Nothing is ever quite that easy, so Melrose sent a partially welded set, along with some loose pipes for us to test fit and adjust as necessary. Ironically, "Mr. Clean" (Trey Hanson) did most of the "dirty work" of trial fitting and modifying, and then we sent our modified sample back to Melrose so they could make the required adjustments. We subsequently received a production prototype, installed them, and confirmed they fit correctly.
The next challenge was to find the rest of the pieces needed to complete the exhaust system. We want to keep Project C4orce emissions compliant, which means the exhaust system will include catalytic converters. That being the case, we didn't have to think twice before making the next phone call to Random Technology.
We've used Random's converters in just about every other Corvette Fever project (in which emissions compliance was a consideration) and have always had excellent results. Random already offers a stainless-steel, mandrel-bent, 3-inch, dual converter/x pipe system for header-equipped C4s, so building a system for Project C4orce involved making alterations to an existing product, rather than building something completely new. In this case, the task was a bit simpler because the existing system is modular, consisting of an "X-back" portion and separately available front pipes that connect the "X" to various types of headers. Consequently, all we needed to complete the exhaust system was a set of front pipes to fit the Melrose LSx/C4 headers and a pair of mufflers (which are not included in the Random converter/x-pipe assembly).
The C4orce motor mount adapter...
The C4orce motor mount adapter in action. look closely, and you can see the plate aggressively linking block and motor mount. The plates are machined from 31/48-inch-thick steel and bolt to the block using the original LSx mounting holes. "Old-school" motor mounts can then be bolted to the plates, whereupon the engine will fit the chassis as if GM had intended it to. The plate accepts all three motor mount bolts; the lower one can't be seen in this photo because it's behind the frame bracket.
Our original plan was to use...
Our original plan was to use a set of stock LS6 springs and retainers, which, along with the valves, were leftover from a previous project. However, these springs wouldn't accommodate the lift of the C4orce camshaft, so we switched to Comp Cams' 26918 beehive springs and steel retainers.
Vmax's Anthony Spensieri is...
Vmax's Anthony Spensieri is on the attack, finishing up the multi-angle valve job on our 5.3 heads. The capabilities of the Rottler SG8 seat and guide machine have enabled Spensieri to develop a high-precision, repeatable valve seat shape that makes a measurable difference in performance, yet is surprisingly affordable.
According to Random Tech's Clay Ingram, "Our C4 system is a true dual exhaust with an "X" that replaces the single exhaust on '84-'91 models. We figured most people with C4s already had performance mufflers, so the Random system ends at the muffler inlet and that allows you to run just about any muffler you want."
As you might expect, there are a few other components that need to be changed before an LSx engine will drop into a C4 chassis. One is the oil pan. The truck pan (that came with our 5.3-liter engine) is too deep and must be replaced. An F-body oil pan is ideal and reasonably easy to find. We were fortunate enough to find someone who wanted to trade an F-body pan and oil pump pick-up for our truck parts.
While we were at it, we also traded water pumps. The primary differences between the truck and F-body/Corvette water pumps are length and water outlet position. If you're on a tight budget and can't find a suitable replacement, you can make a truck pump work, but it's a lot easier if you install an F-body or Corvette pump