With the Mr. Gasket high-...
With the Mr. Gasket high- clearance chrome valve covers (for the roller rockers) and Pontiac silver-blue metallic paint, our mule looks just about ready to challenge the Stuska dyno water brake!
When we last discussed our Project Pure Poncho 455-based 467ci stroker engine, Craig Wise at Racecrafters had assembled the bottom end. We will pick up the assembly process in this issue and complete it in preparation for dyno testing.
To review, this mule engine is being built to test parts combinations in HPP. Bob and Craig Wise at RaceKrafters Automotive Machine have offered their services and will be using their Stuska dyno for future testing. Summit Racing Equipment provided most of the parts for this buildup except for the stroker reciprocating assembly and timing cover and valley pan that Butler Performance contributed.
 This Butler Performance...
 This Butler Performance reproduction timing cover was beautifully cast and is a good investment over a worn 40-year-old piece. It fits ’69-’79 engines with the 11-bolt water pump. To mount the Summit Racing Street & Strip Competition steel harmonic damper, Craig used a damper-installer tool and some Sunnen press lube on each side of to reduce the chance of galling, and then he torqued the bolt to the required 160 ft-lb.
The whys and hows of the parts choices for the initial combo were discussed in the last issue, which can be found using the keywords Project Pure Poncho in the search. Suffice it to say, we wanted to build a pump-gas engine that readers could relate to. We’ve included the engine buildup worksheet in this installment as well, so you can reacquaint yourself with the combo. Follow along as we complete the assembly, and please keep in mind that photos were taken during pre-assembly and assembly, so there may be instances where installed parts are seen in one photo and not the next.
Correction to the bottom-end story in the last issue: Photo #21 of the oil pan installation is out of order in the story. It should have been placed after the cam degree sequence #22-#23 and short-block photo #24. Sorry for the inconvenience.
HPP Engine Buildup Worksheet
4.185 / 4.250-in
 The damper is SFI-approved...
 The damper is SFI-approved and features engraved timing marks for easy tuning. Summit says that the special bonded elastomer will transfer heat more quickly than a stock damper making it beneficial for high performance applications. Craig then indicated TDC on the No. 1 cylinder to confirm the timing marks. The Summit damper and Butler Performance timing cover were perfect.
Stock ’75 455
Cooked, magged, line-bored, line-honed, decks squared with BHJ, bored and honed with torque plates
Summit Street/Strip, steel, elastomer, 6.610-in, SFI 18.1
Eagle forged H-beam, 6.800-in
Pin end honed to proper size, balanced, big end checked for proper size
Clevite, plain shell, tri-metal
Clean, check for proper clearance in rods
Butler/Ross forged flat-top with valve reliefs
Pin-fit, check size, clean
Ross, 0.990 floating, 0.155-in wall
Method used to retain piston pins in pistons:
Total Seal, moly top, ductile second, three-piece oil; 1⁄16, 1⁄16, 3⁄16-in
Rod bolts and head bolts:
Canton in pan
Canton in pan
Canton Racing Road Race Series 5-quart, wet-sump
Melling M54DS high-volume
Combustion chamber volume:
Maximum flow at 28 inches of pressure
|Lift ||Intake Flow CFM ||Exhaust Flow CFM|
|0.100 ||66 ||55|
|0.200 ||133 ||106|
|0.300 ||191 ||149|
|0.400 ||224 ||70|
|0.500 ||236 ||182|
|0.600 ||250 ||186|
Manley SS 2.11/1.77-in
Angles used in valve job:
45, 60, 75, and 82 deg, 82 is hand-blended into 75 deg.
45 deg, 12mm radius
Comp Cams, steel, 10-deg beehive
Comp Cams 10-degee, 11⁄32-in
K-line bronze liner
Comp Cams aluminum full roller, 1.65:1
Comp Cams Xtreme Energy hydraulic roller
Duration at 0.050:
Lobe Separation Angle:
Comp Cams roller
Comp Cams Beehive
Comp Cams double-roller
Holley 4150 HP 750-cfm, mechanical secondaries
Edelbrock Torker II
MSD Pro-Billet Ready-to-Run
Primary Tube Diameter:
Primary Tube Length:
 RaceKrafters designed...
 RaceKrafters designed and manufactured a splash shield specifically for Pontiac engines. Craig says, “The long-stroke crank throws a lot of oil into the lifter valley, so this part helps keep it in the crankcase. It also serves to block large pieces from dropping into the bottom of the engine should there ever be a valvetrain failure.”
 Moving to the cylinder...
 Moving to the cylinder head installation, the Fel-Pro head gasket is shown in place. The deck height of the block was set at 10.205 inches, which put the piston 0.010-inch down in the bore. With a head gasket volume 9.5 cc’s, a 96.2cc combustion chamber, and valve reliefs, the compression ratio is 9:1.
 The 6X cylinder heads...
 The 6X cylinder heads were fully ported by Cory Porter and fitted with Manley 2.11-inch intake and 1.77-inch exhaust valves—larger than the stock 1.66-inch exhaust valve. Craig explains, “We upgraded the exhaust valve size for two reasons: 1) It allows for the removal of more material to repair the valve seat area; 2) It allows for more bowl area under the valve to improve flow.”
