VINTAGE ENGINE TECH: 392 HEMI

VINTAGE ENGINE TECH

Editor’s Note: This new column is dedicated to providing miscellaneous tidbits of info relative to ever-popular vintage engines that simply refuse to wander off into oblivion. These are the mills that remain dear to our hearts, and that find homes in an array of vehicle applications including nostalgia drags, street rods, old-school hot rods and restored collectors.

WARMED-UP 392 HEMI

This brief article takes a quick peek at a project that started with a resurrected 1957-58 vintage 392 Hemi block during a build by Jody Holtrey of Medina Mountain Motors in Creston, Ohio.

According to Holtrey, this particular customer’s engine will be stuffed into a 1934 Chevy hot rod (that’ll cause a few Hemi guys to cringe), intended for street cruises and local shows. The owner also plans to use an old 1971-vintage Lenco blower, mostly for the eye-candy effect (apparently one of only 10 built).

With bores set at 4.030″ and a 4.500″ stroker crank, the old girl will boast 466 cubes of torque-happy giggles for the owner. The connecting rods are Eagle forged units that were actually numbered for a 440 application, at 6.760″ length.

Holtrey noted that the main webs are a particular weak point with OE 2-bolt main caps and a fairly weak web area. The customer provided an old-school main girdle (the type used back in the day), located via the Internet from a Hemi parts hoarder. This girdle contacts the caps and squeezes down to the pan rail by a couple of thousandths, substantially increasing lower block rigidity.

Because of the girdle’s thick pan rail flanges, the original oil pan was notched to clear the girdle flanges and the pan rails were then welded back into place.
In order to accommodate the extended stroke, Holtrey notched the bottom of the cylinder bores for rod bolt clearance (nothing unusual there). In addition, the oil pump (a 360 pump) was spaced out for counterweight clearance by adding a 0.480″-thick spacer and the pump shaft was extended as well.

Other goodies will include a Milodon cam gear drive and a very tasty shaft-mount roller rocker system from Hot Heads.

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1. The 1957-1958 Chrysler 392 Hemi block features 2-bolt main caps and not a ton of meat in the main webs. Main web failures were not uncommon back in the day when these blocks were used for drag racing. Pictures of the build continue throughout this column.

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2. An old-school fix that still benefits these blocks today is the addition of a steel girdle to provide added strength.

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3. This girdle contacts the caps and is drawn down a couple of thousandths to the pan rails. Notches in the girdle clear the main cap bolts.

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4. The rear oil bypass is plugged to ensure that oil flow always runs through the filter.

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5. This 392 build will use a Mopar 360 engine’s oil pump, spaced out to clear the stroker counterweight. The pump spacer is 0.480″ thick. The drive shaft was extended by the same amount.

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6. This particular build will feature a 4.5″ stroker crank along with Eagle 440 rods with a length of 6.760″, which required notching the cylinder bottoms for rod bolt clearance. Bores were opened up to 4.030″ (+0.030″).

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7. In order to accommodate the main web girdle rails, an original oil pan was modified by cutting out a long relief and re-welding the rail flanges.

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8. Holtrey plans to outfit the Hemi’s heads with this very cool shaft roller rocker system from Hot Heads (its Top Fuel package).

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9. The cam gear drive is a Milodon setup.

Note: If you’re in the midst of a vintage build and you’d like to share your knowledge with our readers, ­contact Mike Mavrigian at (330) 435-6347 or at mike.mavrigian@bobit.com. All we ask is that you provide information relative to any phase of the build and a few photos.

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