Have you ever seen the comic strip Little Orphan Annie? She was a little red-headed girl who found herself involved in many adventures with mostly unscrupulous adults. So it made sense to call our LS engine the “Little Iron Orphan,” as its adventures will probably be similar. Our engine ended its first life as a corroded, cast-off 5.3L that we inherited with the purchase of Orphan’s 6.0L big sister (“You have to take both engines if you want the 6.0L”).
We decided to stretch the little 5.3L block’s boundaries by expanding the stock bore out to 5.7L dimensions. Since the 5.3L, 5.7L, and 6.0L Gen-III engines all share the same stroke, we could easily build a 5.7L on a budget. However, as often happens with best-of-intention plans, problems arose from the outset.
Our block turned out to be nasty and rusty enough to be untrustworthy. We discovered that Summit Racing could ship a block already bored and honed to 5.7L specs, decked, and fitted with new cam bearings and all-new small parts for less money than it would cost to have our local machine shop do the same work. Plus, the Summit block arrived with free shipping in a matter of a few days. That made the decision easy.
The Short-Buck Short-Block
We’ve never been enthusiastic about the stock LS powdered-metal connecting rods because the fractured cap does not allow easy resizing. We decided to upgrade to a set of pressed-pin, Scat 4340 forged-steel, stock-length rods. We then ordered a set of stock-replacement, standard 5.7L bore (3.898-inch) Speed-Pro hypereutectic pistons and a stock ring set.
Our 5.3L crank was also crusty, so we had our machine shop, JGM, polish it for us. The next stop was to deliver the rotating assembly to our friend, Guy Tripp at SoCal Diesel, to balance the rotating assembly. With information from our friends at Federal-Mogul, we discovered the 5.7L pistons are only 10 grams heavier than the stock 5.3L pistons, so balancing wasn’t an issue. JGM pressed the rods on the pistons for us, and the short-block was ready for assembly.
Stock LS1 pistons employ a 1.5mm/1.5mm/3.0mm ring package, which is thinner than traditional 1/16-inch top rings, and the thinner LS1 oil rings produce less tension as well. If we were building an all-hands-on-deck naturally aspirated LS, we would have stepped up to forged pistons and a thinner 1.0mm ring package. But for this mild street version, the standard 1.5mm package promised to be good and affordable.
We didn’t spend the extra money for 0.005-inch oversize rings, so we just installed the stock-replacement rings on the pistons and used an ARP ring compressor to guide the pistons into the bores.
New cam bearings can sometimes be tight on a new cam, so we installed the Summit cam (see below) before the rotating assembly. That way we could address a cam bearing problem without having to work around the crank and rods. In this case, the cam slid right in place, so drama was averted.
We also ordered a Summit dual-row timing set and spent the extra time to degree the cam to ensure it achieved the proper intake centerline. We ended up with the cam slightly advanced at 107 degrees compared to the Summit cam’s recommended installation of 108 degrees ATDC.
Our experience with used LS truck engines is that previous owners tend to be less-than-casual about oil changes. This abuse to the hydraulic lifters means we consider them scrap in a build. We replaced the stock lifters with a new Summit kit that includes new plastic lifter guides and fasteners as well.
The best way to make power on any engine is to improve breathing. While even stock LS engines are blessed with good flowing heads, stock LS heads can still be improved upon. The best approach would be a pair of TFS cathedral port heads, for example, but these were outside our foster-care budget.
Instead, we talked to Richard Reyman at West Coast Racing Cylinder Heads (WCRCH) in Van Nuys, California. His company offers an affordable porting operation on production 4.8/5.3/5.7L heads which delivers a significant airflow increase.
The big difference between a set of 5.3L (852 or 706) heads and 5.7L LS1 (853) heads is the chamber size and the intake-valve diameter. The 5.3L truck heads use a 1.89-inch intake valve, while the 5.7L heads found on car engines enjoy a 2.00-inch intake valve. We initially planned to use 5.3L heads on our Orphan but the combination of the smaller 61cc chamber and flat top 5.7L piston pushed the compression ratio past 11.0:1, which is too high for California 91-octane pump gas.
Instead, we employed a set of stock 853 heads from an LS1 because they have larger chambers and were cheap and available. We reused the stock 2.00/1.55-inch valves but took advantage of the WCRCH CNC porting work. We also had Reyman deck the head slightly, bring the 67cc factory chambers to 65cc. That increases the compression to 10.5:1 using a set of 0.041-inch thick Fel-Pro MLS head gaskets. We felt that this combination of improved port flow with more compression would push the Orphan 5.7L up to a decent horsepower plateau.
The next step was deciding on a camshaft. With a budget to consider, we discovered Summit recently introduced a line of affordable LS camshafts. We decided to push a little harder than our usual conservative approach and landed on the Pro LS Truck cam.
