Mike Mavrigian [email protected]Performance Perspectives 22 September 2009 Y ou face a few choices with regard to fuel, air and ignition when building a GM LS engine. You can stick with the OE fuel injec- tion like everyone else, install an expensive aftermarket perfor- mance fuel injection system or convert to a carburetor setup. If you plan to use a carb in- stead of fuel injection, you also have a choice of ignition setups, which involves either using the eight individual coilpacks and a timing controller or going to a front-mount distribu- tor (with built-in HEI coil) and eliminating the eight coilpacks. Here, we’ll address both carb approaches. I built an LS2 engine with a carb and coilpack setup, so I’ll refer to that specific build as one example. Carb Setup If you prefer to run a carburetor, you have a choice of two formats. One option involves the use of a four-barrel intake manifold, a carbu- retor, a distributor adapter and a distributor. A typical setup might include an Edelbrock Vic- tor Jr. intake manifold (Part No. 29087) or the Super Victor Jr. intake manifold (Part No. 28097), a GM distributor adapter (Part No. 88958679), a Performance Distributors Ford small-block distributor (Part No. 31820) and Performance Distributors plug wires (Part No. C9076). The GM adapter serves as a timing cover, taking the place of the original cover, and fea- tures a housing that accepts the Ford small- block distributor. A short camshaft stub with distributor gear (part of the adapter set) bolts to the existing camshaft, providing a means to drive the distributor. A second (less expensive and more readily available) option might include the Edelbrock Victor Jr. or Super Victor Jr. intake manifold with the stock-type timing cover, no distribu- tor, eight coilpacks and an MSD timing con- trol module (Part No. 6010). The module uses signals from both cam and crank timing sen- sors. (Other setups are also available—for ex- ample, a Victor Jr. intake manifold can be drilled to accept fuel injectors. Instead of a conventional carb, a downdraft throttle body is used to regulate the intake air.) For those hot rodders who prefer ‘old school’ carb setups on the current generation of small-block and big-block GM engines, swapping to a carb is easier than you might think. Photos: Mike Mavrigian The Edelbrock Super Victor Jr. intake manifold is a single- plane high-rise unit that accepts a square-bore four- barrel carb, with an operating range up to 8000 rpm. The carb I used for my LS2 build is Edelbrock’s Per- former, which features a healthy 800 cfm. Edelbrock recommends this carb to be used on an LS engine that features more than 6.0 liters of displacement. continued on page 24
You face a few choices with regardto fuel, air and ignition whenbuilding a GM LS engine. Youcan stick with the OE fuel injec-tion like everyone else, install anexpensive aftermarket perfor-
mance fuel injection system or convert to acarburetor setup. If you plan to use a carb in-stead of fuel injection, you also have a choiceof ignition setups, which involves either usingthe eight individual coilpacks and a timingcontroller or going to a front-mount distribu-tor (with built-in HEI coil) and eliminatingthe eight coilpacks. Here, we’ll address bothcarb approaches. I built an LS2 engine with acarb and coilpack setup, so I’ll refer to thatspecific build as one example.
Carb SetupIf you prefer to run a carburetor, you have achoice of two formats. One option involves theuse of a four-barrel intake manifold, a carbu-retor, a distributor adapter and a distributor. Atypical setup might include an Edelbrock Vic-tor Jr. intake manifold (Part No. 29087) or the
Super Victor Jr. intake manifold (Part No.28097), a GM distributor adapter (Part No.88958679), a Performance Distributors Fordsmall-block distributor (Part No. 31820) andPerformance Distributors plug wires (Part No.C9076).
The GM adapter serves as a timing cover,taking the place of the original cover, and fea-tures a housing that accepts the Ford small-block distributor. A short camshaft stub withdistributor gear (part of the adapter set) boltsto the existing camshaft, providing a means todrive the distributor.
A second (less expensive and more readilyavailable) option might include the EdelbrockVictor Jr. or Super Victor Jr. intake manifoldwith the stock-type timing cover, no distribu-tor, eight coilpacks and an MSD timing con-trol module (Part No. 6010). The module usessignals from both cam and crank timing sen-sors. (Other setups are also available—for ex-ample, a Victor Jr. intake manifold can bedrilled to accept fuel injectors. Instead of aconventional carb, a downdraft throttle bodyis used to regulate the intake air.)
For those hot rodders who prefer ‘old school’ carb setups on
the current generation of small-block and big-block GM
engines, swapping to a carb is easier than you might think.
Phot
os: M
ike
Mav
rigi
an
The Edelbrock Super Victor Jr. intake manifold is a single-plane high-rise unit that accepts a square-bore four-barrel carb, with an operating range up to 8000 rpm.
The carb I used for my LS2 build is Edelbrock’s Per-former, which features a healthy 800 cfm. Edelbrockrecommends this carb to be used on an LS engine thatfeatures more than 6.0 liters of displacement.
continued on page 24
Performance Perspectives
mounting bolts than are providedwith the manifold. The bolts pack-aged with the manifold are6x1.0x50mm. If you use the plasticbody gaskets, you’ll need bolts with ashank length of 55 to 60mm.
