Camshaft gone flat

Discussion in 'Mech Tech' started by jim mcglynn, May 13, 2019.

  1. davidoft likes this.
  2. davidoft

    davidoft Sponsor

    It can be separated if no takers on the whole thing :)
     
  3. Ok. Do you know the engine condition, other tha It Runs? Has it been driven, or is it a little unknown?

    1979 Super Viking, 2lt type 4, Automatic
     
  4. For an auto you need the engine to idle slowly and smoothly and to produce good torque at low revs – that’s what a standard cam provides. A Scat C25 has more lift and duration and inevitably it won’t idle quite so smoothly or provide as much torque at very low revs but it will make more torque (and therefore more bhp) at higher revs. And it will idle at circa 850 revs and pull well from just off idle on a 2.0l with twin choke Weber IDF carbs.

    Until Gooders couldn’t make it work with his 2.0l auto with single choke Weber ICT carbs I would have recommended a C25 now I’ll still say it should work, but might not. :)
     
    Last edited: May 15, 2019
    jim mcglynn likes this.
  5. jim mcglynn likes this.
  6. The Web Cam 107i is a hydraulic cam and should be used with hydraulic follows. A little more duration and valve lift compared to a standard cam but it’s very mild and should work well in an auto.

    This is what aircooled.net says - ‘This particular Web Cam grind is basically a Factory Waterboxer Grind, but done in a Type 4 version. It's completely compatible with stock or aftermarket FI, and obviously a grind this mild is compatible with any carburetor system. This is fantastic with Automatic Transmissions too! This is a nice upgrade on stockish engines, it's an outstanding bus cam! HD Springs are required! This cam works best with Compression from 7.75-8.25:1. Power band is from Idle-4000.’
     
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  7. davidoft

    davidoft Sponsor


    not much, starts and runs sweet sounds sweet
     
    jim mcglynn likes this.

  8. Top man!! I am thinking that I will just go with standard Cam. Not after a sports car, got rid of that :) Should I bother looking too hard at alternatives ? such as this webcam? Seems a minefield.
     
  9. If you want a mild cam and hydraulic followers the Web 107i is a good choice and probably better quality than most standard cams. VW might have chosen it if they were still making the air-cooled engine.
     
    Patrick Nguyen and jim mcglynn like this.
  10. Thanks Geoff. Interestingly, my mechanic isn't a fan of hydraulic. Are you? Apparently my engine was converted to solid at some point in its long life too....as it turns out.
     
    Last edited: May 15, 2019
  11. Going to go down the rebuild route now. Thanks anyway.
     
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  12. davidoft

    davidoft Sponsor


    No worries
     
  13. Leave it with solid Jim, hydraulic cams wear even quicker than solid and the followers bleed down quickly and take ages to pump back up again.
     
    jim mcglynn likes this.
  14. Nice one, thanks Geoff.
     
  15. How is this going?
    Did the cam come out and is it flat?
     
  16. Booked in at end of July.

    1979 Super Viking, 2lt type 4, Automatic
     
    Borninabug likes this.
  17. I had to rebuild mine last year because the cam was flat. Initial symptoms were it could only do 55mph and less than 20mpg, then the exhaust cam was so flat it would massively pop exhaust back through the carb blowing the fuel and air back through the top of the carbs for cylinders 1 and 3 whenever id go full throttle at more than few thousand revs - weber idf carbs helped diagnose it with one carb barrel per cylinder as it was only the rear two cylinders which share the cam. I never noticed anything in oil, but it never went fast as long as I’ve had it, so may have been through the worse of the wear before my ownership.

    I tried to measure how much the valves moved with engine in which was tricky, but with it out it was really obvious how little the valves moved - exhaust for cylinder 1 and 3 was only 2.4mm with biggest movement at 6.6mm. Now they move more than a cm, and a smarter guy might have wrote it down how much for future reference - but I don’t think I have!

    I rebuilt is as a 2065cc with a scat c25 cam and solid followers shipped from the states and removed gaskets under barrels to raise compression a bit. It is proper fast now and easily does more than 80mph, but now the oil light flickers at idle after it gets hot and still doesn’t do much more than 20mpg - but at twice the speed. I’m investigating oil pressure and temperatures with new gauges before decided whether to be worried... I also need to sort suspension out as it is a lot easier to get out of shape now even in the dry!o_O It idles fine and pulls well from low down the revs. It’s got weber idf36 carbs with amc heads with not particularly big valves. I got a wideband lambda and carbs are running a bit rich, so it may go even better once I’ve played with jetting.
     
    Last edited: Jun 13, 2019
    jim mcglynn likes this.
  18. Valve lift with a C25 is 10.9mm with standard 1.3:1 rockers.;)
     
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