In 2012, Donnie approached me about building the engine for his Dover white 1979 L78 Chevelle SS396. I enthusiastically agreed–naturally.
Here is the foundation for Donnie’s build, a 1969 dated “CE service replacement block.
Upon initial examination at the machine shop, it was noted that sometime during this engine’s previous life that someone had used a ridge reamer on the top of the bores. In experienced hands, this is not a problem. Of course, that wasn’t the case here. While the bores were found to be virgin 4.094″ with minimal taper, the tops of the bores had been reamed so far that the block would not clean up at .030″ over. Luckily, it would just clean up at .040″ over.
In the interest of retaining as much cylinder wall thickness as possible, I discussed the issue with Donnie and we agreed it would be best to try to locate some .040″ pistons as opposed to going straight to .060″ over. This decision presented the first hurdle I had to clear on this build…finding .040″ over pistons!
As some here have found out by now, 396/402 piston selection has dwindled significantly in recent years. The old stand-by SpeedPro/TRW style pistons are still available, but not in .040″ over. Conveniently enough, I had just recently got set up as a dealer for Racetec/Autotec pistons. Problem #1 solved.
The workmanship on these pistons is very nice, and one of the best features about them is the ability to make any of several changes in specifications on any of their available pistons. Bore size, ring placement/specifications, compression distance and dome configurations are all customizable by request.
Donnie noted that he wanted a true 11-1+ compression ratio in this engine. As such, I specified a little extra dome volume since we would not be cutting the deck surfaces on the block (in the interest of retaining the pad info), and the heads were only going down to 108 c.c.’s. We wound up with just a skosh over 11.4-1. This one will be sipping on high test. grin
Next up through the inspection process was the crankshaft. As luck would have it, the crank Donnie originally supplied was toast–cracked in 3 places. Shame too as it was standard/standard and barely even needed polished. frown I managed to source a fresh .010-.010 6223 crank locally, and we were back in business.
Next up were the rings. Since I pretty much never use a “shelf” ring combination any more, I called up Total Seal and had them chef me up a custom set of rings.
Everything else on the bottom end was pretty much straight-forward, so I didn’t bother documenting the lower end assembly. In a nutshell, the block was bored & honed with torque plates, the mains received a much-needed line hone, the crank was measured and the appropriate bearings procured, and voila–one assembled short block.
Since the lifters needed some sort of motivation, Donnie nabbed one of the Bullet 143 blueprint sticks Rob Clary (from the Supercar Registry) had ground up. Keeping the camshaft company is my usual Crane Billet roller timing set.
Now that the short block was wrapped up, it was time to install the heads. These units are a set of dated 840’s which Donnie provided. After the usual machine shop check-up, they were deemed fit for service after receiving a full set of bronze guides, a 3 angle valve job, and a set of Manley 1 piece stainless steel 2.19 1.72 valves. Once the preliminary machine work was done, the chambers were measured and the decks were shaved just enough to bring them to 108 c.c.’s.
As is often the case, somewhere along the line these heads had received a very light amateur port job. In the interest of cleaning this up and picking up a little air flow in the process, I had head guru Dave Layer (RIP) from Heads Up! cylinder heads whip up a mild street/strip port job.
