stiffen the block. Some of these girdle manufacturers made them at one time and do not make them anymore, some have them in stock, and some are made only to order.
These girdles all have a slightly different design. These main girdles have been available through such companies as Mondello Performance, Product Engineering, J&S Machine, Rocket Racing, Product Engineering, Dick Miller Racing, Jeff Smith Racing, and Noel Engineering. The goal of these girdles is to reduce block flex and keep the oil-pan rails from spreading due to the thin main webs.
The first type of girdle, the “halo” girdle, is available through both Dick Miller Racing and J&S Machine and bolts onto the block with very little (if any) modifications to block or oil pan, unlike the so-called pan rail-type girdles. It bolts on top of the numbers-1 to -4 main caps and ties them together. Most 403-ci-engine enthusiasts use this style of girdle for ease of installation and cost. I have seen many 403 engines destroyed due to block breakage, but fewer if the halo girdle had been installed on them. I consider this modification cheap insurance for these engines.
To determine if an engine block has siamesed cylinders, look through the freeze plug holes to see if the cylinders are connected. A standard non-siamesed block has a space between the cylinders to allow coolant to pass through.
The Program Engineering girdle (shown) uses steel inner caps, but my preference is the stock caps with a billet girdle surrounding the three main caps and tying everything together.
The Noel Engineering girdle is the strongest girdle made for an Oldsmobile engine. Notice the keyed main caps. Once this whole thing is bolted together, the block and the caps cannot move in any direction. The quality of these girdles is impeccable. Quite a bit of time is involved in making them and they are not cheap, but if you want the best, this is it.
The Noel Engineering girdle has cross-bolted mains, and the 3/4-inch-thick girdle pan rails are torqued to the engine-block pan rails with a nut and stud in every bolt hole. These are the strongest of all the girdles, but unfortunately, there were only a few made, due to the expense in small-run manufacturing.
Jeff Smith made only a few girdles, but the design worked well and is a proven piece.
This is the beginning stage of the BTR one-piece billet engine-block girdle. It starts out as a 150-pound piece of steel; when finished it weighs a mere 18 pounds.
The second category of block girdle is a one-piece unit, either manufactured from a single piece of billet or a series of welded-together parts to make it a one-piece unit. This girdle bolts to the oil pan rails of the block and the girdle material ties the two rails together by crossing over the main caps and tying everything together. Many 800- to 900-hp Olds engines have successfully used this style of girdle. These have been made through Jeff Smith Racing, BTR Performance, Rocket Racing, and Mondello Performance.
The third category of girdle is a bolt-together design that is available through Product Engineering and sometimes available through Noel Engineering. The Product Engineering girdle kit comes supplied with steel main caps for numbers-1 to -4, pan rails, and fasteners. The pan rails bolt in place and bolt into the -1 to -4 main caps through the side. The girdle sold by Noel Engineering is a little more sophisticated. It is installed in the same manner, but the supplied main caps are tightly keyed and bolted to the pan rail sections. I think this is the strongest unit made. The main caps cannot walk or 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”
