* Transmission crossmember needs to be moved forward from TH400 location (rearward from TH350 or Powerglide). This El Camino had multiple crossmember mounting holes from the factory, already there for different combinations. Even so, we did have to drill and tap two new holes.
* If using a single-pattern flexplate, be sure it matches the bolt pattern on your converter before installing the transmission. Dual-pattern flexplates should not be a problem, though you may consider using one that's SFI approved.
* Proper adjustment of the TV (throttle valve) cable is the most important part of this swap. The TV cable performs the functions of both transmission kickdown and line pressure. Follow the factory instructions to the letter, or call the Hughes Tech Line if you're in doubt. You can fry the transmission in no time at all, if this adjustment isn't done properly. The TV cable resembles those used on a TH350, but the 4L60 cable does a lot more. We can't over emphasize the importance of this step.
* Another key item is properly setting the vacuum modulator. Here again, Hughes supplies easy-to-follow instructions.
* Wiring for the lockup converter is simple: one 12-volt, "key-on" wire to the front, driver's side terminal of the factory plug.
Additional needs:* Three, 1-1/4 X 5/16-inch Grade-8 bolts and locknuts for the torque converter* A 4L60/700R4 dipstick and tube* For aftermarket or Factory shifters, you'll need two metric pan bolts (longer than those supplied with the transmission).
More Numbers To DigestThe Drag Strip Results chart (right) chronicles three runs from late last year with the old TH400 transmission-using both street and BFG Comp T/A Drag Radial tires, and slightly different driving styles. Please note; the best 60-foot time from that outing was 2.02 seconds with a quarter-mile clocking of 13.053 at 106.89 mph. Not too shabby. With his new Hughes Performance 4L60 transmission, Manning ran a 1.89 60-foot time, with a best of 12.82 at 106.90 mph. During his track testing at the end of March, Manning made what most racers would consider "normal" adjustments-tire pressure, length of burnout, and launch rpm.
In conclusion, the net yields include a 60-foot improvement of .34 and a quarter-mile betterment of .225 seconds. Couple that with two days of general driving, which included in-town and freeway (stop and go and just plain go), as well as two demonstration, full-throttle blasts for some clients. At the end of that unofficial fuel test, the consumption came out to 17.8 mpg! Just imagine what constant freeway speeds would yield. We're guessing well over 20 mpg.
Seeing as how most performance-minded folks are of the curious nature, we estimate a swap like this would fall between the $1,500 to $3,000 range, depending on sources, converter selection, accessories, etc. However, please be aware of the fact that your intentions are always best served by dealing with a reputable "high-performance minded" company, for the maximum results and benefits.