by Mike Mavrigian
Build/assembly and all photos by author
Our Lunati roller cam features 0.544" valve lift at intake and 0.560" at exhaust, with duration of 232 intake and 242 exhaust. Centerline is 108 intake and 116 exhaust.
CAMSHAFT AND TIMING
Dart thoughtfully provided anti-friction-coated cam bearings with their block. Each bearing is etched with a part number, and they must be installed in the proper order. Starting with the rear #5 bearing and working forward, the bearings are installed as follows: B388 (no. 5 bore), B387 (no. 4 bore), B386 (no. 3 bore), B385 (no. 2 bore) and B384 (no. 1 bore). Each cam bearing features three oil holes and a circumferential groove on the outer surface. Align one of the oil holes with each cam bore oil hole. With Dart’s coated cam bearings installed, the Lunati roller cam was coated with Royal Purple Max Tuff assembly lube (journals and lobes) and carefully inserted into the cam bores. Thanks to Dart’s precision machining of the cam bores and Lunati’s precision cam manufacturing, the bump stick slid in without a whimper and rolled like butter. Nice.
Royal Purple Max Tuff assembly lube was applied to the roller cam journals and lobes. This synthetic lube is very clingy and offers high pressure protection.
The camshaft retainer plate (thrust plate) is labeled for orientation.
The camshaft retainer plate bolts were tightened to 12 ft-lbs, with Loctite 242 locking compound applied to the threads.
Before installing the main bearing shells, pay attention to location. Each upper and lower bearing is labaled accordingly. Uppers install to the block saddles and lowers install to the main caps. Saddles and the rear of the bearings must be dry.
With main bearings installed in the block saddles and main caps, I applied a film of Royal Purple Max Tuff assembly lube to the bearing faces. This lube has excellent cling life to protect the bearings even if the engine won't be fired for a month or so (probably longer).
Our Scat crank features a 4.000" stroke, 2.750" (Cleveland) mains and 2.100" rod journals.
Crank thrust checked out at 0.0055", within the spec range.
The Dart block and Scat crank were designed to accommodate a one-piece rear main seal. Here the Victor rear seal(from our MAHLE-Victor gasket set) slid onto the crank precisely. The seal must be installed onto the crank before installing the main caps. I applied a light smear of 30W non-detergent engine oil to the seal lip prior to installation.
Our timing set is Melling's Performance kit P/N 40402. The crank gear features three keyways, allowing a setup for zero or 4 degrees advance or retard.
The Melling cam gear was test installed (along with an OE type fuel pump eccentric and an ARP 3/8” cam bolt & washer). Camshaft endplay was then checked using a dial indicator at 0.005”. The Melling crank gear (which provides three keyways for zero, 4 degrees advance and 4 degrees retard) slipped onto the Scat crank snout by hand so precisely and effortlessly that it almost made me giggle with glee. The fit was so nice that I couldn’t resist sliding it off and on a couple of times. Yeah, I know…I need to get a life. Today’s performance aftermarket leaders (like Scat, JE, Lunati and Melling, to name but four) have really led the way in terms of holding precision manufacturing tolerances. The days of having to make everything fit are quickly becoming a mere memory.
The Melling crank gear keyways are clearly marked.
The crank gear slid onto the snout easily with a very precise fit to both the snout and the keys. No need to tap and no slop. Outstanding.
Our cam gear bolt is from ARP, their P/N 155-1001. I applied a dab of Loctite 242 to the bolt threads and tightened to 45 ft-lbs once the gear and fuel pump eccentric were in place.
Camshaft endplay was measured at 0.005", using a magnetic-base dial indicator stand.
