[TR] The big bang

[Randall]

> I have SU carbs that may be running a bit rich, but I am not sure how to
> quantify.  I have been playing with the idle as it has been fairly high
> (1200 rpms at idle)  

That would be the recipe for unburned fuel igniting in the exhaust after
shutting the engine off.  Most likely it will disappear once you get the
mixture right, the idle down, and enough driving in to burn away the sharp
edges of carbon in the exhaust (that are currently igniting the unburned
fuel).

> I do have 87mm pistons & a 270 cam

That may mean you need to switch to different needles.  There are many
choices available; the 'rich' needles offered by most vendors combined with
setting the idle mixture to the lean side might work well.  Or not.

Also make sure you have the valve lash set to that specified for your cam.
Performance cams generally take more lash; so running them with the stock
lash can increase reversion at idle and cause problems.

-- Randall