes from laughing to scared.....

good times :)

Night Wolf
05-13-05, 11:27 PM
also when running the engine wide open, I thought EGR wasn't being used... so in your case the EGR didn't have much to do with it did it?

Night Wolf
05-13-05, 11:30 PM
BTW you live in NM, but bought the car in CT?

all without stopping by in NY to say Hi?....thats it :)

Anyway, did you fly out there? What is the store with the Eldo anyway? I just remember you asking if anyone wants car faxes, and that you got it becuase the '78? was using too much gas... then you killed it?

lets hear about it... hell, drop me a line on AIM - InoventionsEast if ya don't mind :)

05-15-05, 06:57 PM
killed the lights? at night? lol

How hard was it to find the Z rated car? I heard it was only a $334 option or so when new, but hardly any of them have it.

I killed the lights except the fog lights cause those are some very recognisible taillights the ETC has. I thought all ETCs got Z rates in 95 but I'm not sure.

also when running the engine wide open, I thought EGR wasn't being used... so in your case the EGR didn't have much to do with it did it?

I don't know much about these newfangled computerized engines but I heard that when the EGR is malfunctioning the PCM will step to a lower timing curve.

BTW you live in NM, but bought the car in CT?

all without stopping by in NY to say Hi?....thats it :)

Anyway, did you fly out there? What is the store with the Eldo anyway? I just remember you asking if anyone wants car faxes, and that you got it becuase the '78? was using too much gas... then you killed it?

lets hear about it... hell, drop me a line on AIM - InoventionsEast if ya don't mind :)

I bought it in CT, I drove through a part of NY (got a blowout in Middleton, less than a half mile from the Caddy dealer there fortunately.) Late last year the 78 developed a serious bottom end knock so I took it off the road. My grandmother didn't have a car so I was letting her use the 75 Deville (which I now have since she got a Plymouth Breeze :helpless: .) So I was looking at 94-96 Fleetwoods, LT1 Caprices, and P71 Crown Vics because I like the big sedans, but I ran across this beautiful ETC at a good price. It's crimson pearl (my favorite color, ) and the best year for ETCs (300hp, OBDI,) so it was too good to pass up at $3800. It was in CT so I flew out and drove it home (some advice for anyone reading... if you buy a car more than a couple hundred miles away have it shipped.)

I'd have hit you up on AIM but I don't use it.

Night Wolf
05-15-05, 09:59 PM
My gosh...

I didn't think of the fog lights... none of my cars have them.... but that was good thinking :)

the computer can do things with the EGR, but when wide open, the EGR is shut down

You got a blow out in Middletown? sheesh that is only like 30 minutes from here! let me guess, you were on 84? must have been to be coming form CT, as it runs right thru there..... did you take 84 to 87 then go South? if so you passed RIGHT by me... otherwise you kept heading West?

I never thought about 1995 as the 300hp/OBDI thing... does OBDI/II really make a difference on the N*? it isn't like there is much performance parts to begin with....

If all 1995 ETC's are in fact Z rated, that that is *THE* car I would like to get! :)

I would love to fly across country to drive a new car back, I think that is pretty cool!... my '93 DeVille was bought in FL and driven up (not by me.... family member) no problems at all, can't beat a FL car :)

What did you do with the '78? I thought i remember you said you got rid of it? Although I guess any nice 500 build up will be done to the '75? (I love the '75/'76 Coupe DeVilles)

In either case, the '95 ETC is a great car..... I have a really bad manual transmission bug (thanks to my friend who taught me to drive on his '94 Jetta, then lets me drive his '01 Jetta 1.8T) and if I want a simple daily driver, 5spd car, I would get a '96-'98 Pontiac Grand Am GT with the 2.4L 4banger and 5spd. If I had a little more money to spend, I would definitly get a '95 ETC. I would want black, then silver, then Polo Green. As of late my want for a truck has gone way down, so I guess that is good.

Then the question arrives.... when I can afford a "new" car (such as the '95 ETC) do I really want to get that? or for the money, I can build up a really nice 500 to put in my '79 and actually do the origanal intentions that I bought the car for.... not to mention I could get my '93 DeVille repainted too....

decsions decsions.....

