Running and Racing Reliably Part III: Final Installment: Top-end Assembly

To ensure that proper clamping force will be applied to the head after torquing the head bolts, all the bolts are measured to make sure that they're not too long, which would cause them to bottom-out in the block. To do this, Taylor screws each bolt into the block without the head in place, but with the washer that will be used on the head bolt as provided by ARP. Once the head bolt is hand tight, it's backed out one-half turn. Then the distance from the block deck to the underside of the washer as it is pressed against the underside of the bolt head is determined with the calipers. This distance must be less than the distance through the bolt hole in the head, which was measured for the respective position in the previous photo to ensure proper clamping. Those numbers written on the deck, mentioned in the last installment, are the head bolt measurements at each bolt location and the difference between it and the respective bolt hole length in the head.

Once the measurements are completed and it's concluded that the bolts are the proper lengths, the heads are installed with a Fel-Pro 8518 gasket under each. Mark Erney then installs the center head bolt (not the one shown here) dry and torques it to 35 lbs.-ft. What this does is ensure that when the other head bolts are installed with the threads treated to moly lube, the lube will creep up the bolt hole as the bolt is tightened instead of across the deck surface, which could affect the sealing of the gasket. The other head bolts are installed with moly lube and torqued to the 35 lbs.-ft. to set them in the proper tightening sequence.

Then the center bolt is removed, the threads are moly lubed and it is reinstalled and torqued to spec like the others in the proper sequence in two pulls, first to 50 and then 85 lbs.-ft.

Here's why Taylor couldn't install the oil pan before the heads were bolted on. Since this application will have A/C, there is a longer extension on the dipstick tube so it's easily reached with the A/C compressor in place in the Pontiac. The extension attaches to the intake manifold via a bracket. This system is assembled with the intake during pre-assembly to determine if adjustments are needed to the through-the-block tube or the junction of the through-the-block-tube and the upper dipstick tube extension. There's no way to determine if the dipstick extends into the pan to the proper depth unless it's measured in place with the pan off. Jim also wants to set the oil level so that the crank doesn't run through the reservoir of oil in the pan during operation, which could reduce horsepower by 10.

First the engine is leveled, as shown. With a large construction level placed across the pan rails, the engine is twisted on the stand until the bubble centers.

Then the level is laid across the bottom of the windage tray. Since the tray is not a flat surface, Jim will hold the level and adjust until the bubble is centered. Here you can see where the oil level would need to be to keep the crank counterweights out of the oil reservoir (using a stock pan, this level is obtained by running a 1/2 quart less oil than the factory recommendation). Note that the bottom of the level is not at the full mark on the dipstick but about 2/3 of a quart low. Had this not been checked, the owner would always add oil to the Full mark unnecessarily and would lose horsepower in the process. Taylor will make a new mark on the dipstick to register Full for performance use.

With the pan bolted down, Jim and Mark move to the camshaft installation. A timing gear is used as a handle as Mark navigates the 30-weight racing oil lubed cam journals through the fresh bearings, making sure not to nick a lobe, bearing or journal in the process. The Crane hydraulic stick specs out at 228°/228° duration at .050 with .485/.485 lift. Its lobe separation angle is 112° and it's installed at 110°.

Once installed, the cam is turned again by hand, taking care that the journal's centered in the cam bearings, to make sure that it moves smoothly. Then the timing gear is removed and the hardened retaining plate is installed with serrated-under-the-head bolts that Taylor torqued to 15 lbs.-ft. Here you can also see where screw-in plugs replaced the press in jobs used on stock engines, to ward off oil leaks.

The Rollmaster, double-roller, .250 seamless timing chain is installed next. Mark lines up the timing marks and the chain and gears are slid over the crank (the keyway aligned with the crank's Woodruff key) simultaneously with the top gear over the cam.

Here you can see the cam was installed straight up with the dot on the cam gear matched to the "0" on the crank gear. This Rollmaster chain allows for very easy advancing and retarding of the cam by providing multiple keyways on the crank gear, which are marked for advancing 2°-8° and retarding 2°-8°. Degreeing the cam is a story unto itself and wouldn't fit here. Also, Taylor says that with accuracy of timing components today, he very rarely finds deviations from the manufacturers specs.

