This installment in our LS 5.3L "retro build" covers installation of our hydraulic roller lifters, cylinder heads, pushrods and rocker arms, completing the valvetrain.
Build, text and photos by Mike Mavrigian
While there’s nothing to complain about with the original casting number 862 aluminum heads (GM P/N 12559862), making them flow much better was a simple task. Total Engine Airflow, well-known for their development of LS cylinder heads, already had a CNC program for reworking the intake and exhaust ports to elevate intake runner volume from the original 200cc to 220 cc; and exhaust ports from the original 70cc to 78cc.
The original 5.3L aluminum heads have been CNC ported by Total Engine Airflow to increase runner volumes and flow CFM. Also, the original 1.89” intake valves were replaced with LS1 2.00” intake valves (exhaust valve diameter was kept at the original 1.570” diameter). The 61.15cc chambers were left unmodified. However, the cylinder head decks were milled 0.030” to reduce chamber volume to 58cc. In conjunction with stock block deck height, stock stroke, stock rod length and our flat-top pistons (the OE 5.3L pistons feature valve reliefs), this produces approximately 11.0:1 compression ratio, as compared to the OE compression ratio of 9.5:1. Because of the increased valve diameters, the stock size 5.3L head gasket slightly hangs into the chambers, so we switched to 5.7L LS head gaskets (which offer a 3.900” gasket bore).
CYLINDER HEAD SPECS
OE MODIFICATION Combustion chamber volume……61.00cc ….…………… 58cc Compression ratio………………..9.5:1 …………………. 11.0:1 Intake port volume……………….200cc ………………… 220cc Exhaust port volume…………….. 70cc ………………… 78cc Intake valve diameter…………… 1.89” …………………. 2.00” Exhaust valve diameter…………. 1.55” ………………….. 1.55” Valve springs: These were changed from the OE beehive springs to Trick Flow Pacoloy #TFS-15408 beehive (130 lb @ 1.800” / 318 lb @1.200”). These springs are a bit heavier than OE LS6 springs. Note: Do not skimp on valve springs by re-using original OE springs. Also, be aware that if using LS6 springs, not all of them feature the same coil-bind height. OE LS6 springs are available in several versions, so you never know what you’re getting. The best approach is to obtain quality aftermarket springs that are consistent.
OE CYL HEAD FLOW (CFM)
LIFT INT EXH 0.100 ………….. 63 ……….. 54 0.200 …………. 128 …….. 93 0.300 …………. 179 …….. 121 0.400 …………. 210 …….. 145 0.500 …………. 218 …….. 163 0.550 …………. 221 …….. 168 0.600 …………. 226 …….. 174
MODIFIED CYL HEAD FLOW (CFM)
The OE heads were treated to a CNC massage, increasing intake port volume from 200cc to 220cc. Exhaust port volume was increased from 70cc to 78cc.
Closeup of a cathedral intake port after CNC machining.
Exhaust ports were slightly enlarged from the OE 70cc to 78cc volume.
Bowls were slightly blended and seats were cut to accommodate the 2.00" intakes and 1.55" exhaust valves.
New GM 5.7L LS1 valves were checked for fit and installed. Nothing fancy here. Remember: this is a "budget" build. These valves will certainly be adequate for moderate high performance street use.
Combustion chambers were reduced in volume from 61cc to 58cc (by decking the heads by 0.030"), increasing compression ratio to 11:1. Exhaust valve diameters were retained at 1.55", but the intake valves were increased from the OE 1.89" to 2.00" head diameter.
The OE beehive springs were replaced with stronger Trick Flow Pacoloy springs, P/N TFS-15408. These valve springs will better accommodate higher revs, with less fatigue and longer life.
Plastic/composite lifter "buckets" serve to guide the roller lifters, maintaining roller-tip plane to the cam lobes. This eliminates the need for lifter dogbones or lifter bridge plates.
