Reading spark plugs (mixtures)
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  1. #1
    1000+ Posts Dave's Avatar
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    Default Reading spark plugs (mixtures)

    Hey guys,
    I pulled one of my spark plugs out to see how it was surviving. The core and electrodes are light brown and fairly clean, around the round edge near the thread is a little sootie but its only light and wipes off with a finger.
    So i think that means I have the mixtures fairly right? Here is a picture, sorry its a little fuzzy, tell me what you guys think. Its a carburettor car so i dont think i'll get it much better, but suggestions are appreciated. For interest sake its a Bosch super 4 FR78X.



    Dave

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  2. #2
    1000+ Posts alan moore's Avatar
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    Looks to be running fine to me. I like the Bosch Super 4s, and have been using them in the 306.
    '56 Renault 750 (16TS Power)
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  3. #3
    1000+ Posts Dave's Avatar
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    Thanks mate, so its not a big concern having a bit of carbon around the edges?

    Last time I went to buy some plugs they were out of 4 packs of the super 4's so i just bought a 6 pack, so if i get a 6 pack next time i'll have a whole spare set. I wonder if it adds up cheaper in the long run.

    Thanks again for the cam Alan, the car is running really well now that it has some compression and the newer head to complement it.
    I would have said hi at the french car day, but i didn't realise until the end that you were the michelin man
    Not 750 was looking very nice indeed, how is the M3 engined car going?

    Dave
    Last edited by Dave; 12th August 2004 at 10:29 PM.


  4. #4
    1000+ Posts alan moore's Avatar
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    The 2002 is still waiting for about 20hrs of work to be done, mostly wiring and setting up sensors. Trouble is I work 60hrs+ a week, and then on my one day off I will go to a motorsport event or work on one of my bikes. Maybe I am just scared that it won't be as fast as it was going to be when I pulled it off the road six years ago. 280 Hp hardly seems enough when compared to 450+ in a modded Skyline.
    Then I have another project arriving from England mid September. Like I need something else to work on!!!

    Glad to see you are enjoying your Cit, although I think twin DCOE 45 Webers would improve the performance considerably, for a lot less than a quad throttle bodies with programmable injection.
    '56 Renault 750 (16TS Power)
    '62 Renault Dauphine Gordini
    '89 Renault Alpine GTA V6 Turbo
    '08 Renault Megane sedan

  5. #5
    1000+ Posts Dave's Avatar
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    The BMW should be nice once its finished, what toy is arriving in september?

    I would love to put DCOE's on the car at some stage, i would have to work out how to reposition the alternator though.
    Would i definately need 45's? A 36mm choke would be about right i think.

    What is your opinion of Dellorto DHLA's? Are they comparable, better/worse than the same size dcoe's? Do they have easily available parts? The reason i ask is I see them for sale more often than i see DCOES.

    Thanks for your help,

    Dave


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    Budding Architect ???? pugrambo's Avatar
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    what about a pair of DFI webers ?

    they are basically a downdraught version of a sidedraught
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  7. #7
    1000+ Posts Dave's Avatar
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    I know DCOE/DHLA mainfolds are available for the XU engines, however i think if i were to use twin downdrafts i would need a custom manifold??

    In europe there was a Citroen BX Sport which came after the GT but before the 16Valve, it came with twin sidedraft solex's so my easiest solution is either one of those manifolds, or you can get aftermarket versions from a number of places in the uk.


    Dave


  8. #8
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    Quote Originally Posted by Dave
    I know DCOE/DHLA mainfolds are available for the XU engines, however i think if i were to use twin downdrafts i would need a custom manifold??

    In europe there was a Citroen BX Sport which came after the GT but before the 16Valve, it came with twin sidedraft solex's so my easiest solution is either one of those manifolds, or you can get aftermarket versions from a number of places in the uk.


    Dave

    there was plenty of twin carb manifolds released for the 1.6l XU engined 205's as well as the larger ux engines in 405's i believe... straight from the peugeot factory, i'll probably be looking at one of these on my car as well one day
    Last edited by orestes; 13th August 2004 at 01:11 PM.

  9. #9
    1000+ Posts Dave's Avatar
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    The sidedraft manifolds are 129 pounds from pugspares in the UK. I have never heard of twin downdraft manifolds for an XU before. Dont get mixed up with the tu engined 205's they used twin downdrafts sometimes.



