Smallblock efficiency or How to have your cake and eat it too

BigBlockMopar said
No real need for overpriced MSD stuff; You can get a programmable ignition box for under $200 ( "Black Box" @ CB-Performance).

CB Performance Black Box Programmable Timing Control Module

The stall convertor currently in the 518-transmission is a late '60s stock 727 unit as found in C-bodies.
A believe 1" larger in diameter than the much newer convertors used in the '90/'00 OD-transmissions, so, besides being heavier, it's probably having more resistance/drag inside too.
I've had a smaller OD+Lockup trans and convertor in the car for a short time once and noticed the engine seemed to rev noticably quicker and wasmuch happier. I'm currently rebuilding that transmission and hope the install it again soon.

PATC offers performance converters with upgraded clutches for lockup. On a street car I would use the lock up type. Only reason not to do so other than lock up converter issues is the hollow input shaft is not quite as strong as the solid non lock up version. I plan to build an A500 lockup to go behind my 340 EQ head build to gain a lower 1st gear, increase in efficiency, and smaller overall case and tail housing. If it were a 360 or stroker I would probably build a lockup 518 due to the torque curve coming in at lower rpm. PATC - Performance Automotive & Transmission Center