46 Jp jpmagazine.com OCTOBER 2019
DON’T DITCH THAT AMC V-8
An Awesome AMC V-8 Recipe
Looking to build yourself an awesome AMC for your Jeep? We asked some of the most
knowledgeable guys we know for tips and combined that with our own engine-building
experience. This won’t be the one that will make the most horsepower on the track, but
it’s the one that will endure grueling conditions and make great power at the same time. In
other words, we’re not sacrificing strength or longevity for horsepower with this recipe.
Block: It has to be the 401 block or an SR (service replacement block). Both are thicker around
the mains and can be modified to a four-bolt main. The 304 and 360 blocks are fine, but if you’re
looking for the best, go with the 401. Don’t bore more than 0.060 over.
Connecting Rods: If you’re not using stock
401 rods, a Chevy rod might be an option for
your custom build. Some machine down the
rod journal to use a Chevy rod.Pistons: KB Pistons has a decently priced
hypereutectic piston for the AMC. Your block
should be okay with 0.060 over (added bore) if
you need to go that much.Camshaft: Don’t get too crazy with the lobes.
A little lope sounds good, but you don’t want
too much of that while you’re rockcrawling.
Get the right grind for your application. Comp
Cams has a nice option that we’ve tried. A
roller cam is a better choice, but it’s a more
expensive option.Heads: Don’t mess too much with a good
thing. The original dogleg heads were hard
to beat. Maybe give them a polish. Factory
AMC heads can be modified to put in Chevy
valves. If you insist on new heads, there are
a couple aluminum aftermarket options that
will drop weight off the total package.
Crankshaft: If you’ve got a forged 401
crankshaft, don’t do a thing. If you’ve got
one from a 304 or 360, you should probably
still do nothing; these are externally
balanced cr anks and will be fine for any
decent 450 hp build. If you’re going to get
crazy, there are aftermarket steel options.