Welcome to CPGNation.com! Log in or Sign up to interact with the CPGNation community.

Dual Sync install with MSD on 427W - How to Fire MSD?

Discussion in 'FAST Support Forum' started by DucatiThunder, Oct 20, 2017.

  1. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    This cam will easily allow an initial idle timing setting of 24 degrees - I wouldn't go lower than that. This affects the idle vacuum, and you need at least this much idle timing to pull vacuum upward. A steady vacuum gauge needle will confirm how much more initial timing you can use. My 406 Chevy has a similar XR282HR duration cam (9.5:1 compression) and likes as much as 28-30 degrees, but I keep it set to 24 degrees to prevent any part throttle ping (idle vacuum begins to drop below 22 degrees - automatic trans, 2500 stall). The lobe separation should have been higher (112-114 for better idle vacuum), but the Sportsman is unaffected by lower vacuum. This cam should also run well for your compression, regardless of the idle vacuum.

    I have my 406 Chevy running 7 degrees of vacuum timing @45%. This should also work for your engine. Of course, all these are ballpark numbers, but should be close enough to start out with. Just make small changes and keep an eye on the sparkplugs. Timing will affect the side electrode heat line - which should be centered in or close to the bend. With A/F, the ceramic should have an even light tan color deeper and at the outer portion half - with possibly a lighter .020 ring at the very end of the inner ceramic (firing tip) due to the MSD cleaning action.
     
  2. DucatiThunder

    DucatiThunder New Member

    Joined:
    Jul 12, 2016
    Thanks! I think the 110 LS was kept to keep the idle lump. It is still a cobra and I wanted to retain that stumble. Brent took that into consideration when he spec'd out the cam by tweaking the lift etc. Ill have a full day tmrw to play around with the timing and prob have to reset the stacks again. I have some more reading up to do on populating the timing table, but you got me off to a great start!
     
  3. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    You're welcome. Here's the cam I actually use in my Boss 351 Cleveland engine - COMP 32-651-8 304HR. That engine is still carbureted, but a Sportsman is on the burner once I get started on it again. NASCAR four speed, 4.56 gearing - my first drag car for the 1971 season.
     

Share This Page