[Mgs] Dynamic timing 74 B

[Bill Mills]

at what speed does the mechanical advance begin to kick in?

-----Original Message-----
>From: PaulHunt73 <paulhunt73 at virginmedia.com>
>Sent: Jul 4, 2013 11:32 AM
>To: Bill Mills <bmills46 at earthlink.net>, mgs at autox.team.net
>Subject: Re: [Mgs] Dynamic timing 74 B
>
>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??