With crank, rods and pistons installed (detailed in this article), I degree-checked the camshaft timing using a Goodson degree wheel. OUR CAM SPECS Lunati hydraulic roller cam, P/N 51012, grind no. RRN1-232-242 Valve lift 0.544” intake; 0.560” exhaust (with 1.6:1 rocker ratio) Lobe lift 0.340” intake; 0.350” exhaust Duration at 0.050”….232 degrees intake; 242 degrees exhaust Centerline…….108 degrees intake; 116 degrees exhaust Timing @ 0.050” tappet lift…8 deg BTDC, 44 deg ABDC, 57 deg BBDC, 5 deg ATDC
ASSEMBLY OF PISTONS AND RODS
Our JE pistons were supplied with 0.927” floating pins, and four spiral locks per piston (two per side of each pin). Those who deal with spiral locks on a routine basis have developed a knack and are able to quickly install these by hand. Using your fingernails, gently spread the lock apart a bit. Insert one end into the lock groove and while gently pulling the exposed end out a bit (to help reduce the coiled lock’s diameter), work the lock into the groove using your fingers or with the aid of a small screwdriver until the lcok is fully inserted into the groove. However, folks like me who only deal with spiral locks maybe once a month or so take the easy way out. I use a dedicated installer tool from Lock-In-Tool. Using my .927” tool (dedicated for use with 0.927” pin size), each lock is gently spread apart a bit and then wound onto the tool’s spiral groove. A stopper clip is inserted into one side of the piston pin bore and a pin in then inserted into the piston’s pin bore (the stopper clip prevents the pin from being pushed out during lock installation). The tool (with lock installed) is inserted into the opposite end of the piston pin bore at a slight angle in order to start the end of the lock into the groove. The tool is then straightened out (in-line with the pin bore). While applying a constant firm pressure, twist the tool counterclockwise until the lock fully clicks into the groove. Granted, it takes a bit of practice, but once you get the hang of this tool, installing spiral locks is a breeze.
Our pistons are forged units from JE, P/N 232474. These slugs are intended for a 4.125" bore and a 1.280" compression distance. Coupled with our 4.000" stroke, 6.200" rods and a 9.480" deck height, our piston domes at TDC sit about 0.014" below deck. Pin diameter is 0.927" on these full-floaters.
Our piston domes feature -5cc valve reliefs. With our 70cc Trick Flow heads, we'll end up with about 10.9:1 compression.
Our Scat forged connecting rods feature a center-to-center length of 6.200" and I-beam construction. Scat did a really nice job on these rods. We didn't need to perform any corrections to pin bore diameter. Clearances were on the money and they weight-matched during balancing, straight out of the box.
Max Tuff assembly lube was applied to the piston wrist pins. The lube was liberally smeared along the entire outer surface. The pin is then inserted into the pin bore.
One method of installing spiral locks is by using Lock-n-Tool's installer. The lock is first wound onto the tool. This spreads the spiral and readies it for installation.
With the pin in place, a stopper clip is installed at one end of the pin bore. This prevents the pin from sliding out while using the tool to install locks at the opposite end. After first inserting the tool into the pin bore at a slight angle, the tool is then straightened out and rotated counterclockwise while applying pressure. The lock neatly winds into the lock groove in the pin bore. This particular set of JE pistons requires two spiral locks on each side of the pin.
Here a pair of spiral locks have been installed at one end of the pin bore. Once pistons have been assembled to their respective rods, the opposite side of the pin bore is then fitted with it's pair of spiral locks.
Once a pair of locks were installed in one side of the pin bore, the stopper clip is removed. The piston pin is removed, coated with lube (I use Max Tuff) and then reinserted into the lock-free side of the pin bore. Place the connecting rod small end between the pin bosses (make sure you have the piston correctly oriented t the rod …..remember that the piston valve pockets will be placed at the top of the cylinder bore, and the chamfered side of the rod big end must face the crank journal fillet. Slide the pin fully through the rod bushing and into the opposite pin boss in the piston. Then install the final two spiral locks.
The conventional method of installing spiral locks is to use your fingers and a small screwdriver. For first-timers, this will take some practice. For seasoned builders, this is second nature.
Always maintain a neat, organized and clean assembly area. Keep all pistons, pins, locks, connecting rods, rod caps, rod bolts and rod bearings organized prior to assembly. Our Lista workbench provides plenty of room and cleans easily, thanks to the tough urethane finish.
