360 into a 1984 Fifth Avenue

Engine Swaps

  1. Rustyroger

    Rustyroger Well-Known Member

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    I have picked up a 360 from a late '70s Dodge, a Mirada I'e been told. I would like to put it in my 1984 Fifth Avenue. Up date, apparently its from a truck.
    It's complete (2 bbl) carb to pan, including exhaust manifolds, distributor, and harmonic balancer, but no flex plate.
    I understand the flex plates aren't compatible, so I'll need a new one. are the oil pans a straight swap?.
    Apart from the above, any major issues or pitfalls to avoid?.
    I want reliable stump pulling torque for hauling my travel trailer rather than tire shredding hp, will I gain much from the 360 over the original 318?.
    How will the transmission fare with more torque and a heavy load?. I will be adding a transmission cooler of course, and have the radiator rebuilt with a heavy duty core.

    Roger.
     
    Last edited: Mar 1, 2017
  2. jasperjacko

    jasperjacko Well-Known Member

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    How heavy is your trailer, and does it have brakes? I would be more concerned about stopping it.
     
  3. AJ/FormS

    AJ/FormS Well-Known Member

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    Oilpans between these two do not interchange.
    The TC has a different balance requirement
    The passenger engine mount is slightly different but you can work with it.
    edit; the ECU will not play nice with the new engine. The Ecu controls the timing in response to the load it sees on the vacuum line. With a bigger engine, the load will always be less than what the computer was calibrated for, so the timing will always be wrong. How much wrong is anybodies guess.So the cure is a stand-alone distributor kit.end edit
    I think you would get better and cheaper results with a rear gear swap. Moving up to 2.76s will get you the same performance as the 360 with the 2.45s, and I imagine the teener will get the better mileage still; now cruising at 12.6% more Rs, or about 2300rpm@65mph with 205/70-15s. The trans-cooler is still a good idea.
    I inherited an 84 Fifth from my dad when his number came up in 2010. Nice hiway car.It had 2.45s,and it cruised right around 2000,IIRC. Very quiet too. He towed a Bowler with it. That's a funky-looking aluminum skinned camper trailer that does not fold up, and is tall enough to stand up in.
    He kept a diary for that car, and that shows the car consistently ran 25 mpgs-Imp, even in 2010 at 26 years old.That would be 20mpgUS. No not towing,lol. I put a timing chain in it for him a few years earlier.Dot-to-dot,lol
     
    Last edited: Feb 26, 2017
  4. AJ/FormS

    AJ/FormS Well-Known Member

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    OH dear, I see you are in the UK, and already have the 360.
    Since you already have it, Slam it in there. From this point on It's kindof a toss up as to money spent. I forgot to mention that 360 will not like your lean burn computer. I would bypass it, but that will cost you a couple of hundred for the kit, which includes the old style dizzy, the wiring, the resistor and the little ECU to power it up.
    The flexplate you already know about, and you can get those to work with a zero-balance convertor.
    The biggest problem I see is those low rear gears. I don't know what your car is running. It might be 2.45s, or it might be 2.2s. These keep the Rs down so far at cruising speed that when towing, the throttle has to be way far open. Depending on how far this gets to be, either engine may be well into the main circuit, and the lean burn may be pulling timing. That's a double whammy for poor fuel mileage.

    Keep in mind tho that there is just 13.2% difference in cubic inches between these two engines, and the 360 is up-cammed because of this.That means there is not 13.2% difference in torque at stallspeed. There is probably less.
    Also, a swap from 2.45s to 2.76s is plus 12.6% in torque multiplication, while from 2.2s to a 2.76s it is plus 25.5% And this torque multiplication is everywhere throughout the rev range, from as soon as the car moves an inch to shift rpm, or to blow-it-up rpm.It exists separate from the engine entirely.
    So if you have one of those cars with a 2.2 rear gear, the simple solution is 2.76s. If you already have the 2.45s then it's kindof a draw, but still favoring the 2.76s. Swapping rear ends is a couple of hours work.
    Rpm at 65 with 2.76s is about 2230rpm,still very comfortable.And there is lots of torque available in a teener at this rpm, in fact, very nearly 100% of what it can produce in it's 1984 trim.
    I have cruised many tens of thousands of miles at 65=2236rpm.
    If I had to guess, I think the teener with 2.76s will outpull the 360 with even 2.45s, from zero to 60mph, all other things being equal.If it doesn't it will at least be very close.
    Now, as to the 360 with 2.76s, now that would be a whole new story.
    So my first move would be the rear gears, cuz, basically I'm lazy,the install is fast and easy,and the numbers are favorable.If I still needed more torque, say to pass, then it would be 360 time. And then after all that, if I just really wanted to know, I would slam the original rear back in. By this time all the bolts know there way home and it shouldn't take more than 2 hours. Probably less if you skip swapping speedo gears for now.Theres only14 fasteners and the 2 cables. Block the brake pedal up and pinch the flex line. Boom! before you know you're done.
    I'm just trying to help
     
