TECH | 25 BIG-BLOCK BUILDING TIPS
SNEAKY STROKER
The 440 block will accept a surprisingly large stroke without
the need for any (or, at least, very minor) block-clearance
work. That means you can build big torque and no one will
be the wiser. A stroke of up to 4.125 inches is doable, as long
as the rod journals are the smaller, Chevy-size 2.200 inches.
Don’t stretch the stroke too far, however. Going to 4.250
inches may cause camshaft interference.TOP FUEL TIP
The rear main seal is another common leak source, and the
hands-down best seal for the job is the Fel-Pro Viton rear
main seal #2947. It is the same part used in Top Fuel and
Funny Car racing engines, and if it’s good enough for them...REAR MAIN RETENTION
Along with the seal itself, the factory rear main seal retainer
simply isn’t great at retention. There are a number of after-
market options, mostly made of billet aluminum, including
one from Mother Mopar herself. They’re inexpensive—around
$50–$75 or so—and there’s no reason not to use one when
building your engine. Unless, of course, you enjoy wiping
up oil drips from your garage floor.CLEARANCE, CLARENCE
Checking the clearances during the assembly can’t be
overemphasized, and you don’t need a NASCAR tool
collection to do it. Feeler gauges are preferred, and even tried-
and-true Plastigauge get the job done in a pinch, ensuring
bearing clearances, rod side clearances, and more are within
spec. Get them correct and the engine will run forever.CAMSHAFT QUICKIES
Cook prefers a good-ol’ hydraulic flat-tappet camshaft for
the RB rather than a roller cam. “They just seem to respond
better,” he says. Fair enough. And as this photo shows, he
doesn’t go crazy with the moly lube during insertion. “It’s
really messy, and because the valley is open on these blocks,
you can use only a little lube to slip it inside the block and
coat it with plenty more once it’s installed.”BUY A NEW BUSHING
The intermediate shaft bushing for the oil pump should
always be replaced with a new one. Yes, it’s true the original
can be reused, but years of use and the heat from block clean-
ing during a rebuild can affect it, allowing it to rotate within
the bore—and that’s not good. A new bushing costs only
a few bucks, so don’t cheap out here. Buy a new bushing.36 moparmuscle.com