Hemi Engine - Early Hemi Spotter’s Guide Fire Power Vs. Fire Dome Vs. Red Ram By Steve Magnante Photography by Steve Magnante From: http://www.hotrod.com/techarticles/types_of_hemi_engines/index.html It’s been 50 years since Chrysler introduced American motorists to the wonders of the m***-produced hemispherical combustion chamber. What many people don’t realize is that there were three distinct engine families of what’s generically known as the “early Hemi,” each with its own internal and external dimensions: the huge Chrysler Fire Power, the downsized DeSoto Fire Dome, and the even more compact Dodge Red Ram and Super Red Ram. Even though they share prominent design characteristics and look very similar, very few parts are interchangeable and they are all totally different than the ’64-’71 426 Hemi. Here’s an easy way to spot the difference: While the 426s have a front-mounted distributor, all the early Hemis have the sparker in the rear. If you’re looking for the biggest early Hemi power, stick with the Chryslers because speed parts, new and used, are plentiful. The “baby Hemis” from Dodge and especially DeSoto are more difficult because bolt-on aftermarket hop-up goodies are not as bountiful, but this lack of popularity makes baby Hemi core motors far less expensive. Though you can ***emble any early Hemi from loose parts, smart money buys a complete long-block so all of the necessary parts are there for rebuilding. To help make sense of it all, we visited Reath Automotive and quizzed Bob Walker at Hot Heads Research. Check out our findings in the sidebars below.
The identification stamping for all early Hemis is located on the machined pad at the front of the block (arrow).
Heres a trio of Chrysler Fire Power heads. The 331 head (bottom) is identified by its smooth ends, while the 354 (center) and 392 heads have openings for the coolant transfer manifold.
The 392 Chrysler, introduced in 57, has a deck height 1/2 inch taller than the 331 and 354. The 392 intake ports are also lowered with a slight negative impact on port flow. Chrysler 354 (and 331) heads can be identified by a 3/8-inch gap between the deck surface and the bottom of intake-port flange, while 392s are nearly flush with deck. Use of better-breathing 331 or 354 heads on a 392 block requires manifold-to-head spacers and a 392 intake manifold.
The fingers point to rare adjustable (bottom) and much more common non-adjustable rocker arms. Non-adjustable rockers can be used with solid cams with aftermarket adjustable pushrods.
The tall-deck 392 block is identified by 11/16-inch distance between the coolant transfer holes and the deck. The low-deck 331 and 354 Chryslers measure 9/16 inch.
Shown here are the five major Chrysler O.E. varieties. The industrial and marine covers have bumps between the sparkplug tube holes to clear the exhaust rocker adjusters, as do covers originally installed on 300 models. Rocker covers do not interchange between Chrysler, DeSoto, and Dodge Hemi families.
Hemi cranks of every size are high-quality forgings. The eight-hole flange is standard, but holes should be tapped so nuts can be eliminated.
If you s****e together your motor from various sources, be ready for lots of little surprises like inconsistent timing tab placement on this 55-58 front cover (51-54 front covers are cast iron and include the water pump). Its nothing that a competent mechanic couldnt surmount, but its all the more reason to search out an unmolested core.
A cl***ic blunder is to mix Chrysler rocker-shaft stands during ***embly. The stand in the B location is drilled to provide pressurized oil from the head to the rocker arms. It is easy to accidentally switch it with the stand in the D location with dry, squeaky results. This caution also applies to DeSoto and Dodge Hemis.
Intake manifold selection for the Chrysler is wide open, less so for the Dodge, and about zero for the DeSoto. The modern polished aluminum dual-quad manifold (center) is from Hot Heads while repop retro castings are still made by Offenhauser and Weiand.
I saw this tonight, and for good or bad, decided to present this here to share with all of you. Let the debate begin. ~Jason
The Jalopy Journal
