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Discussion Starter · #1 ·
Like I mentioned yesterday, I’m a new fifth avenue owner, and I’ve fell in love with my 87, however I love to learn more and interested in learning more, please don’t get tired of me and all of my questions lol, what’s the easiest, cheaper way to just keep the original 318, but beef it up and make it sound and drive like a true v8, cause the 318 that’s stock and in the car is a turd, is that normal for a stock 87 Chrysler fifth ave 318 to be a turd, it runs strong with under 100,000 miles, it’s my first v8 and I’d like to get it to run an also sound like one
 

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You don’t want to start with “more power” or you will be bound for disappointment.

The car’s performance is hampered by a 2.2 gear ratio in a rear axle that is likely waiting to explode (assuming it has the 7.25” rear axle common to these cars).

So the first upgrade needs to be to 2.9 or 3.2 gears in an 8.25” rear end (the donor can be an F/J/M car). There are other options, but this is the closest to a bolt in, requiring nothing more than shortening the driveshaft and changing the speedometer gear. There are other options, but more fabrication is required.

Once you run it with a proper gear, you’ll be much more pleased with the performance and can then start other modifications if they are still desired. The stock engine with a better gear will outperform a modified 318 with the stock gear. Trust me, I got a heck of a deal on a modified car with stock gearing because the guy spent a lot of cash and the car remained a slug.
 

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Thank you, what exactly is fjm I know my old jeep had the 8.25 rear end
F = Dodge Aspen/Plymouth Volare
M = Diplomat, 82 and up Gran Fury, 77-81 LeBaron, 82 New Yorker, 83 New Yorker Fifth Avenue, 84-89 Fifth Avenue
J = 80-83 Cordoba, Mirada, 81-83 Imperial

Most of the cars above had 7.25 or 8.25 rear ends. Finding a better ratio can be hard as many had the 2.2. The 2.9 was used in any 318-4 cop car (but not the 318-2 ones). Many slant 6 cars had 2.9 gears, but a lot of them got the 7.25 axle. Look in earlier cars for better ratios especially with performance options. You may find a 3.2 geared Aspen or Volare.

The Jeep 8.25 rear is different than the car in its mounting system.
 

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Discussion Starter · #6 ·
You most definitely know your stuff I appreciate it sorry for all the questions I’m really trying to learn I love my fifth Avenue I just wish it wasn’t a turd but I’m definitely on the lookout for a different rear end
 

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You most definitely know your stuff I appreciate it sorry for all the questions I’m really trying to learn I love my fifth Avenue I just wish it wasn’t a turd but I’m definitely on the lookout for a different rear end
It's not a turd for what it is. None of those 80s sedans were performance-oriented. You have to remember that there actually was a market for large, plush sedans. These were intended for long interstate trips. The tall gears provided decent fuel economy.

With regard to swapping the rear axle assembly, it won't be easy. 20 years ago, it started to get to being pretty slim pickins for the 8 1/4 rear in the boneyards. You'd do better to look for another 7.25 in a slant six car, as those had either a 2.76 or the 2.94 gearing. 1979 was the last year for the 3.21 gears in the 8.25.

Now, I'm going to pee all over this parade. Going with a shorter (numerically higher) rear gear could add some zip, but it also creates 2 big problems - noise/drone, and poor fuel economy. Because these cars did not have an overdrive transmission, top gear was direct drive. The lockup convertor helped, to a degree, but with stock 205/75/15 tires and 2.94 rear gearing, you'll be turning that motor substantially higher at highway speeds. That creates quite a bit more drone from the exhaust, and it totally kills the point of driving a classic luxury sedan. Worse is that by keeping the RPM in a higher range, it will use quite a bit more fuel. And the 2bbl cars were supposed to use premium fuel. Ask yourself if it's better to get it running really well, tuned to factory spec. Nice and quiet, decent mpg. Or do you want a loud fuel hog that you'll get really tired of filling up everyday.

