Running and Racing Reliably Part II: Continuing At The Bottom

If you perused Part I in the June 2002 issue then you know its premise. For those who missed it, a brief review. While many engine buildups provide power numbers and illustrate the parts used to create them, this buildup of a 455 HO street engine will provide all that plus detail the procedures used to assemble the engine more easily and, most importantly, more reliably. Since we're getting into detail, it will require more pages to cover the assembly process than is usual. Once done, however, you'll have learned a few tricks, provided by noted engine builder Jim Taylor. This knowledge will aid you in any future engine building endeavor, regardless of the intended horsepower goal.

In the last issue, we made mention of the fact that Pontiac hobbyist Thom Greenwald was considering a fuel injection setup for this street engine but, as of this printing, Taylor will ultimately outfit the HO with a carburetor and recommendations will be provided for jetting. As promised, a complete engine buildup worksheet is provided in this installment so that all of the components needed to copy the 455 HO can be referenced easily.

Remember that this is a spirited street engine for cruising and brisk back road performance. It's not a racer, though the assembly procedures carry across the line between the two, hence the name of the story. Let's get back to the photos where we left off with the crank, rods and pistons, so that we can see how Jim Taylor and his apprentice Mark Erney bolt this thing together at Jim Taylor Engine Service.

Here are our TRW pistons installed, viewed from the top side. The block to head mating surface of this block was not decked because it was true, according Taylor. Performing the procedure would have wasted metal and money unnecessarily. We'll explain the numbers on the deck later.	A lower dipstick tube and the windage tray are test fitted next. The lower tube is inserted into the through-the-block tube and the tray is installed with the tube passing through it. The lower tube is marked for depth and removed to check to make sure that it slides into the through-the-block tube far enough. About one inch is acceptable. Rarely will the windage tray just drop into place. More times than not, the tray will not line up with the bolt holes in the main caps to secure it because of misalignment of the tube. Many builders will put pressure on the tray to line up the holes and just bolt it down. The tension on the tray when installed is one of the main reasons that so many trays crack. So Jim uses a chrome-moly pushrod as a tool to maneuver the lower tube into the proper position.	Then the tray is installed again. The process is repeated until the tray mounts perfectly over the four bolt holes with no tension on it. The tray usually cracks right where the tube goes through. Note that we are using a 455 tray. There is a "5" barely visible on the top in this photo. The engine should be rotated after the tray is installed to ensure that there's no interference. The bolts get Loctite.
Some builders will tack weld the lower tube to the through-the-block tube to ensure it doesn't fall out during operation. Taylor prefers to stake the tubes. "Welding is little extreme when staking does the job," he told us.	There is some custom work done to fit the pan for a leak-free seal at the rear. Here, Jim's apprentice builder Mark Erney marks the rear main cap through the slots in the pan to determine proper positioning of the cork seal.	This engine will use a two-slot one-hole oil pan, which would normally require a rubber gasket, because that's the design the aftermarket has adopted. The other two styles (see Panning for a Good Seal before continuing) have gotten very scarce. A smooth rear main cap is also used. However, Jim will still employ a cork gasket because he feels that it seals better than rubber. The seal is installed dead center of the pan rail on the cap, a position provided by the earlier measurement. Permatex Silicone Adhesive Sealant (clear) is built up on either side of the cork to create dams to retain it. According to Jim, "It looks ugly but it works very well!" This setup is left to cure overnight.
While the rear pan seal cures we will turn our attention to the 224-113R Sealed Power oil pump that will provide the needed pressure and volume to feed the 455 HO. The pump is completely disassembled to double-check its components. Shown (from left to right) are a feeler gauge to check clearance between the gears and the pump cover, the gears, a check-ball, the plug to retain the check-ball and relief spring, the extra-thick pump cover to ward off flex, the cover retaining screws and the relief spring.	It's important to examine the check-ball seat (inside the upper hole) to ensure that it's machined concentric and its width is constant. The check-ball seat is machined in after casting. If core shift is severe or a material void exists during casting, it will effect the seat. This is very rare but it does happen, according to Jim. A telltale sign is low oil pressure at idle due to oil leaking past the check-ball and seat but normal pressure at higher rpm since the check ball is off the seat at this point. Here you can see that the casting process did in fact encroach on the check ball seat but the amount is not enough to cause concern in this street engine. This pump will be fine to use.
Though this is a Sealed Power pump, Jim prefers a Melling pickup in street engines. The Melling piece on the left has a finer mesh screen that will filter finer particles in this street engine. Conversely, the Sealed Power pickup (above) has larger openings in the screen, better for racing because there's less pumping restriction than with the Melling unit.		Mark taps the pickup to press its tube into the pump and align the screen with the notch in the pump body. This installation tool is homemade and designed to press in the pickup without damaging the tube.
The pump was installed with the bolts finger tight in the block because the factory bolt shoulders are not wide enough for interference fit through the pump body. Using this to his advantage, Jim positions the pump to provide a straight shot from the gear rotor in the pump to the bottom of the distributor. The bolts are tightened to 30 lbs.-ft. With the pump installed, you can see the Nunzi pump drive. Note that the collar completely surrounds the tang on the pump unlike the factory piece and other aftermarket replacements. Also, the Nunzi piece is made from better materials than typical replacement drives.	Here is the completed bottom end prior to mounting the oil pan.	To determine whether the screen is positioned with the correct distance from the floor of the oil pan, a measurement is taken using a straight edge across the pickup from both sides of the pan rail. The two measurements are averaged and equal seven inches.
The pan depth in the pickup area is measured from the pan rail to the pan floor resulting in 7.25 inches. So the clearance between the screen of the pickup and the bottom of the pan is .25-inch--just what it should be. But the pan can't be installed yet. To find out why, stay tuned for the next issue when we wrap this motor up.	Panning for a Good Seal Pontiac V8 rear oil pan sealing systems were changed a few times between 1955 and 1981. This sidebar illustrates the difference between the types of rear pan seals and the two different rear main caps that accepted them.--TD The earliest is this pan, which features no holes and has a stamped lip to retain a cork seal. Taylor considers this the best design.	A rear main cap like this one, that has a groove to hold the cork seal in place, was employed with the early style oil pan.
The next design, that debuted in about 1974, has a flat surface with no stamped lip but has two slots and a hole to retain a single lipped rubber gasket, as shown. This is considered the worst design by Taylor because the gasket can easily push out due to the fact that the retaining tabs on it are so far apart. The result is leaks.	Pontiac must have concurred with Taylor's findings since this design came later from mid '70s to date. It has 5 slots to retain a double-lipped rubber gasket and greatly reduces the gasket's tendency to push out (when clamped) and leak.	Both of the rubber gasket-type pans are used with a rear main cap that has no provision for the old cork

Both of the rubber gasket-type pans are used with a rear main cap that has no provision for the old cork gasket.