    Dave


  10. #10
    1000+ Posts CHRI'S16's Avatar
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    Quote Originally Posted by Dave
    Hey guys,
    I pulled one of my spark plugs out to see how it was surviving. The core and electrodes are light brown and fairly clean, around the round edge near the thread is a little sootie but its only light and wipes off with a finger.
    So i think that means I have the mixtures fairly right? Here is a picture, sorry its a little fuzzy, tell me what you guys think. Its a carburettor car so i dont think i'll get it much better, but suggestions are appreciated. For interest sake its a Bosch super 4 FR78X.


    Dave
    ... a little on the lean side, but good for everyday running. Are all the plugs like this? Cheers.
    Chris
    ... ptui!

  11. #11
    Banned orestes's Avatar
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    Quote Originally Posted by Dave
    The sidedraft manifolds are 129 pounds from pugspares in the UK. I have never heard of twin downdraft manifolds for an XU before. Dont get mixed up with the tu engined 205's they used twin downdrafts sometimes.

    Dave
    hmm time to have a good look at my haynes manual, i may be wrong here. at todays rate 129.00 GBP United Kingdom Pounds = 331.197 AUD Australia Dollars. that doesn't sound to bad, but still before shiping
    Last edited by orestes; 13th August 2004 at 01:30 PM.

  12. #12
    1000+ Posts Dave's Avatar
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    Quote Originally Posted by CHRI'S16
    ... a little on the lean side, but good for everyday running. Are all the plugs like this? Cheers.
    Chris
    Thats good to hear, i'm trying to run it a little lean to stop the head carboning up (and fuel consumption). The way i have the carb set up is that it runs a little lean on the primary throttle, but if i open up the 2nd throttle it is fairly rich and compensates for the leanish primary, so if i flatten it i get ideal mixtures for power, but if i'm cruising or accelerating slowly its a little lean.

    I'll check another plug for you.

    Dave

    EDIT: I just checked the other plugs and they are all in the same condition.
    Last edited by Dave; 13th August 2004 at 01:52 PM.


  13. #13
    1000+ Posts Dave's Avatar
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    There was one 205 that used twin sidedrafts, from memory it was the rallye, this however isn't helpful as it is still the TU series engine.

    Dave


  14. #14
    1000+ Posts CHRI'S16's Avatar
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    Quote Originally Posted by Dave
    Thats good to hear, i'm trying to run it a little lean to stop the head carboning up (and fuel consumption). The way i have the carb set up is that it runs a little lean on the primary throttle, but if i open up the 2nd throttle it is fairly rich and compensates for the leanish primary, so if i flatten it i get ideal mixtures for power, but if i'm cruising or accelerating slowly its a little lean.

    I'll check another plug for you.

    Dave

    EDIT: I just checked the other plugs and they are all in the same condition.
    Well done Dave. Haynes has a book on spark plugs and carby set-up, it used to help me with my earlier days in go-karting. Gap and range is everything, price or "fancy" names has very little to do with it. But you can read alot from your plugs. Having said that on a race kart or even racing car, the plug can only show you what you have done recently, so if your warm down lap was very slow it will show a bit on the rich side.... but how was it in the race... hard to say, but in 2-strokes better to be on the rich side of things.
    Spesh when some egines rev to 23000 [email protected]#@!!
    As a general rule, I run a hot plug in the colder months or colder weather and a colder plug in the summer or heat. That generally works well.-Chris
    ... ptui!

  15. #15
    1000+ Posts Dave's Avatar
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    Quote Originally Posted by CHRI'S16
    Well done Dave. Haynes has a book on spark plugs and carby set-up, it used to help me with my earlier days in go-karting. Gap and range is everything, price or "fancy" names has very little to do with it. But you can read alot from your plugs. Having said that on a race kart or even racing car, the plug can only show you what you have done recently, so if your warm down lap was very slow it will show a bit on the rich side.... but how was it in the race... hard to say, but in 2-strokes better to be on the rich side of things.
    Spesh when some egines rev to 23000 [email protected]#@!!
    As a general rule, I run a hot plug in the colder months or colder weather and a colder plug in the summer or heat. That generally works well.-Chris
    I've got a feeling this plug gets a little too cool when idling in heavy traffic, but its not getting too dirty so i think i'll leave it be now, if it aint broke dont fix it i here them say

    Dave


  16. #16
    1000+ Posts Dave's Avatar
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    Quote Originally Posted by orestes
    hmm time to have a good look at my haynes manual, i may be wrong here. at todays rate 129.00 GBP United Kingdom Pounds = 331.197 AUD Australia Dollars. that doesn't sound to bad, but still before shiping
    Hey mate i looked through my email folders and found my conversations with different places when i was looking at this. Here is the best price i found.
    Dave

    Dear Dave,

    We can supply a Manifold from stock, with Gasket, Studs & 'O' Rings - GBP
    119.50; we can send this by Swiftair (around 5 days) for GBP 19.50.

