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340 swap

Engine Swaps

  1. BudW

    BudW Moderator Staff Member

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    Back in early/mid ‘80’s, I replaced the 318 2-bbl in my ’67 Satellite (about a 4,000 pound or 1,820 KG car, or about the same as a M-body) with a stock 340. I reused the stock A727 from behind the 318. The 340 transmission will allow engine to rev higher between gears before shifting, so I had to do a lot of manual shifting to keep engine up in the higher RPM range. The car also had 3.23 gear ratio.

    I had little problem with the changeover – after I found the correct kickdown linkage and correct left mount. Everything else carried over from the existing 318, including the A/C compressor and the super heavy crank pulley (with rubber insert) from the 318. ’67 318’s was the first year of the LA design.


    Things I would have done differently, now:
    I love the 340’s and they are a great engine. With the 360’s out there, the twenty extra cubes are worth the effort to use.

    A stroker kit to even get more inches out of your engine is better – if you can afford it.

    3.23 gears are the highest I would use. 3.55’s or lower would be MUCH better. I wish I had changed gears to 3.55's, way back then.

    Get the governor set out of a 340 A727 (or another performance A727) or police governor set out of a A999 - so transmission will allow the extra revs automatically (sic).

    There is nothing wrong with 340 or 360 cylinder heads – but they just don’t cut the cake compared to the Magnum style heads when it comes to air flow.

    So, if I was going to install or build a performance small block, I would find a 360 truck Magnum engine. Maybe install a stroker kit into it (if within your budget), get a car 360 car oil pan and use that for my engine. I might want to reinstall the ’70-92 LA style timing cover so all external engine parts will attach – but there is nothing wrong with using the Magnum timing cover, so you can use the serpentine belt system.

    A person has all kinds of options – but I would still change your differential gear ratio FIRST and go from there.
    BudW
     
    Ed Dorey likes this.
  2. 5th avenue Rob

    5th avenue Rob Active Member

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    Very well stated. I intend on doing an intake and carb swap with an 8.8 ford rear and exhaust. All parts that can be used on my 5.9 later. Do the cheap stuff first but dont buy parts twice.
     
  3. BudW

    BudW Moderator Staff Member

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    Good advice.
     
  4. Poly

    Poly Well-Known Member

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    With the 904 ? With the expense and work involved with the 340 I'd expect some beefing up of the 904. This is one place I've saw recommended before. It was in a hotrod article a while back. They do carry many upgrade parts for the 904.

    Chrysler 904 Trans - A&A Transmissions
     
  5. 5th avenue Rob

    5th avenue Rob Active Member

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    On a side note. My magnum 5.9 lunched my 999 in about 2 months. Too many burnouts. The 340 has less low end but it is something to thonk about.
     
  6. Duke5A

    Duke5A Well-Known Member

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    Heh, when I had a 360 in my car I couldn't keep the 500 (basically an a999 only with overdrive) from eating itself either. I put so many bands into that transmission. :D Once I swapped to a 518 it was happy days again.
     
  7. 5th avenue Rob

    5th avenue Rob Active Member

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    I have a 518 thats going in my 5th ave along with a pre magnum roller 360 out of a 91 truck. I think some cutting is required for it to fit.
     
  8. BudW

    BudW Moderator Staff Member

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    There is one advantage to using the A998/A999 (or A500, which is 4speed version of the A999) transmission over the A727 and that is the low gear ratio.
    Note: most, but not all, A904 has the same low gear ratio as A727’s has. Very few A904’s share the same low gear ratio that A998/A999/A500 use – so if you know you have an A904, it is most likely to have the not so favorable low gear ratio in it.

    Gear ratios for A727, A518 (first 3 gears) and A904 (except for the very few A904’s mentioned above):
    First gear 2.45 to 1
    Second gear 1.45 to 1
    Third gear 1 to 1
    Reverse 2.21 to 1

    Gear rations for A998, A999 and A500 (first 3 gears)
    First gear 2.74 to 1
    Second gear 1.54 to 1
    Third gear 1 to 1
    Reverse 2.21 to 1

    The A998, A999 and A500 has a much desirable low/first gear ratio and it of itself is worth to use behind a performance small block. They can be built to take the abuse – but the question is how much you want to spend.
    The A727 and A518 are stronger transmissions (and heavier) from the start and by design can take more abuse.

    For full race, I would go with the A999 because of the gear ratio and for weight.
    For full street – I could go either way - mainly depending on differential gear ratio.

    For big block users, you are stuck with an A727 (or perform a Sawzall operation to make it a modified A518 – OR fit something else in its place (GM product)).

    For those still using a high gear ratio (2.2 to 2.9) – the 2.74 to 1 is a big help.
    Those using a low gear ratio (3.23 or lower), either would work fine.


    On an unrelated note, the front pump seal is leaking on my ’77 wagon (318 2-bbl A904 2.94 gears). The only way to fix it is to remove the transmission. I need to get this fixed before it gives out on me.
    My plan is to rebuild a ’84 A999 (police) I have in my garage - so I can have the low gear ratio (better takeoffs), I will have a bit better (higher) shift points and I can also get lock-up (which came out mid-year 1978) for better fuel mileage.
    The problem I currently have, is wife has other plans for my spare time – so what can I say . . .
    BudW
     
  9. 5th avenue Rob

    5th avenue Rob Active Member

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    That explains why my plymouth was so damn fast. It moved out very good for 1965 plymouth fury. Must have been close to 4000 lbs. Would smoke the tire at 30 mph roll. Is there a low first gear kit for the 518 or 727. Sorry if off topic.
     
