Oldsmobile V-8 Engines. Bill Trovato
move because they are keyed vertically and bolted. This is an extremely high-quality unit, and in my opinion is the most desirable.
The bad news is there were only a few made and no more will be made unless enough orders are taken for a higher production run. Keep in mind that the pan-rail girdles are considered the strongest of the breed, but require oil-pan modifications. Aluminum oil pans made by Moroso are available for the BTR Performance, Product Engineering, Jeff Smith, and Mondello girdles through me at BTR Performance.
The finished BTR engine-block girdle is one of the few Oldsmobile girdles that are often kept in stock. This style of girdle is a proven piece, and I have seen it help hold together engines making about 900 hp on big-block Oldsmobile engines.
In general, it is best to use the 1968–1976 Olds blocks for most high-performance applications up to about 650 hp. If your engine-project goal is above that level, choose a gasoline block with an aftermarket girdle or use a 350 D or DX block with a four-bolt main-bearing-cap conversion for your high-performance project. You could try to find a suitable NASCAR block. They are out there if you are willing to pay the high price for them.
BTR girdle bolts are torqued to the pan rails with 3/8-inch Grade-8 bolts. This ties the pan rail to the main caps and replaces the lack of sufficient thickness in the main webbing. It also ties together the three center caps and studs.
CRANKSHAFTS
The crankshaft transfers all the power made in the combustion chamber to the transmission. In high-performance applications, it needs to be incredibly strong. This chapter will be your guide to the best-possible crankshaft choices for your particular engine build.
Factory Small-Block Crank Identification and Application
All 330-ci Olds engines (1964–1967 model years) were produced with a forged-steel crank. The 350-ci Olds engines produced from 1968 to 1972 were fitted with a nodular-iron crankshaft. Those 350s made from 1973 through 1975 could be either nodular or gray iron, and then gray iron material in all of the 1976 and later engines. All of the small-block 350 Oldsmobile cranks had a 3.385-inch stroke with 2.125-inch-diameter rod journals and 2.500-inch main journals, with the exception of the 350 diesel engines. These had a 3-inch main-journal diameter and were made of nodular iron.
The 330-ci crankshafts are easily recognized by their smooth surfaces, rounded counterweight noses, and wide parting lines on the forging. Use of this crankshaft requires a 330/400/425 flexplate/flywheel because the 1964–1967 small-block flange bolt pattern is different than the 1968-and-later Oldsmobile bolt pattern. Cast-iron 350-ci cranks are easily recognized by their somewhat rougher surface, squared-off edges on the counterweights, and narrow parting lines. The nodular-iron crankshafts are readily identified by a large “N” or “NA” designation cast into the number-1 counterweight.
These three versions are all dimensionally and functionally interchangeable. Although the steel crank is desirable for roughly 600- to 800-hp small-block engines, the nodular-iron crankshafts are very durable in the range of build that the gas 350 block will tolerate. The 350 Olds main bearing webs in the block will likely fail before your 350 nodular crank. The nodular-iron cranks support about 600 peak horsepower. The gray-iron cranks are well suited for stock and moderate performance builds up to about the 400-hp level.
Factory Big-Block Crank Identification and Application
The 1964–1967 “short-stroke” 400-ci engines were produced with forged-steel cranks and are the same as their 425-ci brothers. Later-model (1968–1969) “long-stroke” 400-ci engines could have either cast nodular-iron or forged-steel crankshafts. Most of the big 455 Olds engines produced from 1968 to 1972 were equipped with a nodular-iron crankshaft, but a forged-steel unit can be found. There is wide speculation on exactly where these forged crankshafts were used, but ultimately, there seems to be no specific application where you can be sure to find one, and they’re very difficult to find.
The thin parting lines on the ends of the throws indicate 350 nodular-iron crankshafts.
Notice the undercuts in the ends of the rod and main journals on this 350 N crankshaft. At a quick glance, even with no micrometer, you can tell if the shafts have been ground undersize.
The 330 Olds crankshafts were all steel with the 3.385 stroke. They always have the wide parting lines at the ends of the rod journals and have a smooth finish compared to cast-iron crankshafts.
This part number, 388776, identifies a 330 Olds steel crankshaft.
The older 400 short-stroke and all 425 Olds cranks were steel and appeared very smooth (shown). You can verify that it is a 400/425 versus a steel 455 crank by the lack of a lightening hole in the side of the rod journal.
As with small-block cranks, steel big-block cranks have a smooth look, a wide parting line, and rounded crank-throw noses. The cast 455 cranks have narrow parting lines and squared crank-throw noses. The 455 steel crankshaft is extremely heavy. The weight possibly negates any material advantage there may be over a nodular-iron unit in applications less than 600 hp.
The 400/425 needs the counterweights cut down about .300 inch (shown) to fit in a DX block. You only want to cut as much as you need to fit in the block to avoid having to add expensive Mallory metal.
Depending on the bobweight of the rotating assembly, you need to install Mallory slugs in the counterweights. Expect to pay about $25 to $30 per slug plus the cost of installation. A balance job can be pretty pricey.
The 1973–1974 455 crankshafts could be either nodular iron or gray iron, and they were made exclusively of gray iron material until the end of the original 455 production run in 1977. As with the small-block crankshafts, the nodular-iron 455 cranks are identified by a large “N,” “NA,” or a small “CN” cast into the number-1 counterweight. You may notice that “CN” crankshafts have four lightening holes in the rod journals rather than two holes in the front and rear rod throw as on “N” cranks. Most of these are also machined for pilot bushing installation. The more of these I see, the more I think that they are the nicest of the Oldsmobile 455 cast crankshafts.