REMEMBER TO ALWAYS KEEP THE RODS AND ROD CAPS MATCHED! Connecting rod big end bores are finished with the caps installed. Never mix caps! All rods and their caps should be numbered to identify cap and rod. The Scat rods feature laser-etched numbers on rods and caps (these numbers are placed on the same side). Wipe the rod big end bearing saddles (and cap saddles) with a lint-free towel. The saddles must be clean and dry (no oil). Install the rod bearing shells (the backside of the bearings are marked for position…upper bearings are installed to the rod saddles and lower bearings are installed to the caps).
I used MAHLE Clevite rod bearings, sized for our 2.100" rod pins.
FILE FITTING OUR RINGS Our JE piston kit P/N J10008-4125-5 included file-to-fit rings. The top rings are ductile plasma moly barrel faced, P/N 8 S14125-5-116DMB (1/16”). The second rings are iron phosphorous taper, P/N 8 P24126-5-116IPT ( 1/16”). The oil ring package is P/N 8 H34125-0316FCUF (3/16”).
Squaring the rings in the bore is easy with Summit's ring squaring tool. The tool adjusts for bore diameter and features a stepped underside that evenly pushes the ring down evenly into the bore for accurate gap measurement.
I filed the top rings to achieve a gap of a slightly loose 0.018” (but too tight to fit a 0.019” feeler gauge). The second rings were filed to obtain a slightly loose 0.020” gap (but too tight to fit a 0.021” gauge).
Ring filing was accomplished on our Summit bench-mounted rotary ring filer. This features a diamond-particle wheel and a simple hand crank. This tool works great and offers and easy and economical method of custom filing rings.
After file fitting rings, carefully deburr the filed edges using a fine flat file.
For high performance street applications, JE recommends a top ring gap of 0.0045” gap for every inch of bore diameter (4.125 x 0.0045 = 0.01856”). JE also recommends a second ring gap of 0.005” per inch of bore diameter (4.125 x 0.005 = 0.02062”). JE recommends a minimum gap of 0.015” for oil ring rails. I checked ours out of the box at 0.028”. When checking each ring in its intended cylinder, I squared the ring using Summit Racing’s adjustable ring squaring tool, which makes quick work of positioning the ring squarely in the bore. Each ring was filed on Summit’s manual-crank ring filing tool that features a diamond wheel. After all top and second rings were filed to fit, I carefully deburred the freshly-filed edges with a fine flat file. After filing, carefully clean each ring to remove any metal dust. Once the piston rings have been verified for cylinder fit and end gap, install the rings and apply a liberal amount of clean 30W non-detergent oil onto the ring package and the piston skirts. Gently rotate each ring to verify smooth rotation.
JE's piston set included a full set of file-fit rings to tailor-fit our 4.125" bores.
When installing the oil ring package, be sure to keep the expander ring ends butted as you install the lower and upper oil ring rails.
Our pistons and rods, with rings installed, are neatly organized on our Lista bench, ready for installation. Maintaining order helps the job go smoothly and avoids mixups.
Before installing the rods and pistons, be sure to meticulously clean all cylinder bore wall surfaces with a lint-free towel. Wipe until the towel is absolutely clean. Then apply a film of clean 30W non-detergent engine oil to all cylinder wall surfaces. Do not use a synthetic oil on the walls, as this can hamper piston ring seating during engine operation.
Make sure that the cylinder bores are absolutely clean (wipe with a fast-evaporating solvent such as mineral spirit and a clean lint-free towel). Once you are certain that the bores are clean, apply a film of clean 30W non-detergent oil to the cylinder walls. Orient the piston rings for proper gap location. There are several schools of thought with regard to gap placement. Basically, as long as the gaps don’t align (ring to ring), you should be OK (rings will tend to rotate a bit during engine operation anyway). However, JE Pistons provides a gap placement recommendation with their rings, and since they’ve done an incredible amount of research in this regard, I tend to follow their specs. Refer to the following “Piston Rings” section for gap locations.
With rod bearings installed on the rod and rod cap saddles, apply lubricant to the bearing faces. I use Royal Purple Max Tuff. Smear the lube evenly over the entire bearing face area.