    Last edited: Feb 26, 2017
  5. Rustyroger

    Rustyroger Well-Known Member

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    Ok, thanks for the replies. Here is more of the story.
    I bought the car as a non runner a week ago, and the 360 engine as it was dirt cheap and easy to sell on if it wasn't suitable for my needs.
    The computer in the air cleaner is history, it wasn't in the car, still less in the air cleaner. I've put maybe an hour into getting it started, with a new coil it ran long enough to get it off the trailer but not round to my garage. It has a 2bbl Holley fitted, and lots of plugged breathers and vacuum lines. Quite normal for American cars in the UK that have been played with by amateur mechanics. My eyes were wide open to all this, I haven't been ripped off considering what I paid for it.
    I think reverting to a conventional distributor and setting up the Holley properly would be my best bet. We are not plagued with ethanol mix fuel over here, 95 ron unleaded is regular gas, with 98 ron available at a premium.
    If I go down this route any suggestions for basic timing, and recommendations for a good aftermarket distributor?.
    I hear what you have to say about the rear end, but getting hold of one isn't a question of simply going to the local Pick'n'Pull. There is a good following for Mopar cars over here, the Mopar Muscle Association, although it's fair to say more focused on Muscle Cars than boulevard cruisers. But no doubt they would be willing to help with tuning and parts.

    Roger.
     
  6. Rustyroger

    Rustyroger Well-Known Member

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    About 1800lbs, it has it's own braking system, braking the car makes the trailr hitch move, actuating the trailer brakes, known as run on brakes over here. This is pretty much standard fitment on most trailers over 450 lbs gross weight likely to be hauled by passenger cars in Europe.

    Roger.
     
  7. AJ/FormS

    AJ/FormS Well-Known Member

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    No computer is good
    Vacuum-advance distributor is good
    1800# trailer is heavy
    2.2 rearend is bad
    2.45 is a little less bad.
    both rears go down the hiway at 65mph being less than 1900 rpm.
    Both engines are gonna struggle to get going, as I think the TC in that car,with a healthy engine, is about 2200.
    >The 360 will have more passing power, when it kicks down a gear at 55plus mph. So if that is all you need slam her in there.
    But if you also need more grunt to get going, the stock 360 will not offer much,if anything at all, more, with that stock TC.
    Buuuut
    if you increased the TC stall speed, that would put either engine a little further up the rpm band right at start-off, and that would continue for a good long ways. Further up the rpm band means more torque/horsepower.I see that Chrysler used to sell at least three different rpm stall-speed, loc-up TCs. Perhaps you can source something like that in UK. This would not do much for the 318 as to passing power, cuz at 55mph, KD into 2nd is about 2400rpm, so a 2400 TC would help almost nothing for passing.The teener would like more stall for both start-up and passing.
    I think for you, the answer is to do both. Do both the 360 and a higher stall TC.
    1800# is nearly 50% more weight than the car was born with.Without rear gear help, I think both will be the answer.
    And I would put either dual exhaust on it or a big single,and I would upgrade the tranny guts (clutches and bands), and for sure a deep pan and an oil-cooler for it.
    If you still need more after this, I would suggest a cam for low rpm torque, something like the factory 2bbl teener cam. I think it would be ideal. In fact, I would put one in there right now!
    And if still not enough, then try and spot a Thermoquad somewhere and grab it and its matching iron manifold. Either size will work, with perhaps the 1.5s being the better choice. Even the 1.375 primaries should be enough to cruise 65 on, and the big back dumps will help the 360 fly when passing.But the 1.5s might be a tad stronger when off the secondaries.
    If you have never had one of these carbs, I tell you what; put a semi-automatic shift kit in your tranny that allows you to put it into any gear at any time. Then choose a TC in the 2600 to 2800 zone. Then get the car up to about 20 mph and stick her in third, and go hammer down. Towing 1800# from 20 to 65 in third gear, with the TQ moaning the TQ-moan for nearly a half a mile will set your face in a semi-permanent smile! And every time you pull out to pass, go hammer down just to hear that TQ-moan! oh yeah.
    After that,you may have to address the cooling system.
    But if the 360 is to be rebuilt, compression will be your friend.
    Tuning the carb will not be too big a deal.
    Tuning the ignition will be tricky,cuz going down the road with a low-compression engine,at 1700rpm(2.2s) to 1900rpm(2.45s),towing 1800#, there is almost no way to give that engine the ignition advance it wants.But you can get close.This combo is an ideal candidate for a dash-mounted,dial-back, timing box. With great gas available there,and a very low rpm cruizing speed, the box can allow the engine to receive up to 15 more degrees advance.
    Cruising at 1900 say, the engine might want in excess of 40 degrees timing. Well if you set the initial at 12 say and if the dizzy can bring a rate of advance to the table of 1 degree per 100rpm(a lot) then by 2000 rpm that would total perhaps 22*. Your current Vcan might be in the neighborhood of 14* but if the engine has to pull so hard that the vacuum falls below its ability to surrender it all,then,say it only delivers 10*. Now you are up to 32*. And still perhaps 10 short for towing, and perhaps 20 short for NOT-towing. The lack of advance just means crappy fuel mileage, cuz not all the energy in the fuel was delivered to the crank; some went straight out the tailpipe.This is where that little box comes in, with its ability to kick in up to 15 degrees electronically.