With 226 degrees of duration at 0.050 on the intake and 230 degrees on the exhaust, both sides feature 0.545-inch lift and a 112-degree lobe separation angle (LSA). This isn’t a wild cam by any means, but with the WCRCH ported heads, we expect the peak horsepower number to be up around 6,300 rpm.
West Coast Racing Port Flow Numbers
These are WCRCH’s numbers for a ported 5.3L head with a 2.00-inch intake valve but should be very close to the 2.00-inch valve 5.7L 853 head we’re using. Stock intake flow numbers on a 5.7L head at 0.500 lift measure around 226 cfm, so this CNC effort is worth around 40 cfm. On the exhaust side, at 0.500, the stock 5.7L port flows 171 cfm so the improvement is a solid 26 cfm. The bore diameter for these WCRCH flowbench numbers used the smaller 5.3L engine’s 3.780-inch bore size, so the numbers from a 3.89-inch 5.7L bore would be slightly better.
|Valve Lift (in.)|| Intake |
| Exhaust |
| Exhaust |
Topping Off the Mash-Up
We topped off the package with an Edelbrock Performer RPM dual-plane intake and a simple 750 HP Holley mechanical-secondary carburetor. This is one of our favorite dyno carbs because they also work very well on the street. The combination would also run almost as strong with a vacuum-secondary carburetor, like a 3310 750 Holley.
We wanted to make sure the Orphan was completely ready to go into a car and that there were no leaks, so we bolted it to our Summit Racing engine test stand, and it was soon ready to make some noise. We pre-filled the oil pump and filter with Lucas 5W-30 performance oil and removed the spark plugs.
Because we had plenty of assembly lube on the bearings, we tried spinning the engine with the starter motor to build pressure. It took about 15 seconds to produce oil pressure on the gauge. We could have pressure-lubed the engine, but truth be told, we were impatient to hear it run.
With the MSD ignition box hooked into the cam and crank sensors and wired to power, a couple of squirts of fuel was all it took for the Orphan to fire up immediately. We kept the RPM up for a few moments and then set the idle speed and mixture screws — the engine sounded great.
We only ran it for about two minutes or so to make sure everything sounded good since it’s best to break the engine in with a load rather than on a test stand. We’ll have to save the break-in for in-car testing unless we can come up with an excuse to run this rascal on the dyno.
The 112-degree LSA helps the idle quality a little, and we later discovered it would still idle at nearly 16 inches of vacuum at 900 rpm. With an automatic trans, that would probably drop to around 15 inches or so because it has to drive the front pump. Still, it makes this engine very streetable and would support a power brake booster with no problem.
Our handy engine power-estimation equation tells us this mild 5.7L LS should make around 450 hp and 440 lb-ft of torque. These aren’t headline-grabbing numbers — but that wasn’t the goal with this engine. The Iron Orphan will likely spend its time in between the fenders of an early El Camino that belongs to a certain MMA heavyweight amateur fighter who is currently winning bouts in Iowa. This motor thumps almost as hard as he does!
Iron Orphan Parts List
|Summit 5.3L iron block to 3.898-inch bore||150157||Summit Racing|
|Summit Racing LS Truck camshaft||8714||Summit Racing|
|Summit valve spring kit||TFS-16918||Summit Racing|
|Summit valve lifter guide kit||SUM-HTLSKIT||Summit Racing|
|Summit timing set, billet steel||G6602R-B||Summit Racing|
|Summit rocker trunion upgrade kit||SME-143002||Summit Racing|
|Summit trunion install tool||141560-IK||Summit Racing|
|Speed-Pro 5.7L hypereutectic pistons||H868CP||Summit Racing|
|Speed-Pro piston rings, std bore 5.7L||R-1060||Summit Racing|
|Scat LS1 press-pin connecting rods||ICR6100-944P||Summit Racing|
|Speed-Pro performance rod bearings||8-7100CH 1||Summit Racing|
|Speed-Pro performance main bearings||152M 1||Summit Racing|
|Federal-Mogul standard oil pump||22443645||Summit Racing|
|Fel-Pro thin head gasket 041 Left||1160-041L||Summit Racing|
|Fel-Pro thin head gasket 041 Right||1160-041R||Summit Racing|
|Edelbrock Performer RPM intake||71187||Summit Racing|
|Holley 750 cfm HP carburetor||0-80528-1||Summit Racing|
|Sealed Power full gasket set||2601880||RockAuto|
|Fel-Pro intake gasket for carb manifold||1312-1||Summit Racing|
|Fel-Pro header gasket||1438||Summit Racing|
|ARP head bolts, early version||134-3609||Summit Racing|
|MSD ignition box||6014||Summit Racing|
|Pushrods, TFS 7..400-inch||TFS-21407400||Summit Racing|
|Holley retro-fit cast oil pan||302-2||Summit Racing|
|Lucas 5w30 oil||10474||Summit Racing|
|Fram oil filter, Extended Life||TG3675||Summit Racing|
|ARP digital rod bolt stretch gauge||100-9943||Summit Racing|