Apply 30W non-detergent oil onto the ring package. Gently rotate the rings to assure smooth operation. Carefully re-align all rings to place gaps in the proper orientation.
The rings were checked for fit to the pistons. Side clearance (the difference between the ring groove and the ring thickness) checked at 0.017 - 0.002” on all of our rings. Back clearance (the difference between the depth of the ring groove to the radial thickness of the ring) checked out at approximately 0.005”. When the rings were installed onto the pistons, I oriented the gaps according to JE’s recommendations. Viewing the piston from overhead with the front of the piston facing 12 o’clock, the oil ring expander gap was at approximately 3 o’clock. The bottom oil ring rail gap was placed at the 11 o’clock position. The upper oil ring rail gap was placed at 7 o’clock. The second ring gap was placed at 9 o’clock, and the top ring gap was at 3 o’clock. Before installing the piston/rod package, rotate the crank to place the intended rod pin at the bottom-dead center position (this gives you room to begin moving the rod towards the pin without the risk of nicking the crank with the rod big end). Next you’ll need to compress the ring package. Personally, I hate the adjustable barrel type ring compressors. My favorite is the single-piece billet compressor. This features a taper on the inside diameter, allowing the ring package to easily enter the compressor, and the decreasing diameter serves to compress the rings before they approach the top of the cylinder bore. For this build, I used ARP’s ring compressor P/N 900-1250, specifically sized for our 4.125” bore size. Make sure that the ring gaps are positioned as needed, then slip the rod big end into the compressor, until the piston skirts enter the compressor. Gently continue to insert the piston, making sure that each ring enters the tool. Once the entire ring package has entered the compressor, insert the rod big end into the cylinder bore (make sure that the rod big end chamfered side faces the crank’s rod pin fillet) and is aligned to the rod pin. Place the compressor tool firmly flat against the block deck. Firmly push the piston dome until the entire ring package has entered the cylinder bore. Continue to push the piston down into the bore with one hand while guiding the rod big end with your other hand until the upper rod bearing gently seats onto the rod pin. Pay attention to make sure that you don’t allow the rod big end edges to hit the crank’s rod pin. Once the rod is seated, install the rod cap. The Scat connecting rod caps feature dowel sleeves. Manually engage the dowels into the rod and insert the rod bolts by a few threads. Using a clean plastic hammer, gently tap the cap roughly into place. Don’t use the rod bolts to completely draw the caps into place. Once the caps are initially seated, then tighten the rod bolts, alternating side to side until the cap is fully seated. Tighten to roughly 10-20 ft-lbs. Once the opposite-bank piston/rod assembly is installed in the same manner, then fully tighten both rods’ bolts to full value.
Instead of using the atiquated barrel-type ring compressors, the slick way to go is to use a dedicated-per-cylinder-bore-diameter billet compressor, such as this one from ARP. The inside diameter of the tool is tapered, forcing the rings to smoothly compress as the piston passes through the compressor.
The billet tapered compressor is clearly identified according to bore diameter. Yes, you need a specific compressor for each bore diameter (per engine build), but using this type of compressor is much easier to use and virtually eliminates the danger of ring damage during installation.
Slip the rod through the top of the ring compressor, and slip the piston into the compressor until the entire ring package is captured inside the compressor.
With the rod and piston oriented properly and the crank rod pin placed down near bottom-dead-center, gently but firmly push the piston down through the compressor until the ring package has entered the bore. Once you use this type of ring compressor, you won't want to go back to the old spiral wrapped barrel type compressor ever again. Next, while guiding the connecting rod, carefully push the piston further until the upper rod bearing gently seats onto the crank rod pin surface. Place the rod cap (with lubed bearing) onto the crank pin, aligning the cap-to-rod dowels. Finger-install moly-coated rod bolts, and gentlytap the cap into place while holding the rod. This assures alignment, as opposed to drawing the caps in place during tightening.