The hydraulic roller lifters (we're using new lifters from Crane) are inserted into the OE lifter trays (often called lifter buckets). The flats on the upper lifter bodies register into the flat-sided cavities in the lifter bucket. This keeps the lifters from rotating, maintaining proper roller-to-camshaft lobe orientation. Experience has shown that excess oil tends to build up inside the lifter bucket cavities. In order to aid in oil drainback, we drilled a 0.250" hole in the outboard wall of each lifter cavity, close to the cavity floor. Adequate oil will still be delivered to each lifter, but the unecessary oil buildup is eliminated.
This view inside the top of a lifter bucket reveals the oil-dispersion ridges that help to deliver oil to the lifters. However, there is a tendency for excessive oil buildup inside these cavities. To relieve this, and to aid in oil drainback, we drilled a single 0.250" hole in the wall of each cavity (see hole in the lower area of this photo).
Here's a view of the outboard wall of a lifter bucket. Notice the oil drain holes that we drilled.
Each lifter "snaps" into the lifter bucket receptacles. When fully engaged, this not only registers the lifter in plane with the cam lobe, but also lightly secures the lifter to the lifter bucket, allowing you to handle a group of four lifters and bucket as a single unit.
Here a group of four Crane roller lifters have been installed to a lifter bucket. Notice how all rollers are in-plane to properly contact the camshaft lobes.
Each lifter bucket is installed to the block with a single 6mm shouldered bolt. Due to the slightly taller Comp Cams lifters, a Comp spacer is installed between the bucket and block to compensate for the taller lifter height. Each 6mm lifter bucket mounting bolt is tightened to a value of 106 in-lb.
Once the lifters/buckets are installed to the block, position the head gaskets. We used Mahle Victor MLS gaskets. Be sure to install the lifter buckets before installing the gaskets, since the buckets are trapped by the gaskets.
Pay attention to head gasket orientation. The Mahle Victor MLS gaskets are clearly marked "Front" for positioning.
Carefully position the cylinder heads onto the block decks, registering to the deck dowel sleeves.
Instead of using OE torque/angle head bolts, we opted for vastly superior ARP head bolts, which require only a torque spec, eliminating the need for additional angle-tightening.
Before installing the head bolts, apply a bit of ARP moly to the underside of each bolt head.
Also lightly coat each head bolt washer with ARP moly lube. This greatly reduces frictional variables during bolt tightening.
Apply ARP moly to head bolt threads as well. This isn't "just another lubricant." ARP moly is specifically designed to reduce frictional losses during bolt tightening, allowing you to achieve a more accurate torque value.
When using OE head bolts, the 11mm bolts are to be tightened with an initial 22 ft-lb, followed by additional angle tightening by 76 degrees. The 8mm bolts are tightened to 22 ft-lb, followed by 34 degrees of additional rotation. When using ARP head bolts, you'll use torque value only, tightening the 11mm bolts to 80 ft-lbs (in three steps) and the 8mm bolts to 22 ft-lb. Be sure to follow the OE tightening sequence.
Shown here is the OEM cylinder head bolt tightening sequence. Tighten the 11mm bolts first, followed by the 8mm bolts. It's important to carefully follow the tightening pattern to provide an equal distribution of clamping load.
While any quality, properly-calibrated torque wrench will do the job, we relied on Snap-On's digital torque/angle wrench. Set the torque value desired, and when you approach that value, the wrench buzzes and vibrates, allowing you to monitor the display and precisely hit the desired value. It operates the same when in angle mode (if using OE bolts). Pretty nifty.
Here, our heads have been fully installed, and we're ready for rocker arm installation.