To install the fuel pump eccentric, Jim first bolts on one of its two pieces just to draw the camshaft forward to reveal its shoulder. This is because the installation of the timing chain would have pushed it toward the back of the block. Then the one piece is removed and the two pieces that comprise the eccentric are reunited and bolted on by simply aligning the tang with hole in the cam gear, mounting it and tightening the bolt to 45 lbs.-ft.

The timing chain cover will be installed next. Notice how the cover gasket extends all the way to the oil pan and the front oil pan gasket butts against it. Also note the small sleeves to ensure proper alignment for when the cover bolts get torqued to 35 lbs.-ft.

With the front of the engine buttoned up for the time being, we move to the valvetrain. Here we see the lifters doused with assembly lube, ready for installation. Jim commented that the cam lobes are treated to a dry film coating at Crane as well.

Rocker arm set screws get "painted" with moly lube prior to installation.

Just before the roller rockers are installed, we take a look at the valve springs. These Crane dual-with-damper units were set to 1.800-inch installed height. Seat pressure is 110 lbs. and open pressure is 260 lbs. Teflon positive valve seals are used on the intake and Viton positive valve seals are installed on the exhaust. Crane 7° steel retainers and locks are employed. The studs are HD GM 7/16 and the guide plates are stock.

Here are the Comp Cams 1.52:1 roller tipped rocker arms. They feature more contact area on the ball to distribute load and oil grooves that hold more oil. The roller tip reduces friction.

With the cam lobe on the base circle and the pushrods and rockers in place, Mark tightens down the rocker nut while turning the pushrod, until he feels drag on the rod. At this point there will be "0" lash between the rocker, rod and lifter plunger. The proper adjustment is one-half turn past zero lash, which he will do with a box wrench on the nut. Crane's Energizer pushrods are 5/16 diameter with stock length.

Then the Allen-headed set-screw is tightened, while the rocker nut is held with a box wrench to maintain the adjustment. The set-screw will tighten against the rocker stud inside the rocker nut and lock the assembly. Proper rod length has already been determined in this case.

The guide plates should be positioned very close to the rods, not forced to one side. These Crane rods are hardened; they won't wear out from rubbing on the guide plates, if it should happen. Though it looks caveman, shown is the preferred method for adjusting the guide plates. Jim says to be careful, as you can adjust too much and if you go too far, they crack. You can also see that the upper heat riser hole has been blocked permanently, so that a 1971 and earlier design intake manifold may be used without leaving the ugly upper heat riser holes exposed and having an exhaust leak.

Here's the front of the engine with the timing cover mounted and the valley pan installed and torqued to 15 lbs.-ft. Each was attached conventionally with no special tricks. Even the balancer is a stock GM Delco unit that was installed properly. The balancer bolt was torqued to 160 lbs.-ft. This was accomplished by placing a bolt in the rear crank flange and turning the crank until the bolt hits the engine stand and locks the crank in place. Then torque can be applied to the damper bolt at the front of the crank.

Taylor also measures and marks the balancer for 16° and 36° before top dead center so that the owner can check total timing instead of just initial, without a timing tape or a dial- back timing light.

A small item that is often overlooked is the oil filter adapter and its bypass spring, relief disc, spring retainer and self-tapping screw. Taylor disassembles and cleans each unit before installation to ensure proper operation. Many times there are nylon teeth from the old timing gear jammed in it. After bathing it in carb cleaner, Jim reassembles the unit and uses drop of Loctite on the spring retainer screw.

The intake, carb and distributor were installed next. This engine will use a 750 CFM Rochester (primary jets .073 or .074, secondary metering rods .052 or .054) with no spacer beneath it. Larry Rowe set up a GM HEI unit for street duty taking into account that low-compression engines need more timing. As a result, total timing is 34° all in by 3200, initial advance is 16°, mechanical advance is 18° and no vacuum advance is used. The intake is Edelbrock's classic Performer. It's of lighter weight than a stock unit and also shorter than the Performer RPM, so it will fit under a shaker scoop without modifications.
Happy building!