engine mods
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Thread: engine mods

  1. #1
    Fellow Frogger!
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    Default engine mods

    i am rebuilding a new engine for my brothers r12. i've got a complete 1.4 motor and all the parts for a total rebuild, though i was wondering if there were and small performance mods i can do without spending much more money?
    also, which or the 12 boxes has the tallest final drive ratio? i have a 75 sedan box, an 80 virage wagon box, and another 12 sedan box whos model is yet to be identified (i think 72).

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  2. #2
    Fellow Frogger! Jensen's Avatar
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    G'day,

    Ive had my 1.4 in my R10 for a few months now and im most impressed with it. The head had already been opened up and shaved etc so cant help with exact details there, but i got the cam from Wade in Oakleigh, Vic. They had three grades on record, i went for the mid one as its driven on the road every day. Its a little cammy, really starts to pull at around 4000, but compared to the standard 1108 its still got heaps of torque down low so im happy. Still getting really good fuel economy, all though the high comp motor dislikes anything but premium.

    With a cam, a bit of headwork and the motor rebuild (are u using new pistons and liners?) it should go a bit better. My cam was about 90-100 bucks plus whatever u want to spend on the head, u should get a bit more performance for a reasonble price.

    Good Luck

    Jensen

  3. #3
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    Probably the most simple and economic mods to a 12 would be a simple port and polish as well as matching the manifolds as well as a full engine balance. Basically these motors run really sweetly and forever with few mods.

    Then again, it all depends on what you want to do with the car, there are side draft Weber manifolds and esxtractors available, as well as cams, but I reckon that they spoil the all round nature and economy of an everyday 12.

    The diff ratio for the '74 sedan and '80 Virage is the same 9x34, however the '75 model 12 gearbox, usually 352-32, has a taller first gear.

  4. #4
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    the car is just a daily driver. i don't want anything too wild, just enough to pull it up the hills with a little more ease. but then it has been running on what can only be described as two and a half cylinders. also i was after a taller final drive for highway use. did any of the 12's have this?
    besides that, my brother will kill himself in it if i go too wild. he thinks that driving is about going as fast as possible, braking as late as possible, and having the tyres produce as much noise and smoke as possible.
    at least this way it'll be done with a little class as opposed to in a bloody commodore or falcon.

  5. #5
    Simon's Avatar
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    No 12's had a higher final drive, but you could always pop in a 17TL gearbox which has a higher diff ratio (9x32) by swapping the bellhousing, but I reckon that may be a bit too tall even for a 1.4 with just a tad more torque than a 1.3 12. Pulling up hills would suffer, but it would make an excellent top speed cruiser!

    Even with a ball tearing 45kW, given the full boot, a 12 can make a lot of noise courtesy of FWD on stock 155x13's so hopefully that should keep him happy and safe! :-)

  6. #6
    1000+ Posts REN TIN TIN's Avatar
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    The other possibility is fitting the 5 speed type 395 box our of an R18. You will find discussions about this in the past on this forum.

    Basically it would involve swapping the bellhousing and input shaft (easy). You would need to make a custom rear mount (pretty easy), and customise the gear linkages (not so easy).
    The biggest problem is that the drive shafts would need to be shortened. I've heard it rumoured that someone in Melbourne (Caravelle, maybe) sells shortened driveshafts. It is allegedly possible to swap the diff from the 352 box into the 395 box to keep the standard R12 driveshafts.

    Ren
    "I cannot help but notice that there is no problem between us that cannot be solved by your departure. Mark Twain"

  7. #7
    Simon's Avatar
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    Quote Originally Posted by REN TIN TIN
    The other possibility is fitting the 5 speed type 395 box our of an R18. You will find discussions about this in the past on this forum.

    Basically it would involve swapping the bellhousing and input shaft (easy). You would need to make a custom rear mount (pretty easy), and customise the gear linkages (not so easy).
    The biggest problem is that the drive shafts would need to be shortened. I've heard it rumoured that someone in Melbourne (Caravelle, maybe) sells shortened driveshafts.
    Ren
    One thing forgotten here, the floorpan of the 12 will require modification to the hump to accomodate the longer 5th gear gearbox too, unless the car has been an auto in the past and has a big hump floor. From what I have heard though, performance with a stock 12 and this conversion is disappointing, the gearing is too tall for the 1.4 although it does give good economy.

    Also it is French Connection that does the shortened driveshafts.

  8. #8
    Fellow Frogger!
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    Default engine mods

    ok i have done some work to my 12 with a 1.4 motor.
    I have also just swapped to a very late model 12 box which has longer 1 st and 3 rd not final drive howevr last of the 12 boxes has awesome gearing. Now a motor mod if want and can get is aset of 12 alpine pistons and sleeves or what they calleda v85 alpine motor which was in spansih a11o alpines the have domed pistons and look similar to a 12 motor from the outside .
    the difference is 12 alpines had a crossflow head where these alpine motors do not .
    Port and polsih the haed which i have had done if u have an ealrier model 12 with a 1289 cc use the same manifolds as virages have more antipolloution gear . Get your carbie rejetted using carbie fro m1.4 motor and swap internals to ealier model carb it works a treat.
    I got a set of extractors makes a difference and a decent exhuast system 2 helps .
    If u can get a early 12 engine pipe as it is 2 pipes drom naifold then goes into one underfirewall i caN GET U OINE OF THSE IF U NEED late 12 s one pipe from manifold all the way.
    Another things is get dizzy checked get a bosch dizzy and recureved to run on premium i race my 12 and she pulls 105 mph down straight at phillip island.
    u wANA NO MORE EMAIL ME [email protected]
    classic no plastic just lots metal but lots of fun

  9. #9
    Simon's Avatar
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    Quote Originally Posted by daniel the r12 nut
    ok i have done some work to my 12 with a 1.4 motor.
    I have also just swapped to a very late model 12 box which has longer 1 st and 3 rd not final drive howevr last of the 12 boxes has awesome gearing. Now a motor mod if want and can get is aset of 12 alpine pistons and sleeves or what they calleda v85 alpine motor which was in spansih a11o alpines the have domed pistons and look similar to a 12 motor from the outside .
    the difference is 12 alpines had a crossflow head where these alpine motors do not .
    I thought that the V85 motor was basically a 12TS 1.3 clone apart from a few minor differences as the compression for both motors was 9.5:1. There was though some Renault Competition pistons that were domed for the 1289cc motor. These are of academic interest only though if you have a 1.4 block, as the 1.4 block is o-ring liner seals and the 1289cc block is paper liner seals.

    Also I'd warn against swapping the 3rd gear alone for a higher gear ratio that can be swapped from other gearboxes. In my opinion there is a big gap between the stock 2nd and 3rd and that gap is only emphasised on the track. Altering 3rd alone would only emphasise the gap between those ratios. And on the road the bigger gap between gears could be embarrasing in tricky situations.

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