203 air filter thoughts
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  1. #1
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    Default 203 air filter thoughts

    I'm in the process of fitting a standard 203 head and carby setup onto the 403 block. This boils down to the fact that I haven't been able to find a decent 403 head that's worth fixing. Therefore I had a 203 head welded and fixed with all new valve seats, fully unleaded friendly, with big buildup of alloy around sparkplug holes including inside each valve cavity, and I'm feeling fairly confident that this one will actually seal up and have reasonable compression.
    There have been problems setting it up because the rockers had to be 203 to fit the smaller diameter studs. I went through a couple of rocker assemblies and built one that seemed OK. Wrong! It wouldn't reach adjustment because the engineer put the valve seats in at a fairly thick dimension so the ends of the valves were too low. Fortunately I had another assembly which had enough adjustment.
    I found during this that 403 pushrods are shorter than 203.
    So all's well as I have enough adjustment on the rockers and I've organized the carby linkage.
    Then I found that one of the big tubes that joined air cleaner bits for the 403 setup went pretty well from the carb directly to the oil bath aircleaner. I was hoping this would be the case, but I haven't seen any 203 with this setup.
    Just wondering if it's a bad move for any reason? Living on a dirt road I'm thinking it will be the best idea for a filter. But the 403 setup goes through a long chamber first before sucking out of the oil bath. This goes direct.

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  2. #2
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    The biggest problem you will find using an oil bath filter is that the "air-rush" through the filter will suck up the oil in the filter. I have found this in the past and my thoughts on it are that the smaller valve heads in the 203 head give an increased gas flow with the "bigger" 403 bore, i.e. more gases are being expelled for the same valve openning duration but the hole it goes in or out doesn't have the capacity. You will probably have already noticed (if you have had it running) is the increase in "in-take" noise through the top of the carby.
    If you solve it let me know.
    I would also like to know if yu are using an original 203 carby or a 403 one?
    FLASH

  3. #3
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    Default





    OK Flash, thanks for that. I suspected that might happen.
    As you'll see here it is the 403 carb complete except for the throttle thingo. I asked Graham Wallis and he said it should be pretty well 403 carb to go with 403 block so I just put the whole thing on.
    Tomorrow I'll have it going so will know how it runs.
    If , as you say. it sucks oil, I'll revert to a standard 203 type paper filter.

  4. #4
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    Dan,
    I am told a paper element R324 fits the 403 oil bath container,
    you may have to pack up the bottom to ensure a seal

    send me a Pm re steering wheel boss please

    Colin

  5. #5
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    This is ours, 203 head on 403 block:

    [ATTACH]203 air filter thoughts-img_0068.jpg[/ATTACH]
    Attached Thumbnails Attached Thumbnails 203 air filter thoughts-img_0072.jpg  

  6. #6
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    Thanks Flash. Looks like I'm going to have to get a whole lot shinier if'n I want it to go right.

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    PM sent.

  8. #8
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    Came with the chrome rocker cover when Carolyn bought it from Geoff 30 (?) something years ago. The rest of the "shiney" put down to the talents of Carolyn's son who put it all together when he fitted the engine.
    Have a look at what they did in the engine bay on the gallery attached to their posted comment on the thread '403 Panel Van' (they masquerade as BERTHA403).
    FLASH

  9. #9
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    But what I don't understand Flash, is why you continue to run the air through the oil if it sucks it up?

    Or have you also got onto these paper elements that Alpine speaks of?

  10. #10
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    Unfortunately it only gets driven every other month so it is just "topped up" before every run. I like to call it "upper cylinder lubrication".

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    Quote Originally Posted by luthier View Post




    OK Flash, thanks for that. I suspected that might happen.
    As you'll see here it is the 403 carb complete except for the throttle thingo. I asked Graham Wallis and he said it should be pretty well 403 carb to go with 403 block so I just put the whole thing on.
    Tomorrow I'll have it going so will know how it runs.
    If , as you say. it sucks oil, I'll revert to a standard 203 type paper filter.
    Shouldn't suck oil just be a bit noisier because of the lack of the silencer.
    Graham

  12. #12
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    Definitley a significant amount of induction noise but the oil disappears after 6 to 800kms of driving and there are no leaks evident so I don't know where it goes. The plugs are relatively clean so it is not enough to foul them and it runs perfectly so I just top it up when I have to and hopefully (to date) before it runs out altogether.
    I have a paper element that fits the oil bath cylinder but am a bit hesitant in putting it in as I am not sure how well it will seal. If it is in over the top of the oil I will have to build some sort of landing so it doesn't sit in the oil but I still believe it will just get clogged with oil due to the induction pressure and the air flow will become servely restricted.