INSTALLING THE ROCKER ARMS
You may recall the upgrade of the rocker arm trunions (see Part 2 of this series). As far as I'm concerned, this is a MUST-DO if you plan to use OE rocker arms. The original rocker arm trunions are not durable. The needle bearings tend to walk out of the cheap tin cages, and wreak havoc on the rest of the engine. At this point I should qualify this opinion. For daily-driver use, the upgrade probabaly isn't necessary. However, if you plan to swap out cams and upgrade to stiffer valve springs, and plan to "play" with the engine (higher revs, etc.), then this modification IS necessary. Of course, the best move would be to replace the rocker arms with a set of forged aluminum full-rollers (Harland Sharp, Comp Cams, etc.). The OE powder metal rocker arms are actually pretty decent in terms of durability and should be OK for a mild build, but if you're planning to make the engine scream, spend the dough and move to high quality full-roller aftermarket arms. But, as stated earlier, if you want to keep your costs down and re-use the OE rockers, you should at least upgrade the trunions. We used a set of Comp Cams' trunion upgrades, which included new beefier trunions and fully-caged, high-quality trunion bearings. The changeover will take you about an hour or so. It isn't difficult to do, especially if you use Summit Racing's trunion press kit (again, see Part 2 of the series). The upgrade is well worth the trouble. Spending a couple of bucks and a wee bit of your time beats the need to completely rebuild the engine if/when the OE trunion bearing needles splatter out and make a mess. .
A new set of Comp Cams pushrods were selected, after careful measurement for pushrod length. We chose a length of 7.400" for both intake and exhaust locations.
Comp's pushrods are laser-etched with length and wall thickness dimensions.
OE rockers (prior to the trunion upgrade) and light checking springs were used during checking to determine pushrod length and valve-to-piston clearance. Note that this cylinder head version requires the use of a rocker pedestal rail. Valve to piston clearance measured out at a healthy 0.185" at the intakes and 0.194" at the exhaust valves.
Prior to installing the pushrods, the Comp pushrod tips were coated with Comp's high-pressure assembly lube.
Valve tips were also coated with Comp's assembly lube. All friction contact areas must be lubed with a high-pressure lubricant, including pushrod tips, valve stem tips, rocker pushrod cups and rocker valve contact surfaces.
Rocker pedestal rails are positioned onto the heads. Certain LS heads feature cast-in rocker pedestals, while others require the use of common add-on rails.
Be aware that LS intake rocker bolt holes are open, while exhaust rocker bolt holes are blind. Intake rocker bolts must be coated with a thread sealing compound. If you ignore this step, you'll end up with a bunch of nasty vacuum leaks.
Coat all exhaust rocker bolt threads with ARP moly. On all intake and exhaust rocker arm bolts, also apply a dab of moly lube under the bolt heads. This reduces friction and aids in accurate clamping loads during bolt torquing.
Snug all rocker arm bolts by hand. Here we're using the SHCS (socket head cap screws) supplied with the Comp Cams trunion upgrade kit.
With the respective cam lobe positioned with it's lifter contacing the lobe's base circle, tighten the rocker arm bolt to a value of 22 ft-lbs.
With all rocker arms fully installed, we're ready to install the block top cover plate and valve covers.
The block top cover plate is sealed using a Mahle Victor metal-core gasket that features an elastomeric bead seal on top and bottom. No additional sealant is required.
The top cover plate design will vary, depending on the LS version. The 5.3L LS engine features twin knock sensor locations in the block valley. The original top cover plate features extended bosses that meet these sensor locations. Other LS versions may feature DOD (displacement on demand) oiling towers. If your block does feature these oiling towers, the top cover plate must feature short bosses on the underside of the cover, with O-rings that seal against these towers.
Here the block top cover plate is placed into position. Notice that we painted the block, heads, oil pan and top cover in "old school" Chevy orange, in an attempt to emulate an early smallblock Chevy.
This overhead view shows one of the two knock sensor cavities in the top cover. The bottom of the cover boss features a sealing ring (to seal off oil from the cam valley area). Each of the threaded holes in the block (for the knock sensors) features a 10mm x 1.5 hole. These threaded holes are blind and are not open to oil.
The top cover is secured with 8mm x 1.25 bolts, which are tightened to a value of 18 ft-lbs. Do not overtighten!
Before installing the valve covers, take the time to replace the valve cover gaskets. Here we install a formed sealing gasket (from our Mahle Victor gasket set). These seals feature an upper lip that "locks" into the valve cover's gasket groove. Take your time to work the seal around the cover, making sure that the seal is properly engaged along the entire perimeter.