 Craig removed the Comp...
 Craig removed the Comp Cams valvesprings on one cylinder and installed checking springs to take geometry and clearance measurements.
 With the gasket in place,...
 With the gasket in place, Craig lowered the head onto the block over the dowels and installed the head bolts temporarily.
 To improve valvetrain...
 To improve valvetrain durability, Craig had Cory previously modify and install BBC 7⁄16-inch studs. He placed a 7⁄16-inch washer under each stud to ensure the trunnion of the Pontiac rocker runs on the shank of the stud and not the threads (the weakest part). He then removed 0.300-inch of the thread length, so that the rocker’s set-screw has maximum thread engagement.
 Using a checking spring...
 Using a checking spring and an adjustable length pushrod to determine the pushrod length, Craig rotated the crank to get the cam on its base circle and installed the rocker arm and set it up so it’s nearly centered on the valve stem. Then he rotated the crank through the cam’s full lift while watching the sweep of the rocker arm. He says that to keep it as centered as possible throughout its travel, sometimes the rocker needs to start a bit off-center toward the lifter valley. When it’s in the center through its travel, the full lift of the cam is realized. If it’s too off-center, lift is reduced and the valve gets high side loads and prematurely wears the guides. The required pushrod length was 8.900 inches.
 To check piston-to-valve...
 To check piston-to-valve clearance, Craig rotated the crank to come up on the cam’s overlap and stopped at 10-degrees BTDC to check the exhaust, and then rotated 10-degrees AFTDC to check the intake. To perform the check, he used a dial caliper each time to measure from the retainer to the valvespring seat, he then pushed the valve rest of the way open to touch the piston and measured the same area. He subtracted the second measurement from the first to get the clearance, which was over 0.250 inch.
 The head was then removed...
 The head was then removed and Craig replaced the checker springs with the valvesprings and installed both cylinder heads. He used ARP grease under the bolt heads for an accurate torque reading and torqued them, starting in the center and working outward in an X-pattern for the sequence, in two increments—50 ft-lb and then 95 ft-lb.
 He coated the Comp Cams...
 He coated the Comp Cams roller lifters with 30-weight oil and installed them. Then he put in the Manley pushrods through the Comp pushrod guideplates and seated them in the lifters.
 Craig set the valve lash...
 Craig set the valve lash at zero plus a quarter-turn preload. These Comp Cams roller rockers feature needle-bearing trunnions to allow for valvespring loads over 350 pounds and are made from aluminum alloy.
 The Butler Performance...
 The Butler Performance billet-aluminum valley pan provides the clearance needed to run our hydraulic roller lifters. We chose the PCV-style, which uses a double-baffle design to thwart oil consumption through the PCV. When installing it, he warns not to over-tighten the hardware—as he has seen people do in the past—because it can distort the pan. He uses a pair of jamb nuts on each stud just below the height of the front and back sealing flanges of the block to act as a positive stop.
 Cory port-matched the...
 Cory port-matched the Edelbrock Torker II manifold prior to installation to compliment the massaged 6X cylinder heads. Craig and Bob specified this manifold: “It has the cross-sectional area to match head flow and displacement.” Craig first test-fit it without the front seal and then with it to ensure that the recess in the intake was deep enough and bolt holes lined up. When he installed it, he used Locktite Aviation gasket sealant (PN 30516) on the gaskets and on the bolt threads so oil can’t wick up. He inserted all of the bolts and just started to thread them in. He then tightened the front bolt at the water pump to draw the intake forward just a bit to make that front seal, well, seal. He then torqued the bolts to 20 ft-lb in a crisscross X-pattern working from the center out.
 For ease of operation...
 For ease of operation and tuning on the dyno, Craig and Bob chose a carb with some race features. The new model 4150 HP Holley mechanical secondary 750-cfm carburetor lacks a choke horn for the street, but does have threaded air bleed adjustments to make tuning easier. Other features include: smoothed venturi transitions for increased airflow, stainless steel throttle plates, notched floats, and Dominator style fuel bowls so the fuel line can be attached to either side. MSD’s Pro-Billet Ready-to-Run 6061-T6 aluminum distributor is easy to install with just a few wire connections, it has a maintenance-free magnetic pickup to trigger the ignition, eliminating points, and has an adjustable mechanical advance, not to mention other features to increase output and durability. The as-delivered setups of the carb and ignition will be used to break in the engine.
 Craig installed the Edelbrock...
 Craig installed the Edelbrock water pump with the plate, coolant transfer tubes, seals, and gaskets using the aforementioned gasket sealant. Edelbrock says its Victor-series aluminum, high-volume water pump’s CNC-machined housing has one-way internal passages designed to increase coolant flow at higher velocities, even at low engine speeds. Large curved-vane, CNC-machined, cast-iron impellers are also said to increase flow with less cavitation. Though not of paramount importance for dyno pulls, all of these features will be better utilized once the engine is installed in the car.