Delving into a 403 engine
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  1. #1
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    Default Delving into a 403 engine

    I started work on the best engine I have which was reasonably intact although missing the small iron sump cover.
    The plugs were nearly past extracting with rust and gunk, but I got them out.
    Then off with the head, to find water and rust in cylinders and a couple of cam followers.
    But with Inox and a bit of work I got it turning and then took out the piston that had dislodged it's sleeve.
    Amazed to find it has two compression rings and two oil rings, the lowest being down near the skirt. I've never seen this before. Is this a special engine?
    The conrods look as if they've been polished as well.
    The bigend bearing was almost perfect with only one slight scratch and the journal looks brilliant, still covered in oil.
    I'm thinking the sleeves may only need a light hone and the same bearing size might be able to be refitted.
    That plus a head job sounds like a cheap reco.
    But please tell me about these rings.

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  2. #2
    Fellow Frogger! Phil Whitton's Avatar
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    Default bits

    Voila , rings a bell without referring to the w/s manual. I did up a 403 donk to fit into the Bug 43B replica much to the consternation of the Histerical Registrar. All the ally was mottled and polished. .
    Finished up ( i think) in the Barker Peugeot.

    I still have 4 X 404 donks complete if you need some bits

    bon chance

  3. #3
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    What I don't get in the manual is the lack of valve timing setup.
    Sure it gives all the technical specs and how to use special tool number xxxx, but it doesn't give a proper way to line up the dots.
    I'm much more of a dot liner upper type of guy. I don't get off on setting up dial guages and timing discs, much rather set it as it should be from marks aligned correctly.
    But the manuelle doesn't give that info, so I'll just have to reinstall the dizzy, see when it points to number 1 on tdc, and make a mark to remember where the camshaft should be pointing.
    Apart from that it's the simplest engine in the universe.

  4. #4
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    Quote Originally Posted by Phil Whitton View Post
    Voila , rings a bell without referring to the w/s manual. I did up a 403 donk to fit into the Bug 43B replica much to the consternation of the Histerical Registrar. All the ally was mottled and polished. .
    Finished up ( i think) in the Barker Peugeot.

    I still have 4 X 404 donks complete if you need some bits

    bon chance
    Yeah thanks for the offer Phil, nice bike there, is it a duc?
    I could be needing an oil pump and possibly a harmonic pulley and crank handle nut.
    I have a couple of other motors but I had a good heave on the pulley nuts with the big stilsons tonight with no effect. I'll try heating with the oxy but if all else fails..... I might be on your doorstep with hat in hand.

  5. #5
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by luthier View Post
    What I don't get in the manual is the lack of valve timing setup.
    Sure it gives all the technical specs and how to use special tool number xxxx, but it doesn't give a proper way to line up the dots.
    I'm much more of a dot liner upper type of guy. I don't get off on setting up dial guages and timing discs, much rather set it as it should be from marks aligned correctly.
    But the manuelle doesn't give that info, so I'll just have to reinstall the dizzy, see when it points to number 1 on tdc, and make a mark to remember where the camshaft should be pointing.
    Apart from that it's the simplest engine in the universe.
    403 cam timing is set up with a (useless) pug tool. There are no dots or marks.

    This is a cut and paste from another thread:

    There is a method however. It is only known to work for standard cams.

    With the engine ready to time

    1) Put cam followers in 1 inlet and 1 exhaust
    2) Put a second followers upside atop of the other 2
    3) Bring number 1 cylinder to TDC
    4) Rotate the cam until a straight edge across the top of the followers is parallel to block face.

    Fit the timing chain.

    This method was shown to me by my brothers mate Brian Thomas. Brian was an engine builder par excellence and ran the crank grinder for Norm Gown and others.

    Same difference as Isy's method. Only works for symmetrical cams, which standard cams are.

    Ed Iskenderian has forgotten more than most people will ever know about camshafts.
    The less one interacts with rude, ignorant, critical and argumentative members. The more peaceful life becomes.