    So those are my thoughts, if the rear gears have to stay.
     
    Last edited: Mar 1, 2017
  8. Aspen500

    Aspen500 Well-Known Member

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    I wonder what 95 ron is in U.S. octane ratings. My guess is it's probably same as our 87 octane? Just curious is all.

    BTW, we can get ethanol free regular also and the majority of premium is non-ethanol only (at least in this part of Wisconsin).
     
  9. Rustyroger

    Rustyroger Well-Known Member

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    Thanks again for your input, AJ and Aspen.
    Second part first, I'll check out how our regular unleaded compares with yours. maybe I'm mistaken, maybe it's classified differently. However I'm under the impression UK regular gas is a slightly higher grade than the stuff ib the USA. Certainly the rental cars I've used in the USA seemed to have less sparkle than the same cars over here, though it's fair to say I'm just using my butt dyno, hardly a unbiased blind comparison. :)
    Interesting reading your post, AJ. I shall re-read it a few times, you raise some interesting ideas. The car will need a new exhaust, so I can get a good one made from scratch, my wife likes a nice V8 burble, I prefer nobody to hear me coming. So a V8 burble it shall be. Would an X pipe between a dual system help?.
    My local transmission guy is very good, and had a habit of putting Mopar V8s into Volvos and Mazdas in the past. I shall pick his brains about how best to set up the transmission.
    I guess I need to source a low ratio rear end, My '87 V6 Oldsmobile 88 made a fine tow car, in all honesty I expected the Chrysler to be better still out of the box.
    But forewarned is forearmed, right now I need to get it running enough to get it into my garage, where the engine is coming out to replace the freeze plugs, and a quick check over of the bottom end. Or not if I find any nasties, and the 360 will go in it's place.
    Is a well built 904 upto handling a beefy 360?, it will have a big cooler on it, and a heavy duty radiator, I want ice cold A/C as well!.

    Once again, thanks for your input;
    Roger.
     
  10. BudW

    BudW Moderator Staff Member

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    Installing a 360 into a ’84 5th Ave is not a big affair, but will require some parts, first.

    Externally, the engines are almost identical – which means pretty much everything on your existing 318 will bolt right to the 360 – with a couple of exceptions:

    The exhaust manifolds have larger ports (both on engine side and exit). I would recommend using the larger 360 manifolds and getting a new exhaust Y-pipe made that is slightly larger (maybe make the pipes ¼ inch larger (5-6 mm). That way you can get rid of the front two catalytic converters (if possible – not sure what emissions laws you have to work with there).