24 September 2009
First, let’s address mounting thecarbureted intake manifold, citing theEdelbrock Super Victor Jr. While youcan use an OE plastic-type intakemanifold gasket set (the gasket bodyis .200 in. thick), you’ll need longer
The Edelbrock instructions specifi-cally say to use Fel-Pro Part No.1312-3 gaskets, which are .063 in.thick. While the provided bolt lengthof 50mm is fine, I ran into an inter-ference issue when using the thinnerFel-Pro gaskets, between the bottominboard surface of the intake runnersand the engine’s top valley coverplate. The runners hit the outer edgeof the plate, preventing full mating ofthe manifold decks to the heads. Thesolution would be to either grind re-liefs on the inboard bottom of therunners or to chamfer the edges ofthe valley plate. I opted for the latter.With the manifold mocked in place, Imarked the cut areas on the valleycover for each of the eight cuts. Iwould have preferred simply cham-fering the entire length of each sideof the cover plate, but the chamferswould have interfered with the mani-fold bolt washer footprints. Using aBridgeport mill, Jeff Lance at Alan-M&S Machine (Wadsworth, OH) cuteight chamfer reliefs on the top edgeof both the right and left sides of thevalley plate.
Once this interference issue hadbeen resolved, I torqued the intakemanifold bolts to a value of 11 ft.-lbs.per Edelbrock’s instructions and fol-lowed the recommended bolt-tight-ening sequence. The Edelbrock Per-former four-barrel carb (Part No.1412) was snugged to the intake to 90in.-lbs. using ARP stainless-steel carbstuds and nuts.
The Edelbrock Super Victor Jr.carbureted intake manifold featuresan operating range of 3500 to 8000rpm. This is a high-rise single-planeintake capable of supporting over 600hp. This manifold accepts a square-bore carb. The Super Victor offersgreater airflow potential than previ-ous LS manifolds. The carb mountpad is 1.12 in. taller than the VictorJr. LS1, and the port exits have beenincreased to 1.08x2.74 in. This mani-fold has already been accepted byNASCAR for use in the Grand Na-tional division/Busch North spec en-gine series. Carb pad height is 6.07in.
Edelbrock recommends its Per-Circle #18
former Series Part No. 1412 carb(800 cfm, manual choke) for displace-ments greater than 6.0 liters and/orvehicles that will experience frequenttrack use. Its recommendation for a6.0-liter street application is eitherthe Performer Series Part No. 1407(750 cfm, manual choke) or 1411(750 cfm, electric choke).
Controlling Carb SetupIgnition (With Coilpacks)With regard to ignition control, toutilize a carb with coilpacks and nodistributor on the LS, the MSD Tim-ing Control module is required. Thekit includes the ignition controller,Pro-Data+ software (on a mini CD),wiring harness and individual plug-intiming modules. Optional accessoriesinclude MSD’s hand-held monitor(Part No. 7550) and a wiring harnessfor intake manifold mounting (if youopt to mount the box there).
Note: With a carburetor setup, youneed only the MSD timing controllerkit and coilpacks, an OEM coilpackwiring harness, the crank sensor, camsensor and optional MAP sensor. Youdo not need an ECU. If you’re usingthis MSD timing controller with anEFI setup, then you do need to re-tain an ECU. So, you can use a car-bureted LS engine in any vehicle(street rod, race car, etc.), with noneed for a central ECU.
MSD’s 6010 ignition controller isdesigned for GM Gen III enginesthat have been retrofitted with a car-buretor and carb manifold. The con-troller can also be used in stock EFIapplications by using harness PartNo. 8886.
The controller is supplied with awiring harness that connects to thefactory connectors. A shorter harness,mentioned above, is designed formounting the controller on the intakemanifold, under Part No. 60101.
The MSD controller offers severalprogrammable features that allowrpm and timing adjustments. Thiscan be achieved by using the suppliedPro-Data+ software (and connectinga PC to the controller with the sup-plied PC harness), or with the option-al MSD hand-held programmer
7550. Timing adjustments and selec-tions can also be made by using thesupplied plug-in modules.
The controller kit is supplied withsix timing curve modules that plug in-to a port on the side of the controller.
25September 2009
The modules are labeled Curve 1,Curve 2, etc. By using one of thesemodules, the timing will be set with apreprogrammed curve that wasmapped out by the MSD engineers,tailored for different camshafts, final
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drive gearing and vehicle weight. Soyou can plug in a curve module ofyour choice, or you can create yourown custom program by using thePro-Data+ software and a PC.
You should know that any updatesmade using the PC software will beoverridden if a plug-in module is leftplugged in during power-up of thecontroller. So if you plan to createyour own program, don’t leave amodule plugged in.