  10. Duke5A

    Duke5A Well-Known Member

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    No there isn't. If you're going 518 then you can just lower rear gear to compensate. 4.10's are a hell of a lot of fun and still perfectly driveable on the express way with the 0.69 overdrive.
     
  11. BudW

    BudW Moderator Staff Member

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    Opps, I thought I had mentioned that point, but after re-reading, I left that part out.

    At one point someone was making an aftermarket gear set, but the company didn’t stay in business very long – so no, no known gear changeovers exist for the A727 or A518.

    With an overdrive transmission, you can go with a lower differential gear set and then use overdrive for those long-distance trips (although, your overdrive won’t be as much of an overdrive – it is still the best of both worlds, so to speak.

    That is one of the reasons I want the 6-speed TR-6060 Tremec Magnum (manual) transmission.
    It is basically a normal 4-speed with two overdrives – but built to take the torque of a V-10 or a big block (the top end Mustangs, Camaros and Challengers use them).
    That way I can have a “fun” differential gear, like say 4.10’s and still drive across state without worry.

    Something to think about with those of us with (or will have) stroker engines.

    A person does have to get an expensive bell housing to use a T56, TKO or a TR-6060 (small or big block). The TR-6060 is an upgraded T56 and is a better choice if a person is looking for a 6-speed – but is also a bit more expensive. Even aftermarket bellhousings are about $700-800 (US) for one.
    BudW
     
  12. 5th avenue Rob

    5th avenue Rob Active Member

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    Yah. My 7" rear will be toast by the time I get to the trans
    Good time to swap in the 8.8 ford rear and 3.73 gears.
     
  13. AJ/FormS

    AJ/FormS Well-Known Member

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    Hector
    I told you wrong, for 4100 ft elevation
    that 10.5-340 with a 270* cam will have plenty of torque, more than your 318,also at 4100.
    The numbers for the 340 come in around...... 10.5Scr/8.42Dcr/153psi@122VP,
    while your 318 at sealevel, is rated................ 9.0Scr/7.71Dcr/ 156psi@ 125VP,
    with a 252/112 cam,but at 4100,
    Your current 318 numbers might look like;......9.0Scr,7.71Dcr/134psi@ 108VP,

    So when you say something is holding your teener back, there it is; a total loss of VP, at 4100 ft. The Hi-Compression 340 would restore your low-rpm performance to that of your teener at sealevel, while simultaneously increasing your power every where else. The downside is that 270* cam will suck gas pretty hard, especially in your heavier car, and it will require some supporting mods; like headers,etc.
    I'm sorry Hector, for being a jerk; the numbers don't lie

    As to your teener;

    You can also get a pretty good boost in low-rpm power, by going to a shorter period cam.But you will lose power at higher-rpms, say after 35mph. If that doesn't sit well with you, then
    The best solution for the current 318 is higher compression,at 4100ft,lots more.
    To still be able to burn 87, I suggest 10/1 with a 252/112 cam.
    This will get you;(4100ft)..........................10.0Scr/8.55Dcr/156psi@125VP
    As you can see,this will restore your teener to sea-level spec power.
    But as said, the cheapest solution (not the best solution) is more rear gear. Going from 2.75s to 3.55s is a boost of 28.6%. your current combo might be generating a VP of 108. If you gross that up by 28.6% to 139, you will get an idea of what your 318 would feel like with 3.55s; the performance will be something like a stock 5.9Magnum with 2.76s, maybe better. Of course the 3.55s will cost you fuel economy.
    And a close second cheapest solution is a higher stall TC. I suggest a much higher rpm Convertor, to let your current 318 spool up to where the power is.I bet yours is down near 1700, which might drag your max power available, down to 50hp. With a 2800( the lowest I would go) you might find between double and triple that, for a very nice boost in take off power.

    As to the 5.9Magnum@9.2Scr,my opinion as to using a 360 still stands. It will have the same or better low-rpm power, as the 340, for your 2.76s, while not as hard on gas
    Just for comparison;with the same 252/112 cam, burns anything, and looks like this.................................................................9.2Scr/7.92Dcr/140psi@127VP
    If you bumped the compression up to............10.0Scr/8.59Dcr/157psi @146VP
    Check out that VP, now up to 146@4100, and still burns 87
    That will really wake your car up, even with the 2.75 rear gear
    But there's more. The 5.9Magnum gives you the potential for even more power.
    To burn 91@4100,the 360 is easy to build at; 10.9Scr/8.85Dcr/164psi@144VP
    This would take a cam with an ICA of 62*, which could be something like
    270/276/108/56* overlap,or
    266/270/110/48* overlap, or
    262/266/112/40*overlap, or
    258/262/114/32* overlap

    The less overlap, the better the fuel economy, and the wider the powerband, at the expense of absolute power..... and vice versa

    And going back to the 340, you could pull that 270* out of it, and install a cam with a 56* ICA for a Max pressure effort of .. 10.5Scr/8.85Dcr/165psi@139VP, that needs 91 gas. Or one of those 62* ICAs listed above for an 87gas friendly ........................................................................10.5Scr/8.5Dcr/155@124VP
    So if the 340 was cheap enough to purchase, a cam swap might make it more economical to operate

    But you just got to compare the VPs of the 340 at 155psi to the 360 at 157psi. In your heavy car, I'd take the 360 anyday.
    And 146/108=plus 35%; that is HUGE !
     
    Last edited: Jul 22, 2018
  14. Oldiron440

    Oldiron440 Well-Known Member

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    For about $1500 you can put a small turbo on your 318 and it will be a rocket at 4100 feet.
     
  15. Oldiron440

    Oldiron440 Well-Known Member

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    If you spend more you can get better parts.
    At that altitude a turbo should be part of any package you put together,
    318, 340 or 360.