The best, most cost effective thing you can do with these M.bodies is to keep them stock. When they're all tuned up and the computer is happy, they run very well. You can't put 2022 expectations on a vehicle that was last produced in December of 1988.
 

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When I swapped form 2.2 gear to 2.9 gears in my 1982 New Yorker Fifth Avenue, I really maintained the same overall gas mileage.
The car was a low mileage (60k) car I bought in 1996. The previous owner had problems with the torque converter lockup and a non-lockup transmission was installed (so the lower first gear was not present in the replacement transmission).
My normal driving was a mix of stop and go and freeway driving with weekend trips on the open road. With the 2.2 gears, the car lugged around town. With the 2.9 gears the lugging was gone.
Overall, the gas mileage average was still the same after a swap from a 2.2 geared 7.25 rear to a 2.9 geared 8.25 with Sure Grip . I'm sure the 2.9 gearing improved gas mileage in town and took some way on the open road. The car remained quiet and smooth through the factory exhaust with the new gears and stock 205/75/15 tire size. The Sure Grip was nice since I drove the car year round in Ohio weather.
I really did not see any downside to the swap, especially since I had a wrecked police car with the 8.25. I know it is harder to find an 8.25 now, especially with 2.9 gears but they are out there.
Another good source for an 8.25 with better gears is a slant 6 Aspen/Volare/Diplomat/Lebaron wagon. All the wagons had the 8.25 rear.
 
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A shorter gear for primarily short trips won't affect mileage as badly, and will help keep it from carboning up. Fuel economy is far more dependent on the driver, but running any internal combustion engine at higher RPMs will always result in higher fuel consumption - it takes more fuel to increase the RPMs. With any engine, there's a sweet spot in its RPM band where it's most efficient, and that will vary from car to car. That's why the key thing to remember is more RPM requires more fuel.

Higher RPM also increases interior noise levels. This can be mitigated, somewhat, by careful selection of exhaust components and mounting it up so it's all isolated from the body or other components. You can also add a ton of dynomat, but that's as much of a band-aid as putting a shorter-geared rear end is with these cars.

We keep beating this dead horse, and nobody wants to listen. These are great cars, and you get the most enjoyment out of them by taking the time to learn all about them, and fixing them up like new. They were not engineered or intended to be any kind of performance models, including the squads - those were designed to be durable, reliable work vehicles. For most of the time they were in production, the national speed limit was still 55 mph. There was no need for a 400 hp V8 in a retail sedan in those days. They were built for an expected lifespan of 10 years/100,000 miles. The squads were expected to last 150,000 miles.

Things are very different today, and the younger enthusiasts will buy one of these cars, and immediately think that because they're a classic, that they're all hot rods. That just isn't the case. But they still tear them up until they hit the inevitable concrete wall of mismatched parts and/or exhausted budget, and they wind up on Marketplace for obscene money (ran when last parked!).

If anyone insists on tearing up yet a other intact M body, here's my advice:

- Make sure you have money. You can do a lot of good work with a $5000 budget. You will absolutely ruin it for only $500.

- Create a plan. What is it you intend to do, and why. Read our advice here, read Rick Ehrenberg in MA, read the factory service manual, get a feel for what works and what's right for the car and your budget.

- Understand that the factory fuel and ignition systems are probably as good as you'll ever get on a little 318. Adding a huge 4bbl carb or a crazy expensive ignition system won't give you much improvement - if any - over a properly tuned factory set-up. Unless you have full headers, a 340 cam, and crazy short rear gear, you're wasting money.

