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1K views 9 replies 7 participants last post by  davesdeville 
#1 ·
So I purchased this eldorado http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=4613280789&sspagename=ADME%3AL%3ARTQ%3AUS%3A1,http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=4613280789&sspagename=ADME%3AL%3ARTQ%3AUS%3A1

and it should be here in a couple weeks. Looks like its in great shape and is truely intended as a weekend cruiser. I understand im looking at about 8mpg which is ok, i can afford it. Are there any tips that might net me a 50% increase?

That got me thinking to diesal engines. This car seems like an ideal candidate for a diesal swap. I have read about the olds diesal and how awful it is. Have others swapped out a better diesal (isuzu, or the like)? I found a whopping 4 listings for "diesal" in my forum search.

Anyways, hello!
 
#2 ·
When I bought my '73 Eldo, many many moons ago, it was giving me 10 MPG. I brought it up to 13 by putting a curve kit in the distributor, turning the air filter cover upside down (can cause carb icing at 40-50 deg with high humidity) and mainly by putting radial tires on it.

That is a beautiful car. Only 9K on the clock? WOW! I think that is exactly what I paid for mine ($5200). It was red with 5K on it but that was in 1975 or 76.
 
#3 · (Edited)
Will Albers said:
So I purchased this eldorado http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=4613280789&sspagename=ADME%3AL%3ARTQ%3AUS%3A1,http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=4613280789&sspagename=ADME%3AL%3ARTQ%3AUS%3A1

and it should be here in a couple weeks. Looks like its in great shape and is truely intended as a weekend cruiser. I understand im looking at about 8mpg which is ok, i can afford it. Are there any tips that might net me a 50% increase?

That got me thinking to diesal engines. This car seems like an ideal candidate for a diesal swap. I have read about the olds diesal and how awful it is. Have others swapped out a better diesal (isuzu, or the like)? I found a whopping 4 listings for "diesal" in my forum search.

Anyways, hello!

Hey, it is your car and you can do anything you wish. However, I would not change the engine if I were you, if for the only reason that the car is so nice and original in appearance. You have claimed that the price of fuel is not an economic issue for you, so with that, and the original condition of the vehicle, I would leave it as is and try the suggestions Ranger gave.

The use of a 500 C.I. engine in 1973 was not to impress but to deliver massive amounts of torque at low RPM. Your only alternative is a modern Diesel engine coupled to a modern overdrive transmission which still maintains the same aspect ratio of the original 1973 configurations. That is not very likely.
 
#4 ·
No offense, but that's a bad idea if I ever heard one. First thing, did you buy this car for fuel economy? I hope not. Second thing, it's FWD. Meaning you'd have to find a diesel that'll mate up to a BOPC pattern TH425, and fit in the space a 500 fits. You'd have to do some funky custom engine mounts to work with the TH425. You could cut up the bottom of a perfectly good car and convert it to RWD but that would be even more of a pain in the ass. Either way you'd have to change the fuel system of the car body. Good luck getting the Cad accessories to play nice with the diesels belt system. And in the end you're looking at going from 12-13 city with a 500 to perhaps 16 with, say a 6.5TD in that chassis. Are you willing to pay $5k to get 3-4MPG more? The ONLY good thing about a diesel would be that it would be very similar in RPM range compared with the 500.

Anyway, on things you can do to increase your fuel economy. First thing, grab a junkyard HEI distributor, clean it up and give it a new coil, cap and rotor, recurve kit, and other parts like vac. advance unit as needed. This will be the single best thing you can do for fuel economy in that car.

Last tank in my 75 Deville I got 10.9mpg. That was with me flooring it an excessive amount of times, and ALL city driving. This is with no carb adjustments for my 5500'ASL altitude, so it's running fairly rich as well. So, I'd say 13-14 city is entirely possible if you don't drive like a jackass like I do sometimes, have a good HEI with working vacuum advance, and your carb tune is fairly good.
 
#7 ·
If you really want to change the engine in that car, you'd be better off selling it! A classic car, especially one in that nice of shape deserves better than have it's classic powerplant ripped out, and replaced with a diesel of all things! I know you have good intentions for fuel mileage, but if that's the case, get a different car! Future car collectors will thank you!
 
#8 ·
Gents, ALL valid points! I was reading about some of the H1 diesal swaps yesterday and figured I would ask the question. I agree with your logic and it makes sense.

Sad thing is I did not realize this was a front drive vehicle!! for some reason I thought they started front wheel drive caddies in 75. I was wrong :)

I also appreciate the advice on tune up options. I had the HEI swap in mind, but has anyone found better results with a MSD system instead? I think i have one laying around.
 
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