I have an opprotunity to buy a 80 or 81 deville with that "great" engine. Should I stay away ??

kinda depends on if its a 80 or 81 in 1981 was when they did that 8-6-4 stuff and 80 was just carb I think thats how it was plus the 8-6-4 can always be disabled. from what I've read on here its a decent little motor heck if the cars in good shape the engine can always be swaped out for one of the big boys I pretty sure they're a blot in swap

The 8-6-4 is easily disabled. Mine has been solid throught the years.

My friend's 81 Eldorado was flawless, little vibration on 6, but decent mileage and ran great.

I went to check that car out today and I drove it. Man,it barely moved my 85 eldo with that 4.1 could beat it.

I drove the car today and man what a dog my 4.1 can beat it off the line. Us it supposed to be like that or is there an issue with the 368

368 vs HT4100 is like battle of the low powered V8's in big, heavy cars :).

Still though, a 368 should have a handful of more power then the HT4100.....

A 368 8/6/4 in proper tune will keep up with a carbonated 425 in the same chassis. The car which you drove must have problems.

Problems like a tune-up or stale gas or something more involved ???

Yes. Tunep. The 368 has WAY more torque than the 4100, 265@1400 to be specific.

It's not fast, about 10 second 0-60.

A 368 8/6/4 in proper tune will keep up with a carbonated 425 in the same chassis. The car which you drove must have problems.

425 has more hp and more torque... same tranny, same car... how would they be the same?

How is the 368 on fuel w/out the V8-6-4?

Toward the end the 425 had 180-190HP. Torque was in the 300s, thought not at that low an RPM.

The gas mileage on the non modulated displacement engines was typical of a 6 liter V8 for its time - fairly bad. Do not forget that they DID have 3 speed transmissions, so no overdrive.

425 has more hp and more torque... same tranny, same car... how would they be the same?

8/6/4 cars had a 2.41 axle ratio verses 2.28 in the 425 cars. Vehicle weights were about 150 lbs less. 8/6/4 had fuel injection. They keep right up. I had plenty of tests back in the day.

Toward the end the 425 had 180-190HP. Torque was in the 300s, thought not at that low an RPM.

The gas mileage on the non modulated displacement engines was typical of a 6 liter V8 for its time - fairly bad. Do not forget that they DID have 3 speed transmissions, so no overdrive.

I currently own a 1980 368 Fleetwood. The thing gets the best fuel economy of any carbonated car I've ever owned. 19 MPG on a steady highway trip 65 to 70 MPH. Around town it is pretty bad. Also have a 1980 CDV with the same engine. It only gets 14 MPG on the highway on a good day. Both cars pass emissions. The CDV has a lot of carbon buildup in the intake valves I suspect.

425 has more hp and more torque... same tranny, same car... how would they be the same?
actually the 81 has a different tranny thm350 not thm400

my 81 w/ disabled 8-6-4 gets 13 city, 24 @ 55, 17 @ 70

actually the 81 has a different tranny thm350 not thm400

'81 still used the TH-400.

Eldorados didn't... I think they had a THM350. I have to look.

Eldorados used the TH325... the TH350 is RWD.

'81 still used the TH-400.
80 did but i am pretty sure the 81 used the 350c

81 V864s used the TH400.

Yes you are right.

Now I know what tranny I have in my 81, thanks guys.
KC.

..im pretty sure that 368 ci 6.0 litre was made in 1980..i just want to know how does that car run..if anyone has one reply to this please.. cause im thinking about getting the 1980 368 ci non v-8-6-4 and i bet it would get alright gas milage compared to my 79 425 ci but i think that this car would overall be a great car cause it aint the bad press that the v-8-6-4 got and its just the straight 368 ci so anyone tell me how this car runs i really want to know how good they are overall

I have 2 carbonated 368 cars right now. Both run great. Neither runs as good as an 8/6/4 car that it working properly but you can drive them to the moon and back without worries.

Our 81 8-6-4 sits for months on end in summer and winter, and it always starts regardless of the temperature outside. Thanks for the excellent input Ape Man, we really enjoy your support for these engines.
KC.

Our 81 8-6-4 sits for months on end in summer and winter, and it always starts regardless of the temperature outside. Thanks for the excellent input Ape Man, we really enjoy your support for these engines.
KC.

Happy to help while I still remember this stuff.

I used to have an 1981 Eldorado with the V8-6-4. Only sold it due to having too many cars and I'm sorry I did. Never had any problems with the V8-6-4 feature and it had 116,000 miles when I sold it. There was a slight vibration in 6 cyl. but, this was common due to the unbalanced cyl. number, four running on one side and two on the other. I found however, that the computer prefered either 8 or 4 anyway so it was never an issue. Great car that delivered 20+ MPG on the highway if you were careful. The power was decent; it produced it's peak torque at 1,400 RPM. The best part about the car was the quiet and refined ride, I drove it everywhere are never had a problem.

In mine, been up, been down and all around. Never ever defeated the 8-6-4 feature, and the car always performed well. The cosmetics on the car leave a bit to be desired, and a few problems cropping up do to age. With only 102,000 km on the car, it is just barely broken in. May have to sell it do to lack of cash and time (kids/wife/blah/blah).
KC.