[jester]

BBC 477ci with digital 6, crank trigger, msd dist. ,roller cam.
timing is set at 38 degrees but when its reved up around 45K plus the timing advances.
Any suggestions on what can cause this?
Chain is tight. Cam properly end clearanced.

 

[1 bad import]

timing cover is flexing ..when the motor revs the cam is walking i just had the same problem ..

 

[Bear]

Same thing happened on my SBC with crank trigger ect. set at 38 deg, rev it up and it wouldcome up to48 deg. Tried 4 differnt timing lights and they all said the same thing. It ended up that my new MSD 7al-3 was bad right out of the box. Put a new one in and rock solid at 38 deg.

 

[jester]

thanks ill see if I can get a new box to borrow to try it.
i will also check for cover deflection.

 

[Uncle Paul]

With a crank tigger set-up the only other thing I would double check is the Rotor Phasing.
http://www.msdignition.com/pdf/tech%20bulletins/tb_rotor_phasing.pdf