So you are stuck with intake with dual carbs, dual exhaust, maybe even Barker High Lift rockers (pretty rare to find these days).
I have two sets of Barkers in hand:
Inliners Post circa '04 will part with a set - but I am skeptical of this particular mod (though period correct) - and view them now as a coffee table item suitable for inspiration not necessarily for installation.
First (as others have pointed out in the thread above) they change rocker geometry/ratio but at the same time cant the push rods off perpendicular which may go so far as to cause the rods to rub on the head. But even absent 'rubbing' the canting will likely interfere with the lifter and rod rotating during lift - this will result in adverse wear on the rod, lifter seat and cam lobe.
When I first contemplated these adverse side effects I thought to use the early '37-'39 cup style lifers and the longer push rods to minimize this canting effect - which is consistent with the California Bill speed manual. But when it is all said and done these rockers give you just a modest increase in .050 duration and lift - and only on the intake valves.
But with the stovebolt head design it is really the exhaust port that is holding the engine back. Dual pattern cam grinds that extend the exhaust duration are a better investment:
Inliners Post circa '15 If you are going to the trouble to pull the head and replace the push rods - why not pull the timing gear cover too and invest in a cam regrind, and new lifters as well?
regards,
stock49
