[Mgs] Dynamic timing 74 B

[PaulHunt73]

Consensus?  You must be joking!

You are right to get the ignition right before tackling the carbs, but that 
really relates to fixing any defects causing misfiring which can confuse the 
issue when you are trying to setup the carbs.  A North American 74 (chrome 
bumper) had an 18V 672/673 engine with a 25D4 41491 distributor.  That had a 
static timing of 6 degrees BTDC and a dynamic of 11 degrees at 1500rpm.  So 
if your idle is 1400 to 1500 rpm that's half the job done for you :o)

There can be a number of things that can cause a high idle as well as worn 
throttle spindles and bushings, such as incorrectly set linkages such that 
one butterfly completely closed is holding the other open, a butterfly not 
fully seating in the throat, poppet valves in a butterfly not fully closed, 
insufficient free play in the throttle cable holding the butterflies open, 
as well as incorrectly set idle and fast idle screws.  One thing that 
*can't* cause it despite many claims to the contrary is a vacuum leak.  A 
vacuum leak *will* cause a high idle for a given throttle opening, but an 
engine cannot run on air alone, and you should always be able to stall an 
engine with the idle screws - *if* everything else above is correct - even 
if there is a vacuum leak.

PaulH.

----- Original Message ----- 
>... What is the consensus of what the dynamic timing should be set with 
>vacuum advance disconnected and plugged off??