    Best regards,

    Peter.
    --
    Autofive


  17. #17
    1000+ Posts alan moore's Avatar
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    I think those sidedraft manifolds are made for 45s, although you can still fit 40s on these. I think Dellortos are fine, and there is one place in Bris that sells the jets. I use Webers as I have probably $2000 worth of jets and emusion tubes and such for them. Well set up I don't believe there is any difference in performance.

    Alfa GTVs may be a source of cheap 40 mm Dellortos but only have 30mm veturiis in them from memory, but they can be turned out. 40s are limited to a 34mm venturi, which would work OK on your motor. My old single cam, all out 2L BMW motor had 45s with 38mm chokes and made about 185 clydesdale Hp at 7200. Would run it to 8300 if necessary. These large chokes are only necessary when you are going to rev it hard.

    My new toy is a Renault Alpine GTA V6 Turbo, that I bought in London, but the shipping has been delayed again, meaning I will be lucky to see it by the start of November.
    '56 Renault 750 (16TS Power)
    '62 Renault Dauphine Gordini
    '89 Renault Alpine GTA V6 Turbo
    '08 Renault Megane sedan

  18. #18
    1000+ Posts Dave's Avatar
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    Quote Originally Posted by alan moore
    I think those sidedraft manifolds are made for 45s, although you can still fit 40s on these. I think Dellortos are fine, and there is one place in Bris that sells the jets. I use Webers as I have probably $2000 worth of jets and emusion tubes and such for them. Well set up I don't believe there is any difference in performance.

    Alfa GTVs may be a source of cheap 40 mm Dellortos but only have 30mm veturiis in them from memory, but they can be turned out. 40s are limited to a 34mm venturi, which would work OK on your motor. My old single cam, all out 2L BMW motor had 45s with 38mm chokes and made about 185 clydesdale Hp at 7200. Would run it to 8300 if necessary. These large chokes are only necessary when you are going to rev it hard.

    My new toy is a Renault Alpine GTA V6 Turbo, that I bought in London, but the shipping has been delayed again, meaning I will be lucky to see it by the start of November.
    Awesome, is that the same sort as the red one we saw at the FCD this year?

    I think the maximum i would rev my engine to is 7000rpm. So 45mm carbs with 36mm chokes would be perfect but if i could only get 40's with 34mm chokes it would be nicer to drive daily.
    Anyway i wont be able to tackle this for a while so thanks for your help Alan, maybe in time for the FCD next year

    What would you pay for a pair of 45 webers in unknown condition, say off ebay or the trading post? Also what is a fair price at a wrecker for a pair of 40mm dellortos?

    For anyone else interested in jetting weber or dellorto sidedrafts this is a great program (see attachment)

    Dave
    Attached Files Attached Files
    Last edited by Dave; 16th August 2004 at 11:16 PM.


  19. #19
    1000+ Posts alan moore's Avatar
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    $400-$500 for used pair of 45mm Webers, depending what they come with. eg. ram tubes, air cleaner. 40mm Dellortos around $200 -$300 a pair.

    The GTA is the model before the A610 at the Grand Display. Similar looks, no concealed headlights, slightly smaller dimensions, 250Kg and 50 Hp less.
    '56 Renault 750 (16TS Power)
    '62 Renault Dauphine Gordini
    '89 Renault Alpine GTA V6 Turbo
    '08 Renault Megane sedan

  20. #20
    1000+ Posts alan moore's Avatar
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    There are a pair of 40mm Dellortos with air cleaners, on Ebay.au with 2 days to go at $203 currently. They have come off an Alfa, and stand a fair chance of being not too far off the mark as regards jetting etc for your BX.
    '56 Renault 750 (16TS Power)
    '62 Renault Dauphine Gordini
    '89 Renault Alpine GTA V6 Turbo
    '08 Renault Megane sedan

  21. #21
    Fellow Frogger! AlsPug504's Avatar
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    Default Plug Reading

    I reckon you might wanna sink the boot a bit more when driving. Or get a Auto shop to sample the HCs output though out the rev range it might be a little high!

    Als

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