    Engine oil pan. Just find any car (not truck) 360 (center sump) oil pan. The 318 oil pan will not come close to fitting. One like this one would work great Chrysler Mopar 1971-80 Hot Street Rat Rod Oil Pan Raw Steel 360 Center Sump SB | eBay
    360 oil pan.jpg
    Note: you may already have a usable pan. Just make sure the sump looks like this (and not to either end).

    A “balanced” flexplate, so you can retain your existing torque converter (this is the best option, instead of replacing torque converter with one already balanced for 360 eng) B&M Automotive 10236 Flexplate FLEXPLATE MOPAR 360 W/TF727 TRANS.
    Flexplate.jpg

    The right side engine mount is wider on 340 and 360 engines, by about ½ inch (13 mm) – going by memory. You can use longer bolts and washers to compensate for the difference but finding the correct right side mount would be better 73 74 75 76 DUSTER 318 340 360 ENGINE MOTOR MOUNTS "PAIR" | eBay
    Mounts.jpg

    Your existing transmission is more than adequate for the 360 – just as long as you use a 360 balanced flexplate (or a 360 torque converter). The flexplate is the recommended option.

    Your existing 7¼” differential should hold up to a 360 2-bbl or a non-high performance 360 4-bbl – but is the weak link of the entire package, as you have planned.
    Getting an 8¼” (or larger) differential and at least have it under the bench, might not be a bad idea.

    Changing the differential gear ratio will be a big help, especially if towing. Your existing gear ratio should be 2.2 (or a slim chance of 2.4). Finding gears in the 2.9, 3.2 or 2.7 range will help, a lot – maybe as much as the larger engine will make, if not more.

    Your engine pulleys, P/S pump, A/C compressor, alternator, A.I.R. pump (if to be re-used) will all fit just fine.

    It appears you will need to find a 318 or 360 distributer (with vacuum advance) and ICM (Ignition Control Module). This (or one like it) should fix the ignition problem Proform Electronic Ignition Distributor Kit Mopar Dodge Chrysler 273 318 340 360 | eBay
    Ign setup.jpg

    A 4-bbl will let the engine run better – but will also come with additional parts to acquire, as well (Intake, carburetor, transmission kickdown linkage, air cleaner, and so forth).

    Note: the 360 2-bbl carburetor and the 318 2-bbl carburetor are completely different, as well as the bolt pattern on the intake manifold.

    If your existing 318 was Lean Burn - but no longer have the computer for it, then finding a non-computer controlled carburetor will also be on your list of things to get. There is a chance your 360 might also be computer controlled (will need to see a picture of it to tell).

    Before installing the engine – I would recommend changing the freeze/expansion plugs, replace most of the engine seals/gaskets including valve seals (head gaskets don't need changed, unless heads are removed) and at least check the timing chain for wear before installing. Once done, the engine should be good to go for a long time.
    BudW

    Note: the links I have above are from eBay. I just found them to use as an examples. Using that data, you may be able to find a source local or more cost effective to get to you. I am not promoting those links.
     
    Last edited: Feb 28, 2017
  11. 80mirada

    80mirada Well-Known Member

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    Right side motor mounts are the same between 318 and 360. The left side mount for a 360/340 is narrower than a 318, but a 318 one will work.
     
  12. Rustyroger

    Rustyroger Well-Known Member

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    Thanks Bud and 80.
    Bud, you have made lengthy and very helpful replies, I dare say you already noticed I have two threads covering more or less the same issues. A big thank you, already I'm much better informed about all things Mopar than I was a few days ago. :)
    Perhaps a moderator could join them together?.

    Anyway, I shall try to get pictures up soon, computer skills are something I have in a very limited supply.

    Roger.
     
  13. BudW

    BudW Moderator Staff Member

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    My cell phone takes wonderful pictures – but I have to downsize the pictures before I can post them.

    It took me a while to figure out how to post pictures, then it took me a while longer to figure out how to post the bigger pictures.

    Refer to this for instructions on adding pictures.
    Uploading Pictures
    The pictures I have in post # 10, I copied from the eBay ads I listed.

    Opps, aye, the 340/360 Left mount is narrower than a 318, not wider (my bad).

    I have replaced with larger engine using correct mount as well as using longer bolts and washers (have employed both methods). I still recommend the correct mount for I have had the longer bolts/washers loosen on me before. It might not be a big deal, sense there are 3 bolts holding mount to engine, but it annoys me for some reason (not what you do, but what I do/have done).
    BudW