There are two methods that you can use when tightening connecting rod bolts. You can either use a torque wrench and tighten to the specified value (in this particular case, our 7/16” 8740 ARP rod bolts feature a recommended torque value of 63 ft-lbs). Or, you can tighten the rod bolts by monitoring bolt stretch. This involves the use of a bolt stretch gauge. The stretch method is theoretically more precise, since it allows you to ignore frictional variables by achieving the recommended (and consistent) bolt stretch and resulting clamping load. First, place a rod bolt onto the stretch gauge and preload the plunger by about 0.050”, and then zero the indicator needle on the gauge. Then set the gauge aside (without disturbing the gauge setting). Begin to tighten the rod bolt, and routinely place the gauge onto the bolt to measure how far it has stretched. Scat provided a recommendation of 0.005” maximum stretch for our ARP bolts. So in this case, you would continue to tighten until you read about 0.004” stretch. This is a time consuming process, but it’s a bit more accurate than relying on torque value alone. Either way is acceptable. All performance aftermarket rod and rod bolt makers will provide both torque and stretch specifications.
In order to tighten the rod bolts using ther stretch method, I first install a rod bolt to the gauge anvils and zero the indicator gauge.
The rod bolt is tightened in increments, stopping after each step to check rod bolt stretch with the stretch gauge. This is a more time-consuming process than simply tightening by torque value, but it's more accurate in terms of achieving proper and consistent clamping loads.
Once all eight piston/rod assemblies were fully installed, I used a beam-type torque wrench on the crank snout to check how much force is required to rotate the crank (not necessary, but it’s fun to find out). In our build, only 15 ft-lbs was required for crank rotation. She rolled like butter.
OIL PUMP AND PICKUP
Our oil pump is a standard pressure/standard volume unit from Melling, P/N 10832. This cast iron pump features a gerotor set assembled to an extended drive shaft that allows for additional support in the cover. Supporting the drive shaft in both the housing and cover eliminates dynamic shaft deflection at increased RPM levels. The cover is also doweled to the pump housing to assure shaft bore alignment. The housing and cover are CNC machined and phosphate coated for wear and rust prevention. The relief valve also features a pressure adjustable screw-in plug. The pickup is from Moroso (designed for use with their pan and the Melling pump), P/N 24507.
Our oil pump driveshaft is from ARP. The hex tip that features the stopper clip is installed facing up towards the top of the engine block.
With the block upside down, the oil pump driveshaft is inserted, guiding it into the guide hole to align the shaft towards the distributor. The stopper clip prevents the shaft from being pulled out of the oil pump during any future distributor service.
Before installing the oil pump, an ARP oil pump driveshaft, P/N 154-7901 was installed from the oil pump side, with the distributor tip aiming upwards toward the top of the block. A stopper washer on the shaft prevents the driveshaft from accidentally being pulled out during any future distributor service.
The oil pump-to-block gasket is positioned onto the block prior to oil pump installation.
Our oil pump is a standard volume performance unit from Melling, P/N 10832. This is a beefy pump with added support for the driveshaft to eliminate shaft deflection at higher RPMs.
The oil pump mounting bolt is tightened to 25 ft-lbs.
The Moroso pickup (with gasket in place) mounts to the Melling pump with a pair of 5/16" bolts, tightened to 18 ft-lbs, with loc washers and Loctite 242 on the bolt threads.
Using our Goodson degree wheel and Foster Tool's lift indicator, we verified our cam timing.
The Foster Tool's lift indicator slides into a lifter bore. The spring-loaded plunger contacts the cam lobe. The tool body features an expandable collar that locks it securely in the bore. Rotate the cam to locate base circle, preload the plunger slightly and zero the gauge. You can now accurately monitor lobe position during opening and closing. This is a very handy tool.
A standard OE replacement type cast aluminum cover was obtained from Silver Seal, their part number TW6600. This is a “universal” 351W timing cover. It’s a very nice piece (I test fitted it first and found it to match-up perfectly), but since it’s an OE style, I dressed the edges, eliminating any minor casting flashings, etc. It cleaned up in a heartbeat. This piece was also primed, basecoated and clearcoated (sprayed at the same time as the block).
A new front cover from Silver Seal (shown here as delivered) was smoothed out (as was the block exterior) and basecoat/clearcoat painted to match the block.
