I apologise for this pic.... it doesn't show much. It's just the only one I have of it right now.



This is a 1977 Mercury Marquis Brougham.
It's powered by a 460cubic inch(7.5litre) V8. The transmission is a 3-speed automatic C6. I'm not sure what the rear end is exactly but I know it's beefy looking!
She's currently running a 4bbl 600cfm Edelbrock Performer series carb which is the only real "mod" that's been done to it.
My baby here is currently suffering from a massive loss of oil from somewhere. There's no smoke from the engine that I can see.... I'm thinking it's a leak but it doesn't seem to loose much just sitting. It can end up as much as a quart low from under 300 miles of driving.. not good. I'm currently looking into pulling the engine and doing a total rebuild. Also wanting to tweak some stuff a bit while I've got it apart.. things like aftermarket cams and porting the heads/intake are what I'm leaning towards. I don't want to dump thousands into it or anything, just tweak it a bit. If anyone here knows the 460 really well and can give me some hints I'd greatly apreciate it.
The other thing that I'm looking into right now is a repaint of the whole car. I'm going to change the color but not so dramatically that it won't match the interior.. just wanting to go towards a darker green color, something that's going to be dark and shiney Gonna talk to some people monday about both of those things.
If there's interest I'll take some more pics from different angles and such and post them here.

7.5 liters? Holy crap! How fast is the beast?

Well, faster than it looks for sure. This one only has an 85mph speedo and I can burry it behind the dash so that you can't see the needle at all. My 76 had a 120 speedo and I do that I had it up to 115 but I don't remember ever actually going faster. I'm sure it would do 120 based on that experience but it needs a long road to get there. One of the problems IMO with it performance wise is it really needs another gear in the tranny. The other one is that IT'S HUGE
Still.. I made a trip that was something on the order of 2600+ miles with it once, running 80MPH most of the way. She was getting a little over 15MPG when I checked it... about average for the car. People always tell me I should be getting single digit milage with it but it's never done so poorly for me. Maybe I just know how to drive it

a sidenote to that 2600 mile trip... I didn't know it at the time but when I made that trip I needed a new radiator. no leaks but it wasnt cooling enough, the 460 puts off a LOT of heat. Car overheated a couple of times. sometime after that the oil loss started. I actually ended up putting a quart in at every gas station. It has since improved but it's still bad. That overheating most likely wasn't good for it. before then she didn't use a drop!

SlkrKM...please don't tell me you're impressed every time you see a 460...they're everywhere, if you look around enough.

Cowman....nice car. It definitely has a 9" rear...send me your axle code off your door tag and I'll look it up in my '78 shop manuals. It's likely to be either a 2.75:1 or 3.00:1 as these are luxury cars and not dragstrip terrors.

I've rebuilt a couple 385-series engines in my day...although I don't know where you're losing your oil! 385-series big blocks are noted for having bad valve seals, but since you're not reporting major blue smoke, I doubt it's that. PM or e-mail me with ways to help the 460 without breaking the bank.

Pat

I'm only 18, so I wasn't around during the glory days of muscle cars. I'm more used to 4 and 6 bangers buzzing around.

The largest engine I have ever experienced is the 350 on my my dad's '92 GMC pickup.

same here I"m only 18
I saw 460 and almost fell outta my chair

didn't that older Lincoln Continentials have the 460s in them ?

Older Lincoln Continentals, Towncars, Mercury Grand Marquis, and Ford LTD's all had the 460 as an option thru the late 70's. Early 70's were standard w/ 460 engines. The early 70's cars with 460's were quite impressive, for example, a 69-71 Lincoln Continental Mark III Came standard with 365 Horsepower and an insane amount of torque. With the government and EPA closing in, It was a downhill climb after that. By the end of the seventies, the 460 made an embarrasing amount of horsepower / torque.

Why not locate a early motor with the 10.25 to 1 compression, or better yet a complete car. Try looking for a complete parts car for the early engine, (i.e. a MK III or full size Continental, up to '71 model year), you could do a rebuild on that motor while still driving the Merc.

In the meantime, try replacing the valve stems as was mention on the existing motor. You don't have to remove the heads to do the job.

The old hi compression 460 engines can tolerate today's 93 octane, provided that inital timing is retarded a few degrees from factory spec. I know this from first hand experience. I would be careful when selecting a camshaft so as to not put the engine into preignition due to too much cylinder pressure.

gmtofd

I got 12 mpg with my 400 powered '78. So I'd say 15 mpg is pretty good. Although my '78 was badly out of tune at the time. My Grandma claims she got 18 out of it when she was driving it all the time when it was new, but I'm going to have to see that myself. If you really want good highway mileage without killing performance, consider putting an E4OD transmission behind that 460. After having two cars with overdrive, I've spoiled myself to it. I would do it to mine, but with the 400, I'd be spending a lot more $$$ getting the electronics to work. As is, I'm just going to replace the FMX with another FMX, and hope someday to afford one of those nifty Gear Vendors overdrive units.

To try something cheap and easy about your oil consumption, try putting some Marvel Mystery Oil in each cylinder and letting it sit overnight.

It sounds like you have either seized the oil rings on the pistons, or fried the valve oil seals.

MMO will free up stuck rings (it may take several applications).

If you think it's the valve seals, they can be easily and cheaply replaced by you with just a few tools.

A shop would charge you about $100-$150, I think.

Probably the best thing to do first is to have the engine checked out by a good shop. They'll need to check cylinder compression to see if it needs a rebuild or just a set of seals...

Yes, 460 cid. I will tell anyone, that will listen, that my personal kharma is in closest alignment with the universal life forces when I am driving a car with 8 cylinders each about the size of a liter pop bottle. It really does not matter what brand of motor (FLM 460, GM455 or even Mopar 440, but bigger is always better. Gota get me one some day......

Still plenty of 500 inch Caddys around.

Single digit MPG's were on 73-74 cars. In those years, they just threw on anything for emission controls. 75-78 big cars got better mileage from electronic ignitions and catalysts.

The huge 74-74 MK 4's and Wagons got like 9 mpg, maybe.

The worst EPA rating ever for a US car was 8 mpg on a 74 Olds Toronado with a 455 and FWD.

"69-71 Came standard with 365 Horsepower" Yeah, but...

Before 1972, SAE gross HP was used, not the newer SAE NET hp measurement. Not a fair comaparison to today's cars.

Look it up, I've explained this too many times in the past 25 years.