R12 Head Porting
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  1. #1
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    R12 Head Porting

    Greetings Regie Revheads.

    Does the R12 1289cc head respond well to porting? I've got to lift mine to get the guides sorted, and looking at a spare head the other day, the exhaust ports look tiny, especially about 30mm in, where there is a slight lump constricting it. I've got some experience with porting and manifold/port matching. Any hints? As it happens it tends to run a bit rich I think (is this normal with the stock Weber?) so should respond well to more air flow. There seems to be a fair bit of material to work with too...(revs up drill and burr with mischeivous glint in eye).

    Cheers

    Stuey

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    2003 PEUGEOT 206 GTi

  2. #2
    Simon's Avatar
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    My 12 runs the standard spec head, and has no problem revving to 7,200rpm. At that stage it gets a bit breathless understandably. I think it just needs a bigger carby like a 40 DCOE sidedraft on a Lynx manifold.

    The stock car doesn't run rich unless it is out of adjustment or worn. My car has 260,000 on the original Weber carby and still runs nicely.

    However there is a mile of metal in the ports to play with as can be seen when the manifold is removed, so matching the ports would be quite simple and could produce good results.

    Simon
    1963 Renault R4 Van
    1964 Renault R4
    1967 Volkswagen 1300 Deluxe
    1969 Renault 8 Gordini 1300
    2002 Land Rover Defender Td5 130 - ex-CFA Region 4
    2005 Renaultsport Clio 182 Cup

  3. #3
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    7,200 rpm? What else is done to the engine?

    Stu


    2003 PEUGEOT 206 GTi

  4. #4
    Simon's Avatar
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    Nothing, this motor is stock, apart from a rebuild with a new piston/liner set 80,000k's ago. I wish I had it balanced, it worked wonders with my 4. Another reason I like the old Sierra based motor. But the later 1.4's just don't seem to rev the same way.
    1963 Renault R4 Van
    1964 Renault R4
    1967 Volkswagen 1300 Deluxe
    1969 Renault 8 Gordini 1300
    2002 Land Rover Defender Td5 130 - ex-CFA Region 4
    2005 Renaultsport Clio 182 Cup

  5. #5
    Simon's Avatar
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    I‘ll just add that there really is not much point revving the poor 12 motor to 7,200 apart from the nob factor of saying it can be done and flashing off to impressionable people :-). The power drops off rapidly after 6,000, so a bigger carby, valves and extractors would probably do wonders in the way that an 8G is better than a normal 8 and a 5G has more performance than a 12! But really I don't have a problem with how it presently performs.
    1963 Renault R4 Van
    1964 Renault R4
    1967 Volkswagen 1300 Deluxe
    1969 Renault 8 Gordini 1300
    2002 Land Rover Defender Td5 130 - ex-CFA Region 4
    2005 Renaultsport Clio 182 Cup

  6. #6
    Fellow Frogger!
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    Feb 2002
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    Fellow Revheads,
    I can confirm the benefits of porting & matching on the R12 heads.

    My son had a R12 (1289CC) engine in his R10, which had a professional job done on the head re port matching etc. It also ran extractors, had a Collier spec cam (with roller bearings) and a 40 DCOE Weber plus cold air box.

    Allowing for the fact that double valve springs were also fitted, 8000 RPM was no problem. The get up & go factor was very impressive, as was its ability to simply cruise on the open road with reasonable fuel economy.

    It remained a very reliable car, and was mainly run on Optimax or equivalent (plus Morey's). Yes, the 1.3 motor is a much more willing "revver" than the 1.4, due mainly to the physics of the 1.4 motor having to overcome the greater inertia of a heavier crankshaft, flywheel etc. The aforementioned R10 had a lightened flywheel with a stepped face to give increased bite on clutch engagement.

    Cheers,
    Kim.

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