The front cover is installed prior to oil pan installation. The front cover (and water pump) was secured using a set of stainless fasteners from Totally Stainless.
I installed a new front seal into the cover’s seal bore (seal installed from the front of the cover), using a seal driver to prevent cocking the seal. Place a clean block of wood on a bench, cover the wood with a clean towel and lay the timing cover onto this rest. This provides a backstop for the cover while tapping the seal in place to prevent damaging the cast aluminum cover. A pair of ½” OD dowel sleeves were installed to the cover (in the lower recessed dowel counterbores). The timing cover-to-block gasket was lightly coated with RTV, and the front seal was lightly lubed with Max Tuff. The cover was installed to the block using a stainless steel timing cover bolt set from Totally Stainless. With the dowels aligned to the block’s front dowel counterbores, the cover was tapped into place and the 5/16” cover bolts inserted. All of the 5/16” bolts were tightened to 18 ft-lbs (in a crisscross alternating pattern to avoid cover warpage).
Our Meziere electric water pump P/N WP311B (a thing of beauty beyond compare) is a full-frame pump that does not require an adapter for mounting to an OE style timing cover. The pump offers a 55 GPM free-flow rating and a 3000+-hour life expectancy, suitable for street or strip use. Meziere also offers this pump in either a right or left side lower hose connection version. A stainless steel large diameter main shaft and high performance ceramic seal provide ultra-durability for high performance abuse. Offered in various finishes, I opted for the blue anodized finish, which is just plain mouth-watering gorgeous, and adds a bit of color to our otherwise monochrome color theme. Both sides of the pump gasket were lightly coated with RTV, and the pump was installed using a set of stainless steel fasteners from Totally Stainless (Meziere provides a full set of stainless fasteners, but I decided to maintain a theme of hex and 12-point male heads in this build wherever possible). All of the 5/16” bolts were snugged to a value of 18 ft-lbs.
The Meziere water pump is machined from billet aluminum and flows 55 GPM.
The Meziere pump features a full-size back, allowing a direct bolt-on without the need for an adapter plate.
Meziere pumps are simply outstanding components. And the beauty factor doesn't hurt either.
The splash of anodized blue against the monochromatic background of the block really adds some pizazz.
Our oil pan is Moroso’s black powdercoated front-sump unit, P/N 18507. Features include a 7-quart capacity, an oil retention baffle and a kick-out sump for increased capacity to improve oil control under hard acceleration, and for increased ground clearance while providing added capacity. Since this pan was not designed to clear all 4-bolt front/rear main caps, I found an interference at the outboard corners of the rear main cap (the front cap cleared just fine). The solution was to slightly chamfer the outer corners of the Dart steel rear main cap, which was really no big deal during test fitting.
I installed ARP stainless studs at the pan rail. As opposed to using bolts, the studs allow easy gasket and pan alignment. The MAHLE Victor oil pan gasket features steel inserts that provide positive no-guess crush during tightening.
Our Moroso pan features a 7-qt kick-out front sump. A slight chamfering of the rear main cap outboard edges was necessary for pan fit, only because this particular pan wasn't designed for use with 4-bolt main caps.
Pan mounting was handled with a set of ARP stainless steel studs, ARP P/N 454-1904 instead of bolts. Oil pan studs not only look cool, but studs make it a bunch easier to service a pan in the vehicle, if the need ever arises, since they serve as guides for both the pan and its gasket. A series of 16 ¼” studs were installed to the block pan rail, along with two 5/16” studs at the rear. The timing cover bottom was also fitted with two ¼” studs (outboard) and two 5/16” studs (inboard). A Victor Reinz oil pan gasket was selected, fitted with stainless steel hole inserts. This allows you to fully tighten, bottoming out against the inserts, without fear of over-crushing the gasket. The gasket fit flawlessly….an absolutely perfect tailor-fit to out block. Note: the front and rear seal areas feature small tabs that enter recesses at the base of the front and rear seal radiuses. It’s not a bad idea to apply a small dab of RTV into these recesses before installing the gasket. With the pan in place, all ¼” ARP 12-point nuts were snugged to 80 in-lbs, and the four 5/16” ARP 12-point nuts were tightened to 18 ft-lbs. Note: deepwell 12-point sockets are needed to service these nuts (5/16” sockets for the ¼” nuts and 3/8” sockets for the 5/16” nuts). Once the oil pump and pickup were installed, I wanted to verify our pickup-to-pan-sump clearance. I measured the distance from the block pan rail to the pickup screen, and then measured the distance from the oil pan’s rail to the bottom of the sump. This check showed a clearance of about ½”. Generally speaking, a clearance of 5/16” to ½” is considered acceptable. You don’t want the pickup to contact the sump floor, and you probably don’t want more than about 5/8” clearance.