- On a lower budget, if a guy had $1500, you could actually go the smarter route. Find a good 360 Magnum in the boneyard. Maybe $500, tops. Find a used carb intake for it, and a good used thermoquad or Qjet out of a Dodge pickup, and rebuild that. Maybe $250 there. You need the correct flexplate or convertor weights for the engine, and the correct kickdown rod or a new kickdown cable. Even with the weak sister 7.25 out back, you can still run it and enjoy the torque. Save up for a good 8.25 rear, but keep the ratio tall, no more than a 2.76 or 2.94. Build, or have someone else build, a new single exhaust, 2.5 is just fine for a 360. You should be able to put all that together for less than $2500. And you'd actually have something you can enjoy for a long time.
 

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Just to give an idea:

My 92 Dakota has V-6, 4-speed overdrive auto and 3.55 axle. When it sometimes sticks in 3rd gear, which is direct drive, at 65 mph it's running about 2800 RPM. This is the same as you can expect from a 3-speed Torqueflite with 3.55 axle, and it's about the same engine speed that I had with my 72 Dart slant-6. So if your axle ratio ends up being 3.21, you will be in better shape than that. And power should be very good.
 

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Just to give an idea:

My 92 Dakota has V-6, 4-speed overdrive auto and 3.55 axle. When it sometimes sticks in 3rd gear, which is direct drive, at 65 mph it's running about 2800 RPM. This is the same as you can expect from a 3-speed Torqueflite with 3.55 axle, and it's about the same engine speed that I had with my 72 Dart slant-6. So if your axle ratio ends up being 3.21, you will be in better shape than that. And power should be very good.
There wouldn't be a huge difference between the two shorter ratios, maybe 150 RPM. Either way, she'd be wound up pretty tight at 70-75 mph on the interstate. The limits of the engine and exhaust do limit the sum of any actual gains that can be realized. The ELD 318 2bbl is a torquer. It has 15 ft-lbs more torque than the ELE 4bbl engine, and at a lower peak RPM. With the stock 302 heads and the corked up exhaust, if you gear it really short, you'd reach the point of negligible returns very quickly. And again, and as we all know, that same money spent on a good used 360 and its components will provide for the miles of smiles that everyone really wants.

The fact is, most of the questions we get about these cars here revolve around performance, and few have the actual budget it would take to give the cars good, reliable performance. Thus, the reason I continue to strongly advocate for these new owners to learn about the cars, their various systems and quirks, and what it will take to restore them to factory spec. Anyone who's owned and driven one of these M bodies that's been properly repaired and tuned will attest to the fact that they have excellent drivability, good fuel economy, and are quite reliable. You just aren't going to be able to run with real late-model performance models. They simply weren't designed to do that. Nor were any of the F, J, R, or later B or C bodies (except the 440 squads).
Anyone can make a vehicle quick or fast. It just costs money. Lately, it costs a lot of money, provided one can procure all the parts.

So, there's a method to my madness, and I'm sticking to it. Every year that goes by, we lose more and more of the older cars. But we also lose the history in the engineering and design that went into them. The newest of the M bodies just turned 33 model years old this past September first. They aren't ideal for daily driving anymore. They make a great toy for cruising. If someone wants to go fast, they should really buy a car that was built to go fast. It's not that much different than all the questions we get regarding putting a 5.7 in a 3.6 car, or trying to soup up the 3.6. We tell them almost the same thing - leave it stock, save your pennies, and buy a V8 car.
 

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I got a low mileage, totally stock '83 5th Ave from my uncle's estate sale in about 1991 and found the 318 to have a surprising amount of power and the economy was amazing.

I picked it up in ND, increased the tire pressure when I refueled and headed for Seattle with the trunk jam-packed and back seat filled to the ceiling with household goods. Even the front seat area was filled to the point my elderly mother had to hold some things in her lap. Needless to say, I was dreading to hit the Rocky Mountains, but to my surprise it pulled the passes without a whimper. Even more surprising was the 20 mpg it got on that stretch of highway. Overall, we averaged over 22 mpg. I don't know what gearing it had, but it was the right one for me.

