<VV> Detonation and overheating

[kevin nash]

>
> The main problem
> is it overheats after about ten or fifteen miles - even on a cool
> Florida day - & I have to wait for it to cool down before I can go
> any
> further. I took the bottom shields off, expecting to find the fins
> all
> clogged with leaves where the storms had blown them in, but they all
> look clear enough. I was thinking of putting a hose pipe down there
> through the fan & see if anything comes out. Or would an air line be
> better?
> And it detonates like crazy - not pinging, but a heavy knock. At
> first
> I thought it was piston slap, but it doesn't do it from cold. It does
> start doing it before the engine gets the slightest bit hot though -
> before it has even reached running temp I would say. I haven't
> checked
> things like ignition timing yet. I'm not quite sure which job to
> tackle
> next, so I thought I'd throw this lot out there to see if anybody has
> any suggestions?
>
  Since this has "suddenly" started happening on your other Corvair, perhaps they have a common cause. A very common cause these days is old gas. Any gas that has been sitting for a year can cause these symptoms, as most of the octane that was in when it was fresh has now evaporated. If you know that the gas in your Corvairs is fresh, it is time to pop the fan shroud off and look for blockages, and make sure that the cylinder baffles are in place and that the cylinder head fins are clear and properly de-flashed.
Next thing to check is the ignition timing, to be sure that it is correct. Too weak of timing will also cause this... often enough someone thinks they can retard the timing enough to run regular, and "sometimes' they can get away with it but LORDY they can run hot that way!! also, check your fan belt... light dragging when trying to turn the alternator when cold, "heavy" dragging when warm.
Kevin Nash
63 Turbo, port fuel injected daily driver
22psi boost!!
most awseome cooling fan on the planet!!