I used to hate the gauge cluster on the '95, and really liked the '96, but that has since kinda changed.... reasons why I like the '95 dash.... the climate control is on the right side, only the driver can access it (much like my '93 DeVille) and says both inside and outside temp. The fuel data center is on the left side, seperate from everything else, says instant or ave. mileage as well as range and stuff (2 displays, that is cool) and the information buttons are all on the left side (vs. middle for '96+) this creates a very cool driver-orientated setting (much like my car) and leaves the center stack empty and clean looking excpt for the radio (which is very easy to change... not so on the '96+) I like the '96 gauges in that they are bigger and have the red and such, but still, they '95 are nice...... only thing is I don't care for the shifter, I would try to get a '98+ Seville STS shifter (the all wood ones) to fit on there :)

I'll stop my rambling now.... but that is a sweet car!.... too bad we live far away, I think a meet or something would be cool.... gonna be in FL at all later this year? :)

06-10-05, 09:08 AM
You know I never saw the above reply... and since I have absolutely nothing to do I'm going to reply to it even though it's like a month later.

Rick, that's interesting that I drove by pretty close to you, I took 84 to Scranton I think. Should've figured out how to ask you for advice on a tire store instead of driving about 450 miles at 65-75mph on a donut tire rated for 50 miles and 55mph.

The OBDI is only good for my peace of mind right now, so if in the future I do something radical like install a Getrag 284 5 speed manual or a turbo or something, then it won't be as hard to get the computer to play nice with it.

Flying in to pick up a car and then driving it cross country is a hell of an experiance. Especially for someone our age. I'd say it's a bad idea for anyone under 18 though.

Things like not getting a temp tag and getting pulled over, being stranded 2000+ miles from home in a -10* blizzard and not being able to get a hotel, getting 2 blowouts, one where you slide off the road into a shallow ditch JUST when your cell phone runs out of battery power, waiting for a cop to show up to call AAA and hoping he overlooks your plate being from a differant car, having to walk through 3 miles of snow to get to the tire shop that AAA towed you to, then hitting another snowstorm.... All that can really put a damper on an otherwise fun trip. I should write that whole story down and publish it in Readers Digest or something.

Anyway the 78 is still in my yard, the parents were going to have it towed but haven't yet. Someone on here wants parts for his Deville but I'm having a hard time doing it since it was my first real car.

This is my evil plan for the 75: Monte Carlo BBC headers adapted to 500 flanges and dual exhaust, modified stock intake manifold, 76cc 68-73 heads for 12.5:1 compression, and a cam with about .600" lift like the MT20 from MTS. Although I'll probably use Cad Company parts since I can just drive down and pick them up. I'll also run a propane carburetion system because propane has a 105 octane rating which should support 12.5:1 and propane is cheaper than regular 86 octane unleaded. Should be good for 475hp or so with maybe 550ft.lbs. Then forged pistons and rods and a really big hit of nitrous.

I really have a manual transmission bug too. So much so that I've seriously considered swapping a Getrag 284 5 speed into the ETC. The problem is that it's only rated for 250 ft.lbs. and I want to nitrous the ETC which would destroy that transmission. I've even been pondering a RWD conversion. The ETC really would be the perfect car for me if it had a manual. I'd like the 75 to have a manual, but 550ft.lbs. means it would cost a LOT for a trans that wouldn't grenade.

When you can afford a newer car... I'd probably advise you to not buy a newer one since you have the 93 I'd just repaint that and build a nice 500 for the 79.

If you do decide to go with an ETC 95 is a great year. The only other year up there with 95 is the 02 collector series. I really don't like the 96 shifter and center console, they just seem too round since the car is designed with straight lines in mind. Same with the gauge cluster. The 96 seems like more of an old persons interior whereas the 95 seems like a driver oriented cockpit.

I'm going on a road trip with some friends later this year and we're either going to just hit Vegas or tour the whole country including Florida where my friends "really cool" uncle lives so if I'm in FL I'll PM you on here or something.

Night Wolf
06-11-05, 12:31 AM
Wow! quite the post :)

Gosh, there are lots of tire places, hell, I probably had a spare tire of that size around here, I could have drove the 45minutes to you and drop it off!.... man, so close...

I thought there was more of a difference with OBDI and OBDII, guess not though...

It seems like you ran into lots of problems :( IMO, that is something i would love to do, cross country, pick up car, drive back etc.... but like you said, I think being at least 18 would be best...

