[DeTomaso] 351C (ignition) timing

[Dave Londry]

Not a problem with MSD billet distributors, Art.
No vacuum connection and no vacuum advance, so we couldn't add anything 
anyway.
Just weights, spring and an advance-limit bushing.
dave

Art Stephens wrote:
>      It sounds like we sacrifice performance by running vacuum advance?  I 
> would imagine we have no vacuum advance at WOT?  If that is the case,  let's 
> say we subtract 8 degrees of vacuum advance from the 36 total,  leaving us 
> with 28 at WOT.  So if we make max HP or torque at 36 degrees,  it seems we 
> would be best off if we did not use vacuum advance,  and had a total of 36 
> from initial and centrifugal only?  Or,  is there a problem with running 36 
> degrees of initial and centrifugal,  and then running vacuum advance in 
> addition to the 36?  Can we safely get away with running 44 or 46 degrees at 
> part throttle cruise?
>
> Art
>
>
>
> ----- Original Message ----- 
> From: <JDeRyke at aol.com>
> To: <davel at emspace.com>; <detomaso at realbig.com>
> Sent: Sunday, April 12, 2009 12:25 PM
> Subject: Re: [DeTomaso] 351C (ignition) timing
>
>
>   
>> IMHO you're on the right track: for best acceleration, try to get the
>> centrifugal advance all-in by 3000, with not more than 36 degrees total: 
>> initial
>> plus centrifugal plus vacuum (if used). The exact amount will vary with 
>> the
>> engine setup. Total initial advance is easily varied by moving the
>> distributor body but be very sure the primary mark on your harmonic 
>> balancer hasn't
>> shifted so its still true TDC. The springs only vary the rate of advance, 
>> not
>> the amount, but total centrifugal advance is usually variable by means of 
>> a
>> pin that sticks thu the fixed plate in the distributor and has a sleeve
>> that can be varied in thickness. Total vacuum advance is often variable by
>> sticking a small allen wrench thru the hose connection pipe and adjusting 
>> a
>> bleed hole. Vacuum advance sometimes can
>> increase mileage at cruise but seldom WOT power. Finally, be aware that
>> electronic timing lights vary (especially the dial-back types), so amounts 
>> of
>> all three advances that work fine on your engine-with your light, may not
>> work exactly the same for someone else. And I added to your post-title, 
>> 'cause
>> timing the camshaft is a whole 'nother subject which can affect best
>> ignition timing, too. Good luck- J Deryke
>>
>>