Exhaust system – advice sought

Discussion in 'Engine & Transmission' started by Friedo, Jan 7, 2011.

  1. Friedo

    Friedo Member

    Messages:
    131
    Location:
    Kincumber NSW
    Hi
    I am seeking advice with regards to what would constitute an appropriate exhaust system replacement for my ’69 Lowlight bus.

    The existing system has a number of cracks etc. causing a regular backfire and power loss. Have tried putty and bandages but a sustainable fix is unlikely.

    The engine is a 1600 single carb which is a little tired. My intention is to spend some money on it but not in the immediate future. When I do it will probably be kept relatively standard with perhaps a slight increase in capacity. The heater hoses have been removed and I do not intend to replace these. I realise that it would probably be best to upgrade the engine and exhaust system at the same time but the general performance is in need of improvement nowish. The bus is not currently a daily driver but I am working towards it being able to be used more regularly.

    I have read a number of the KC forum threads on the topic – seems that a stock system for a stock engine is the general consensus. I appreciate from some of the discussions that there is a lot of theory behind getting it right – to be honest most of this is lost on me. What I am after is something that will be immediately functional and that would be able to accommodate an engine upgrade. I understand that an engine retune will be required when a replacement system is introduced.

    Any thoughts on system type, where it would be best obtained, an approximate cost and whether a muffler specialist or generalist mechanic should do the work would also be helpful.

    Thanks in advance,
    Mark
     
  2. SunnyJim

    SunnyJim Well-Known Member

    Messages:
    1,397
    Location:
    carindale Brisbane
    thunderbird

    hi mark

    i bought a thunderbird from mick motors and rohan had good advice for me.

    sunnyjim is a 71 with only a 1600cc engine i wanted to maximise the little power it has. also my son is a 18 yr old p plater didn't want to too loud.
    it was a true 4 into one so balanced . The sound was not loud .

    I installed it ok my self, the only problem I had was that the tail pipe blew straight onto the nicely painted white bumper bar (as I believe this was NOT the factory option).
    So I had to cut it and reweld at a different angle

    paul
     
    Maxa1967 likes this.
  3. Carter

    Carter Member

    Messages:
    750
    Location:
    Mount Gravatt East, Brisbane
    I have the same system as Paul. Highly recommend it. Will lose a little back pressure therefore a tiny about of torque down low. But it's barely noticeable at all. You may need a re jet of your stock carb, but you may not. Dyno tune would be the best bet to check it. But the thunderbird system will work well with slightly increased capacity and dual carbs. Head work will go together with the while package well down the track. think it's good for up to around 90hp.

    All in all for a stock engine it's a decent replacement and for a mild steer engine it's great!

    All in all
     
  4. Friedo

    Friedo Member

    Messages:
    131
    Location:
    Kincumber NSW
    Ta gents

    Any ideas on a price?

    Cheers
     
  5. Carter

    Carter Member

    Messages:
    750
    Location:
    Mount Gravatt East, Brisbane
    around the 200??
     
  6. bagman

    bagman Well-Known Member

    Messages:
    1,220
    Location:
    Hunter valley
    Hi all- so lately it sounds like I have a hole in my exhaust ( 2 ltr FI) you know that familiar sound when you have a hole your exhaust mainly noticeable on acceleration or when driving in narrow streets or over bridges you can hear that distinct different sound . So I have checked the muffler and tail pipe no holes - even put my hands between the heat shroud and muffler ( not try this when its hot ) all good no holes for a muffler that's about 20 years - next Checked the heater boxes all good ( one is newish anyway) . Gasket seals look ok too. May be the baffles are shot within the muffler ? But that but be a rattle - would appreciate any thoughts.
     
    Last edited: Feb 10, 2018
  7. Barry

    Barry Well-Known Member

    Messages:
    2,394
    Location:
    Abbotsford NSW
    if you block the exhaust pipe with a tennis ball (and oven gloves?) you should be able to stall your motor

    If it runs - then you have holes and you will definitely be able to feel where the leak is

    if it was a hole there should be back firing

    I reckon baffles?
     
    bagman likes this.
  8. cbus

    cbus Well-Known Member

    Messages:
    10,663
    Location:
    sunshine coast
    I would suspect flange gaskets.
    Run cold and put fingers around and on top to check.

    Normal head underneath trick and try to pick source.

    Ball as Barry mentioned may help.

    Check exhaust to heads joint.
     
    bagman likes this.
  9. Wayne murray

    Wayne murray Well-Known Member

    Messages:
    1,567
    Location:
    Seven hills
    I check at night time with a touch it shows the black soot where it is leaking.
     
    bagman likes this.
  10. bagman

    bagman Well-Known Member

    Messages:
    1,220
    Location:
    Hunter valley
    Thanks all - got the tennis ball ready, waited till dark - ran it cold and found the little sucker leaking just before the outlet to the tail pipe - and behind a support bracket - so can't see it but can feel it - yes Wayne there is some soot.

    So on the look out for new muffler would prefer German - as once had a Mexican and the Dak dak sound was just not right - so again any recommeded suppliers?

    Funny that when it comes to the sound of a VW not being right no problem - tune a guitar - could never do it even if my life depended on it .
     
    David H likes this.
  11. Barry

    Barry Well-Known Member

    Messages:
    2,394
    Location:
    Abbotsford NSW
    Good find

    Cant get an exhaust shop to weld it up?
     
    bagman likes this.
  12. bagman

    bagman Well-Known Member

    Messages:
    1,220
    Location:
    Hunter valley
    The thought did occur to me - but It's already been done once before in that area - so was going to get it done once and for next 20 years
     
  13. Grantus

    Grantus Well-Known Member

    Messages:
    13,977
    Location:
    Southern ACT
    Had mine welded up a few times......but the last time, he did say it’s getting tough to weld rust....:eek:

    :D
     
  14. cbus

    cbus Well-Known Member

    Messages:
    10,663
    Location:
    sunshine coast
    New quality one dies fix the problem for a long time.

    A spot sandblast and brazing would be easier than trying to mig it.
    Maybe cut off the support bracket, big patch, then reweld bracket.
    Obviously ok if you have the gear but less efficient if paying welding rates.
    Foreigner for the workshop ?

    Sandblast and silicone ?
    Resists temps ok but getting adhesion can be difficult.
     
  15. oldman

    oldman Super Moderator Staff Member

    Messages:
    7,767
    Location:
    Avalon Beach NSW
    For a couple of hundred dollars, get an Ernst. Best stock muffler you’ll find.
    Bus Stop, JK, or most muffler shops can get em in. Fit it carefully and use the copper nuts.....they’ll never seize or rust on.
    Cheers,
    Mark
     
  16. KahunaKombi

    KahunaKombi Super Moderator Staff Member

    Messages:
    17,957
    Location:
    Bracken Ridge, Qld
  17. bagman

    bagman Well-Known Member

    Messages:
    1,220
    Location:
    Hunter valley
    David H likes this.
  18. cbus

    cbus Well-Known Member

    Messages:
    10,663
    Location:
    sunshine coast
    Probably has a dual meaning ? ;)
     
  19. bagman

    bagman Well-Known Member

    Messages:
    1,220
    Location:
    Hunter valley
    Had it inspected today with a view to patch welding .....not possible Baffles gone - guess what I am getting for my birthday
     
  20. cbus

    cbus Well-Known Member

    Messages:
    10,663
    Location:
    sunshine coast
    Baffles gone = sports muffler.
    First thing that got done to old motorbikes :)
     
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