  6. #6
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    Quote Originally Posted by luthier View Post
    I started work on the best engine I have which was reasonably intact although missing the small iron sump cover.
    The plugs were nearly past extracting with rust and gunk, but I got them out.
    Then off with the head, to find water and rust in cylinders and a couple of cam followers.
    But with Inox and a bit of work I got it turning and then took out the piston that had dislodged it's sleeve.
    Amazed to find it has two compression rings and two oil rings, the lowest being down near the skirt. I've never seen this before. Is this a special engine?
    The conrods look as if they've been polished as well.
    The bigend bearing was almost perfect with only one slight scratch and the journal looks brilliant, still covered in oil.
    I'm thinking the sleeves may only need a light hone and the same bearing size might be able to be refitted.
    That plus a head job sounds like a cheap reco.
    But please tell me about these rings.
    Need a special tool which works well otherwise use Robs method but check that the combined height of the pairs of can followers is the same in each case.
    If it has 4 sets of rings it is possibly a 203 engine, does it have 75mm pistons with domed tops?
    Some 403 pistons had a 4th ring below the piston pin.

  7. #7
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    It's 80mm diameter pistons with flat tops and the extra oil ring is below the gudgeon pin. Definitely 403.
    That's the thing I've never seen before.
    Is that a particular motor? Seems like a good idea.

  8. #8
    Member mmnarelle's Avatar
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    Default Piston rings

    I had a 1938 Buick 8 straight 8 that I sold about 8 years ago...I rebuilt the motor and was amazed to find a very similar ring set up..the pistins were quite long (like the preverbial "slugs) with an extraring right down at the bottom of the piston.

  9. #9
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    Quote Originally Posted by mmnarelle View Post
    I had a 1938 Buick 8 straight 8 that I sold about 8 years ago...I rebuilt the motor and was amazed to find a very similar ring set up..the pistins were quite long (like the preverbial "slugs) with an extraring right down at the bottom of the piston.
    I know, it takes you by surprise, I've rebuilt 3 403 engines but they were all conventional with 2 compression and 1 oil ring.

    I wonder about your 8 scenario. 38, 8, 8, 8, perhaps 8 is your numerological number. It's a good one. Aren't they all?

  10. #10
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    I took a shot of the unusual ring layout I found.
    Sent the photo to Neoretro as they have a listing for four rings per piston, but the photo they show has only three. I told them they were welcome to use my pic for their catalogue, but they must have been pissed off because they said they don't have a ring set for me.
    I was only trying to help.

    Désolé,nous n'avons pas votre modèle de segmentation

    But it doesn't matter, because when I pulled the others out I found that one piston had let go it's top ring and the edge of the crown was missing.
    So I'll just be fitting a standard sleeve kit with normal rings.
    O well, I thought the four ring idea had merit, but it's not to be for me.



  11. #11
    1000+ Posts Wildebeest's Avatar
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    Luthier,
    Are there any markings on the piston crown or under the skirt. They may have been supplied by an Aus after market company. Repco. Dufor etc?

    Not uncommon for early ie pre-war engines to have the ring below the gudgeon.

  12. #12
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    I actually bought a 4 ring set of pistons and liners for an engine I built from Neo Retro!
    Probabl;y not a great idea, increased friction and if you've got good quality rings not neccesary.
    Graham



    Quote Originally Posted by luthier View Post
    I took a shot of the unusual ring layout I found.
    Sent the photo to Neoretro as they have a listing for four rings per piston, but the photo they show has only three. I told them they were welcome to use my pic for their catalogue, but they must have been pissed off because they said they don't have a ring set for me.
    I was only trying to help.




    But it doesn't matter, because when I pulled the others out I found that one piston had let go it's top ring and the edge of the crown was missing.
    So I'll just be fitting a standard sleeve kit with normal rings.
    O well, I thought the four ring idea had merit, but it's not to be for me.



  13. #13
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by luthier View Post
    It's 80mm diameter pistons with flat tops and the extra oil ring is below the gudgeon pin. Definitely 403.
    That's the thing I've never seen before.
    Is that a particular motor? Seems like a good idea.
    My Renault 4CV has a Repco sleeve kit (so they might have made them for Peugeots in the 1950s-1960s too). That kit came with 4-ring pistons, although the factory ones were indeed three-ring pistons. The fourth ring is down the skirt, just as you describe.

    I have a set of new rings from USA too, and there are four per cylinder.

    So maybe not so odd. Maybe it's had a sleeve kit in earlier times.

    Cheers
    JohnW

    Renault 4CV 1951
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