INSTALLING THE CRANK DAMPER
I pre-measured our crank snout diameter and the I.D. of the damper at a 0.001” interference fit. I applied a thin film of Royal Purple Max Tuff lube onto the snout and keys. With the timing cover installed, I drew the damper onto the snout using a PRW damper installer tool. This features a threaded mandrel and a selection of threaded pilots (simply choose the correct pilot to fit the crank snout threaded hole). A bearing and hardened washer are slipped over the mandrel. With the tool’s pilot threaded into the snout, the mandrel’s hex head (at the outer end) is held stationary while the large mandrel’s nut is tightened. This smoothly draws the damper onto the snout without the need to pound it on with a hammer (a hammer is never a good idea). Once the damper bottoms out, unthread the tool from the snout. If you don’t own one of these tools, crack your wallet open and buy one.
Our PRW damper P/N 2430203 is a 6.5" neutral balance unit (since or crank was internally balanced). Interference fit to the Scat crank snout was ideal at about 0.0015" and drew onto the snout smoothly. This is a very nicely finished damper, with a black powdercoat finish and clearly etched timing marks. The unit is also SFI certified.
A proper damper installation tool is a must. Never try to force a damper onto the crank snout with a hammer. This PRW installation tool features a long threaded mandrel with interchangeable tips (to fit specific crank snout thread size) and a bearing captured by hardened washers.
With the tip of the mandrel threaded into the crank snout, hold the hex at the outer end of the mandrel steady while turning the hex nut clockwise to smoothly and safely draw the damper into place. The damper was then secured with an ARP snout bolt P/N 150-2501, snugged to 80 ft-lbs.
Our flexplate is from PRW, P/N 1830213. This is a 157-tooth unit, secured to the crank with ARP flexplate bolts tightened to 80 ft-lbs.
OUR FASTENER TORQUE SPECS
MAIN CAP TORQUE SPECIFICATIONS
Dart specifies the following torque values for their main cap bolts… (Note: all torque values listed are based on the use of oil on threads and bolt head undersides) INBOARD ½”-DIA BOLTS………………………………….105 ft-lbs (w/oil) OUTBOARD 7/16” SPLAYED BOLTS AT CAPS 2-3-4…… 65 ft-lbs (w/oil) OUTBOARD 3/8” BOLTS AT CAPS 1 & 5…………………. 35 ft-lbs (w/oil) (Note: with all cap bolts in place, tighten the ½”-dia bolts first, followed by the 7/16” outboard splayed bolts, followed by the 3/8” outboard bolts) CONNECTING ROD BOLT TORQUE ARP 7/16” 8740 ROD BOLTS………………………………..63 ft-lbs (w/moly) (or tighten by monitoring bolt stretch…. 0.004 – 0.005” ….0.005” max) CAMSHAFT SPROCKET BOLT ARP 155-1001…………....45 ft-lbs CAMSHAFT RETAINER PLATE BOLTS……9-12 ft-lbs OIL PUMP TO BLOCK 3/8” BOLTS………….25 ft-lbs OIL PUMP PICKUP 5/16”X 18 BOLTS………18 ft-lbs DAMPER BOLT ARP 150-2501………………80 ft-lbs (OE spec) FLEXPLATE……………………..…………….80 ft-lbs (OE spec) TIMING COVER TO BLOCK….……………..15-18 ft-lbs WATER PUMP TO TIMING COVER.………..18 ft-lbs