Also, it's a good idea to install new rubber grommets at all four valve cover bolt hole locations (these are also included in the Mahle Victor gasket set).
Tighten all four valve cover bolts to a value of 106 in-lbs.
Since we're not planning to use OE knock sensors (remember...we're running a carb setup with MSD's ignition controller), I decided to fabricate a pair of aluminum plugs to cover the knock sensor holes in the top block cover plate. This will provide a better appearance, and will prevent debris from entering the unused holes. Starting with 2.500"-diameter aluminum round bar stock, I used my shop's lathe to create these plugs. The top "hat" features a diameter of 2.400". The lower shoulder area was turned down to 1.940"-diameter. This allows the plug to nestle into the cover plate hole, while the larger diameter top section rests on top of the cover plate. Overall plug thickness is 0.483". The top "hat" section thickness is 0.110". I also machined a radius groove near the base of the shoulder to accept a sealing O-ring. The required mounting bolt size is 10mm x 1.5, approximately 90mm in length. I drilled the centered bolt hole in each plug at 0.395"-diameter. While clearance between the plug and the bottom of the intake manifold runners will allow the use of hex head bolts or socket head cap screws, I may opt to countersink the plug bolt hole to allow the use of a flat-top screw. I'll provide final info on this in the next article.
Side view of one of my fabricated plugs. I slightly chamfered the top and bottom edges of the top hat section to eliminate sharp edges. The installed O-ring outer diameter of 2.015" provides a minor snug interference fit into the top cover plate bore, enough to seal out moisture and debris. The radiused O-ring groove was machined at a width of 0.080" and a depth of 0.060". The groove was centered about 0.170" from the plug bottom.
The fabricated plugs provide a lightly-snug hand-fit into the top cover plate holes.
The aluminum plugs certainly improve top cover plate appearance (as opposed to simply leaving two big unused holes). I'll likely paint the plugs in matching Chevy orange.
NEXT ARTICLE: In our next installment of this build series, we'll cover intake manifold prep and installation, along with carburetor, exhaust headers, water pump, our custom coil pack covers and our MSD ignition controller kit.
OUR REPLACEMENT PARTS LIST
ITEM MFG PART NO. PISTONS Sealed Power H1132CT (+.25mm) PISTON RINGS Hastings 2M4978010 CONN. RODS GM 12577583 MAIN BEARINGS Mahle-Clevite MS-2199H ROD BEARINGS Mahle-Clevite CB663A CAM BEARINGS Mahle-Clevite SH18145 GASET SET Mahle-Victor HS54340 CYL HEAD BOLTS ARP 134-3609 MAIN STUDS ARP 234-5608 ROD BOLTS ARP 134-6006 CAM GEAR BOLTS ARP 134-1003 OIL PUMP Melling 10295 TIMING SET Melling 3-3SRH60SA ROCKER ARM TRUNION UPGRADE Comp Cams 13702-kit CAMSHAFT Crane 144-HR-228/3241-252-10 4A VALVE SPRINGS Trick Flow TFS-15408 LIFTERS Crane 144536-16 INTAKE MANIFOLD Edelbrock (TBA) 650 CFM CARBURETOR Holley 0-82651 Street HP FUEL INLET ASSEMBLY Earl’s AT101185ERL FUEL PRESS. REGULATOR Holley 12-707 FUEL FILTER Earl’s AT230206ERL CARB INSTALL KIT Holley 20-124 THROTTLE BRACKET Holley 20-88 6LS IGNITION CONTROL MSD 6010 EXHAUST HEADERS Flowtech 91836-1FLT LS COIL COVERS Holley 242-1 OIL PAN & PICKUP Holley 302-1 WATER PUMP Tuff Stuff 1310B OLDS/CADDY RETRO AIR CLEANER Speedway Motors 92511925 REAR OIL RESTRICTOR GM 12573460 FRONT OIL GALLEY PLUG GM 09427693 (Note: Complete block completion kit is available from Scoggin-Dickey, P/N SDL SPK. This includes cyl. head dowels, trans. Dowels, all block plugs and oil restrictor)