I dunno, I wouldn't get rid of the '78, I mean, the killer of these cars is rust, and if yours dosn't have any, then, IMO it is still a great car... honestly you could get a 425 from a junkyard for next to nothing, atleast have it running... or beef it up with a 472/500.... that '75 is one hell of a car, and I really wish I had a '75/'76 Coupe DeVille, but I gotta say, when it comes to building something up, the '77-'79 is 1,000lbs lighter, slightly smaller, and more nimble.... which in turn makes it a much better car for doing a street performance type build with...

the manual trans thing with me... I dunno, I think it is just becuase it is new to me... I know in traffic i would hate it... no more driving with 1 hand and drinking a soda with the other, no more spirited driving with 1 hadn on the wheel and 1 out the window etc... I think the auto is much more practical...

I have been thinking about the new car thing too, and everytime i see a newer car that I like, even nothing fancy, but there are a few I really like... it makes me think... but then again, I would love to keep the '93 going... hell, around here there are not many cars older then 1985 due to rust, but in FL....gosh, I have never ever see so many 60's and 70's cars being used as daily drivers, so seeing that makes me believe there is MUCH more life left in the '93 to carry me along, the Olds will still be a knock around car and the '79 is the hot rod car...

The real reason why I wanted a newer car or the Eldo, honestly is stupid things like the interrior, or the full gauges etc... So far every other thing I have not liked about the '93 DeVille, I changed, and right now, what i do not like is the bland gauges.... a speedo and a fuel gauge...yay!.... hell, I put the tach in the '79 DeVille and it keeps me content, So what i am going to do is buy another tach just like the one in the '79, and also buy a triple gauge cluster.... I want to orientate them within the car so it looks clean and, not factory... but not tacky.... then out of wood probably I will make a nice case, I really want the full gauges, and since I am pretty sure the car is coming to FL with me, I want it to be exactly what i want... to hell with keeping it origanal or anything... not like I am going to be ever selling it....

06-11-05, 09:01 PM
Put some more spunk into it... (http://www.cad500parts.com/)

06-12-05, 07:09 AM
Yeah that was a really long post, but you're still the king of long posts. :p

I have some thinking to do on the 78. I know it would need a lot of new parts. Headliner, seats redone, carpet, dash, rear deck cover, non-busted engine, paint, vinyl, maybe bumpers since they both are a bit dented. Which will run at least $2000 if I want to do it right. Plus I have to convince my parents to let it take up space in the back yard until I can "restore" it. There's not a speck of rust on the whole car, it's been a West Texas and New Mexico car its whole life.

Then I'd have to choose which car to make fast. I like the 75 because pretty much no one has a fast FULL-size, 2.5+ ton Caddy. The 77-79s and even some similar 80s are pretty popular for 500 swaps, like you, KwikCad500, and Lux Hauler for example. So the 75 is more unique, plus people will be even more impressed or at least confused if I can get it into the 13s. I *think* the 75 will be exempt on emissions this year or next, but it will be 3 more for the 78. Then again if I run propane I'll probably pass anyway even with a big cam and tons of power. But like you said, there's a ~900 pound weight differance which means if I can get the 75 to run a 13 flat, the same engine in the 78 will run a 12.2. I could always swap the 75's 500 into the 78 and drive it while I build up an engine for the 75 if I pick the 75 to hot rod.

But then I have to ask, do I really need the 78? I have the giant car I can hotrod in the 75, and the relatively good on gas 95 for a daily driver. So many things to consider, no matter what I do I'll probably never be sure I made the right decision. Unless I inherit a ton of money or something and hotrod the hell out of both of them, or put one on 20" spinners and hot rod the other. :)

I could also go with a fuel economy cam in the 78 and run propane, and at propane's cheap prices I could effectively get the price equivalent of over 20mpg city. I could even go with a manual trans since a 500/425 or maybe even a 368 8-6-4 with a mileage cam wouldn't kill one and I'd still have decent performance. But then why would I need the 95? In kind of the same way since you have the 79 to hot rod and the 93 as a good daily why would you really need a newer car?

SO MANY things to think about. Damn there I go writing another monster post...

I hear you on the thing about bland, uninformative instrument panels... The 78 and 75 both only have a speedo and gas gauge. I'm thinking about doing the exact same thing with building a wooden case for some gauges for the 75 or maybe 78. If I ever go wild and make a liquid propane injection system it will have a corresponding computer built into the car that can display all the engine info I could ever want.

Oh yeah, I broke my left rear wheel today in the ETC dirty style. The wheel and hub actually broke off the car which was left sitting on the control arm. Coming around a turn too fast and wet pavement cought me off guard and I hit a curb. Fortunately all I need (hopefully) is a new spindle/hub and rotor, and maybe a caliper and an alignment. If the bolt pattern/offset is the same I will be rolling on a full size spare from my friend's Buick until I can find a new rim or just buy 18s like I want to.