The controller allows you to pro-gram two rev limits—one for anoverrev safety and another that pro-vides a low limit for use as a holeshot or two-step limit. The RevLo isthe low rpm limit designed to beused while staging at the startingline. It’s activated when the blue wireis connected to 12 volts. When 12volts are not present on this wire, theRevHi limit is active. It’s adjustablein 100-rpm increments from 2000 to12,500 rpm.
The RevHi is the overrev rpm lim-it. It’s active whenever the blue wire(RevLo) is not connected to 12 volts.
A step retard (Sw retard) will pro-vide an adjustable amount of retardat a specific moment. This is idealwhen using nitrous oxide injection.The amount of retard is adjustablefrom 0° to 15°, in 1° increments. Theretard is activated when the pinkwire is switched to 12 volts. The de-fault retard is 10°.
The programmable instructionsactually are not that complicated.The MSD software walks youthrough it, and rest assured that youdon’t need to be a computer whiz tohandle it. You can program the con-troller at your office desk (it connectsto your PC via the supplied cable), oryou can use a laptop computer whilethe engine is on the dyno or whileyou’re in the car. You can easily cre-ate your own custom timing curve (areally cool advance chart and timingmap appears on the computerscreen), and you can reprogram anytime you want.
The controller instructions alsoclearly list the purpose of each har-ness wire. This makes troubleshoot-ing easier, and allows you to make up
a custom harness if you so desire.Wire identification is provided forthe crankshaft sensor, camshaft sen-sor, optional MAP sensor and coilconnectors (for each cylinder).
The MSD controller box may bemounted in any convenient locationunderhood (firewall, inner fender,etc.), as long as it’s placed away fromhigh-heat sources. It also can be di-rectly mounted to the right rear sideof the intake manifold itself (MSDoffers a mounting bracket for thispurpose, as well as a short wiringharness). Or, for those who prefer tobe different, it could be mounted inthe vehicle interior.
Carb With Distributor(No Coilpacks)The next carb-type setup involves thesame intake manifold and carburetor,but with a twist: Get rid of the eightindividual coilpacks and mount a dis-tributor at the front of the engine.GM Performance offers a distributoradapter kit (Part No. 88958679) thatincludes a cast-aluminum LS frontdistributor drive cover (which re-places the OE front cover) designedto accept a Ford small-block distrib-utor. The kit also includes a stubbycamshaft front extension that bolts tothe existing cam, to provide a drivegear for the distributor.
Performance Distributors offers aFord small-block distributor alreadyfitted with an HEI coil. Remove theOE front cover, install the GM camadapter and cover, drop the distribu-tor in, set your timing and go. Nocomputer, no timing module—just acarb and an electronic distributor.Performance Distributors even offersa ready-to-install set of spark plugwires for this setup. By the way, thedistributor housing also provides amounting location for a mechanicalfuel pump, to the engine-right of thedistributor.
Since the distributor housing is,well, large, it’s obvious that the OE-design water pump won’t fit any-more. Wegner Motorsports, in coop-eration with Stewart, makes a uniqueLS water pump that’s designed towork with this setup. In outward ap-
pearance, it vaguely resembles anOE-style pump with longer legs toclear the distributor housing. In addi-tion, because the water pump pulleynow sticks out further from the block,you’ll also need a special pulley sys-tem (also available from Wegner).
While completing this article, Ilearned that the distributor adapterkit is actually made by Wegner forGM, so apparently you can buy onedirect from Wegner. Had I onlyknown. Because of the added cost inexecuting a carb/distributor conver-sion, you really have to want this set-up to justify the expense.
A Sample Build:Carb & CoilpacksI recently built an LS2 engine with acarburetor setup. My build featured anew LS2 (6.0L) aluminum block, pur-chased from Scoggin Dickey, a well-known GM performance parts stock-ing dealer. The block was then over-
bored by a mere .005 in. (to 4.005 in.),and a Lunati 4.000-in. stroker crankand Lunati 6.125-in. H-beam con-
necting rods were employed toachieve a final displacement of403.13 CID.
The remainder of the build in-volved a pair of Trick Flow aluminumheads, a custom-grind roller camfrom Crane (.624-in. valve lift and256°/264° duration at .050 in.), off-the-shelf JE pistons (our compressionratio was 10.6:1), Harland Sharp alu-minum roller rockers and the Edel-brock Super Victor intake manifoldand Edelbrock 800-cfm carb.
The ignition consisted of MSD coilpacks an MSD timing control mod-ule. On the engine dyno, the motoreasily pulled a documented 625.4 hpand 534 ft.-lbs. of torque withoutbreaking a sweat. Throttle responsewas incredibly quick. The result: anon-computer-controlled lightweightV8 that can shatter glass on down-town high-rise office buildings andsnap your neck under wide-openthrottle. Not bad for “old school.”
27September 2009
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My coilpacks (which can be used ei-ther with EFI or distributorless car-buretor setups) are MSD No. 8245coils. Eight coils are used, with onecoil dedicated to each spark plug.The coils deliver up to three timesthe spark energy of stock coils, andmultiple sparks as well. Maximumvoltage is 44,000 volts, primary re-sistance a mere .570 ohm.
