Mack E6 two valve

Hi Paul

The R600 did not have any engine brake on this its second motor. First motor was an E6 350 4v valve with factory Jacobs (blown up by original owner), the second owner put in its current motor, an American import E6 2v 300. I purchased second hand rocker shaft and assembly and had them resurfaced, the Jacobs is a 675 model that bolted on nicely.

I have a FIR700 with a 320 coolpower and factory dynatard. Traveling empty or bobtail it works about 10-15% of the Jacobs. When loaded it will at best hold the engine revs, but sadly will not slow you at all!

I read on the net that piggy backing an exhaust brake to the dynatard is effective, but I have not tried this or know anyone local that has ???