  13. #13
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    I think the point of the paper filter is to use it instead of oil so yes it has to seal properly. If it's too much trouble I'll just put the normal 203 filter on top of the carby. It might run better with that too.

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    Default Rocker cover gasket?

    A thought, where did you get the gasket for the 203 rocker cover? 403 ones are plentiful 203 ones never seem to be listed and if you manage to get one they are cork. Same goes for liner seals, except the cork bit!

  15. #15
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    It's interesting to see that FLASH and Luthier have 203 heads on 403 blocks. Forty years ago I replaced the engine in one of my 203's with a rebuilt 403 engine and was amazed that the increase in capacity of only 160 cc could give such an increase in performance.

    After a while I experienced pangs of guilt because the 403 engine did not look "right" in its new home.

    To make it look original again I fitted 403 valves to the 203 head, changed the jets and choke in the carburettor, and I think, used 403 rocker gear.

    The upshot of this was that it still went well and there was no "seat of the pants" difference in performance.

    Norm

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    Quote Originally Posted by GRAHAM WALLIS View Post
    A thought, where did you get the gasket for the 203 rocker cover? 403 ones are plentiful 203 ones never seem to be listed and if you manage to get one they are cork. Same goes for liner seals, except the cork bit!
    I ordered a set from Der Franzose and yes the rocker gasket is cork. It's two layers laminated on a silver foil. I stuck it to the rocker box with grey silastic, but put none on the head. It seals well there. I ran a layer of the grey round the head previously to cover some porosity, and let it fully dry before assembly. The set was NOS and even had a bit of rust on the exhaust gaskets. I was a bit surprised that it only contained one carby gasket as there should be one for each side of the plate I would think. I used the 403 one I had on top.
    I re-used the rubber rings from under the rocker cover which I had on the 403 setup, but tomorrow when I do the first head tighten I'll put on the ones that came with the set as there is a bit of leakage. When I turned off the engine there were fumes coming out from round the spark plug tubes. Very strange. 403 alloy boxes are so superior.

    But the prognosis is it goes better than it ever has, but is much noisier.
    Are the standard pancake filters quieter?
    I also think I have a fair bit of gearbox noise so will throw some nulon at it in an attempt to prolong changing the box. Just having got it back together I will do anything to drive it for awhile. I also fitted a new rear gearbox mount which helps to lessen dirt road clunks.
    There seems to be a new noise that I think comes from the throttle linkage vibrating on backoff.
    It's orchestral actually.The New 203 Symphony.

  17. #17
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    Quote Originally Posted by 203 View Post
    It's interesting to see that FLASH and Luthier have 203 heads on 403 blocks. Forty years ago I replaced the engine in one of my 203's with a rebuilt 403 engine and was amazed that the increase in capacity of only 160 cc could give such an increase in performance.

    After a while I experienced pangs of guilt because the 403 engine did not look "right" in its new home.

    To make it look original again I fitted 403 valves to the 203 head, changed the jets and choke in the carburettor, and I think, used 403 rocker gear.

    The upshot of this was that it still went well and there was no "seat of the pants" difference in performance.

    Norm
    You got any photos Norm?

  18. #18
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    don't change the oil bath air filter

    it is far better to run and much better/cleaner than the pancake

    hardly any oil, if any will get sucked through

    yes it may be a bit noisier but you will get used to it, it's not like you are running twin DCOE's on it

    enjoy it
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  19. #19
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    Quote Originally Posted by pugrambo View Post
    don't change the oil bath air filter

    it is far better to run and much better/cleaner than the pancake

    hardly any oil, if any will get sucked through

    yes it may be a bit noisier but you will get used to it, it's not like you are running twin DCOE's on it

    enjoy it
    Yes I think it's getting close to needing a whopping great stereo and lots of loud rocknroll.

  20. #20
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    My understanding of the oil bath filters is that they don't draw air thru the oil. The oil is there to dampen the wire filter catching the dust.. A lot of Pommy cars had similar [Vokes type] filters.
    The 203 dry element pancake type filters were for European fitment.
    The wet, oil type were referred to as colonial or tropical filters.

    Flash,
    It's good to see one of Gordon Millers repro "Tecalemit" labels on your filter.

    203,
    "pangs of guilt ?" What is it with 203 owners and 403 engine swaps, only you know and to hell with everyone else.

    Well known, WA former 203 owner/restorer insisted on leaving the original "odd points" distributor on his. What a PTA for adjustment and availability.
    During the resto we ran cabling throughout for fitting flashers. Did he?
    Like heck.

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