Night Wolf
06-13-05, 03:01 PM
Hmmm, seems like you '78 isn't TOO bad, like I was saying, rust is the killer, you don't have any, that is a great start...

The headliner on the '79 was replaced right before I bought it, I need to replace it in the '93 DeVille because it is dirty, has been since i got the car, and is now *starting* to fall on the edges and leaves finger marks. The headliner on the Oldsmobile is now completly fallen...

I did some research, www.WLSheadliners.com for about $50 shipped, I will get the material, glue and everything needed to do it myself, so I am going to wait until I have the $100 or so and just buy both kits, I was reading the thing, and it sounds plenty easy enough too....

The '75 DeVille is among my favorite Caddys, besides the '68 since the 50's.... I just love the styling, the front end, the sheer size of it... it is a sedan though, right? for me its gotta be a Coupe.... honestly, I wanted a '75/'76, but got a great deal on the '79.... I have often thought about selling my '79 for a '75, but decided to go against it.... but the sheer size and mass of that car is so cool, the quarter panel on the Coupes seems to go on forever.... the one thing i do not like at all, and where the '77-'79 really passes the '75/'76 is, the interrior.... IMO the interriors on the '75 are horible, they look cheap and I just don't like it... starting with '77, they are, IMO far better, better layout, better design... maybe because growing up, the same general interrior has always been around me (father had a '79 Coupe DeVille a long time ago, mother had an '84 Sedan DeVille 7 years ago that got wrecked, then got an '89 Brougham that she still has now)

I should get a picture of the '76 Coupe DeVille at the junkyard.... it got hit hard in the right quater, right around the wheel, the whole side is hit in well beyond the tire, and the whole driver side was side-swept... still, no glasss is broken, the doors open fine, from in the car, it looks fine, the interrior is fine except for the fact someone now hacked the whole dash up, and someone also played a sick joke by removing the hood springs, I swear the hood on that thing weighs 200lbs, it took alot of strength just to lift the damn thing...

I think either way you should keep the '78, like you said, first car and stuff, and it is a classic, pretty much all cars of this era are gaining in value, if you really were set on making the '75 go fast, then just get any ho-hum 425 from the junkyard and put it in the '78, then do something cool, like you said, bling it out with spinners (IMO stupid... not my type) or maybe build up a crazy sound system, put a computer in it with MP3, upgrade the speakers/tweeters, dynamat, and put a crazy subwoofer system in it.... then it really dosn't matter how fast it is, you can blow out the windows on whoever pulls up next to you :)

I put a tach on the steering column of the '79, it fits perfect, blends perfect and everything, I am happy with it... if I was to add a triple gauge cluster, I have seen someone add it on the ledge above the center AC vents... yeah it requires you to drill into the dash, and kinda looks tacky, but in a performance car, it fits, and is actually a good spot.

That sucks about the ETC.... hit a curb? ouch... definitly not cool at all... I hope you get it fixed though, what are you driving until then?

06-14-05, 03:34 AM
Yeah the headliner isn't a big pain to fix, in fact I could be lazy and leave it as is since it's stapled to the backing plate. Its just so many other things. But I've decided I will be at least keeping it in the back yard until I can afford to fix it up. I could build a custom center piece of the dash for it (would probably have to, either that or replace the whole front of it) so fitting some gauges in there wouldn't be hard and I could make it look cool.

Yep the 75 is a 4 door. I like it a lot, even better than the coupe, because there's no B pillar. If I had a sunroof in that thing it might as well be a convertable. The interior isn't great (well I like the seats) but eventually I'd probably re-do it with real wood. I also will definately convert the front seats so the back can fold down, making a giant bed out of the interior of the car. Having both types of cars I can say the 75-76s are better in every regard I can think of except the dash. Although it does have a better 100mph speedo.

I've always wanted to see a car with spinners do a crazy smoking burnout. Some 20" with spinners wouldn't look too bad on the 75 since it's so damn huge.

I'm going to the junkyard tomorrow to pull a spindle/hub assembly for the ETC... for $125 :( and I need a new rotor and possibly pads since my friend kinda messed them up pulling them off today. I don't have a ride now, but I don't have a job or anything to do either. But the ETC should be back up and rolling by tomorrow evening, even if it's rolling on a steel full size spare borrowed from my friend's car.