I drove and loved that car for about 4 years with not a single problem. When I moved to Texas in '96, I had to sell one of my vehicles, and decided to keep my '73 D100 so I could move everything in one vehicle. It was rather stodgy in appearance, but it was super comfortable, quiet, and reliable. I sure miss that old Chrysler!
 

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I got a low mileage, totally stock '83 5th Ave from my uncle's estate sale in about 1991 and found the 318 to have a surprising amount of power and the economy was amazing.

I picked it up in ND, increased the tire pressure when I refueled and headed for Seattle with the trunk jam-packed and back seat filled to the ceiling with household goods. Even the front seat area was filled to the point my elderly mother had to hold some things in her lap. Needless to say, I was dreading to hit the Rocky Mountains, but to my surprise it pulled the passes without a whimper. Even more surprising was the 20 mpg it got on that stretch of highway. Overall, we averaged over 22 mpg. I don't know what gearing it had, but it was the right one for me.

I drove and loved that car for about 4 years with not a single problem. When I moved to Texas in '96, I had to sell one of my vehicles, and decided to keep my '73 D100 so I could move everything in one vehicle. It was rather stodgy in appearance, but it was super comfortable, quiet, and reliable. I sure miss that old Chrysler!
It had the 2.2 gears. All the civilian v8 cars did beginning in 1980. There were no optional gear ratios.
That gear made them a good highway car and a poor car to drive in town. Beginning in 1981, they lowered the first gear ratio in the transmission to give the cars a little more kick off the line, but it also meant a larger jump to second gear where you could feel the engine struggle for a second at times.
 

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Discussion Starter · #16 ·
There wouldn't be a huge difference between the two shorter ratios, maybe 150 RPM. Either way, she'd be wound up pretty tight at 70-75 mph on the interstate. The limits of the engine and exhaust do limit the sum of any actual gains that can be realized. The ELD 318 2bbl is a torquer. It has 15 ft-lbs more torque than the ELE 4bbl engine, and at a lower peak RPM. With the stock 302 heads and the corked up exhaust, if you gear it really short, you'd reach the point of negligible returns very quickly. And again, and as we all know, that same money spent on a good used 360 and its components will provide for the miles of smiles that everyone really wants.

The fact is, most of the questions we get about these cars here revolve around performance, and few have the actual budget it would take to give the cars good, reliable performance. Thus, the reason I continue to strongly advocate for these new owners to learn about the cars, their various systems and quirks, and what it will take to restore them to factory spec. Anyone who's owned and driven one of these M bodies that's been properly repaired and tuned will attest to the fact that they have excellent drivability, good fuel economy, and are quite reliable. You just aren't going to be able to run with real late-model performance models. They simply weren't designed to do that. Nor were any of the F, J, R, or later B or C bodies (except the 440 squads).
Anyone can make a vehicle quick or fast. It just costs money. Lately, it costs a lot of money, provided one can procure all the parts.

So, there's a method to my madness, and I'm sticking to it. Every year that goes by, we lose more and more of the older cars. But we also lose the history in the engineering and design that went into them. The newest of the M bodies just turned 33 model years old this past September first. They aren't ideal for daily driving anymore. They make a great toy for cruising. If someone wants to go fast, they should really buy a car that was built to go fast. It's not that much different than all the questions we get regarding putting a 5.7 in a 3.6 car, or trying to soup up the 3.6. We tell them almost the same thing - leave it stock, save your pennies, and buy a V8 car.
 

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Discussion Starter · #17 ·
Before I do anything the coolant system needs a good flush, which I’m on my way home from work to do, the only problems other than that I can’t figure out is when going from park or reverse into drive, it jumps a little bit, if I go all the way to 2nd and then to drive it doesn’t seem to do it as bad, and the gas pedal is pretty hard to press, any idea on what this could be??? Thanks a lot for the info I’ve already received
 

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The gas pedal effort, unless something is binding, is a result of the springs on the carb linkage under the hood.

The idle speed may be a little elevated which would cause the harsher transmission engagements.
 
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