RETRO LS, PART 5

 

THE FINAL ASSEMBLY

 

by Mike Mavrigian

Our intent with this build is to illustrate how you can take advantage of current LS (mechanical) technology, and still create a somewhat old school traditional appearance, grabbing in the range of 450 HP, all without breaking the bank. In terms of exterior finish, we intentionally “relaxed” our normal attention to visual detail, in an effort to somewhat simulate what the factory might have produced on a production line (we suppressed our urge to dress the surfaces). As a result, we did not take the time to smooth out the casting exterior surfaces (opting not to eliminate casting flashings or polishing out uneven surfaces). Paint-wise, we followed the same approach. We purposefully did not attempt to create a show finish.

The block, heads, intake manifold, valve covers, coil covers, top valley plate and water pump were squirted with “vintage” Chevy orange.

 

In this final-assembly article, we’ll cover our intake manifold, carburetor, water pump, exhaust headers, our custom coil pack covers and out MSD ignition controller.

 

INTAKE MANIFOLD

Since we intended to use a 4-bbl carb, we opted for Edelbrock’s dual-plane performer Air Gap manifold, P/N 71187. This is intended for use with various LS applications that feature cathedral intake ports. The advertised torque curve is 1500-6500 rpm. After trial-fitting and checking port alignment (we performed a bit of port correction to perfectly match the cylinder head ports), we painted the manifold using a high-build primer, intentionally applying a bit of a stippled buildup to mimic an OE cast manifold, then coated her with good ol’ Chevy orange. The manifold is secured with new OE GM 8mm bolts.  As when installing any aluminum intake manifold, it’s imperative to follow the correct tightening pattern and torque specs to avoid vacuum leaks.

Note: While the OE torque spec for an original intake manifold is listed at 44 in-lb (first pass), followed by 44 in-lb, we followed Edelbrock’s specs, which call for tightening the intake manifold bolts to a final value of 11 ft-lb (132 in-lb).

 

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In order to “convert” our 327 CID LS engine to carburetion, we obtained an Edelbrock Performer Air Gap aluminum manifold, P/N 71187. In an effort to achieve an old-school OE appearance, we prepped the surface and painted with good ‘ol Chevy orange.

 

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Intake gaskets feature formed silicone bead seals. We applied a light coat of gasket cinch to secure the gaskets in place during manifold placement.

 

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We tightened the intake manifold bolts to Edelbrock’s recommendation of 22 ft-lb, following the correct tightening pattern.

 

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Shown here is the manifold bolt tightening sequence. This spreads out the clamping force to optimize sealing (illustration taken from Edelbrock’s instructions).

 

 

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CARB

To feed our 327 CID puppy, we chose a 650 cfm Holley Street HP (P/N 0-82651), fed by a –6 Earls plumbing dual inlet assembly (with black anodized fittings for an understated appearance), along with a Holley pressure regulator (12-707), Earls filter AT230206ERL, Holley carb install kit 20-124 and Holley throttle bracket kit 20-88. The carb is secured to the manifold with 5/16” studs/washers/hex nuts.

 

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This Holley 650 cfm Street HP carb (P/N 0-82651) was chosen as an ideal size for the 327 CID application.

 

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Our Earls fuel inlet features a -6 feed and stealthy black anodized fittings. The long standoffs provide great clearance.

 

 

WATER PUMP

Instead of using a stock GM water pump, we opted for a polished aluminum direct-replacement pump from Tuff Stuff. While their in-house polishing looked totally cool, we wanted the pump to “blend in” with our OE theme, so we painted it in Chevy orange. The Tuff Stuff pump is a brand new unit (actually made by Tuff Stuff in-house) and features heavy duty impeller and bearings, and the outer surface is MUCH smoother and less “raw” looking than the OE pump. As expected (and based on our previous experience with Tuff Stuff components, the pump fit perfectly, and pulley offset was right on the money. Water pump mounting bolts were tightened to a value of 11 ft-lb (first pass), followed by a final value of 22 ft-lb.

We then installed a new GM aluminum thermostat and housing to the water pump’s thermostat port. The housing (including thermostat) is available as GM P/N 12600172. The formed seal is available as GM P/N 12570307.

 

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The Tuff Stuff water pump featured a polished aluminum body and a chrome plates pulley. This isn’t a cheapo rebuild, by the way. Tuff Stuff actually makes their own new pumps.

 

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Here we test fit the Tuff Stuff water pump prior to prep and paint.

 

 

Tuff Stuff’s polished finish was very pretty, but we decided to paint the pump orange to lend an “original” old scool appearance.

 

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The thermostat housing, seal and thermostat are available from any GM dealer.

 

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When installing the thermostat to the housing, note that the seal features a locating tab that must seat into the notch in the housing.

 

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The Tuff Stuff water pump pulley provided an ideal belt alignment.

 

 

 

HEADERS

Since most hot rodders running a vintage smallblock would normally toss their iron manifolds and slap on a set of tubular exhaust headers, we installed a set of ceramic coated Flowtech block hugger shorties. These fit like a glove to the LS heads (no need to tweak the flanges or enlarge bolt holes).  The one-piece precision-cut exhaust flange provided perfect hole line-up. Using direct-replacement OE-style beaded stainless exhaust gaskets from our Mahle Victor gasket set, we anchored the headers with a set of ARP polished stainless steel 8mm studs, washers and 12-point nuts. The use of these ARP studs not only improves appearance, but provides a guide and “hanging” point when installing the gaskets and headers. We snugged all header flange nuts to 18 ft-lbs.

 

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The Flowtech exhaust headers, P/N 91836-1FLT, feature a very attractive and definitely-durable ceramic coating, in a high-lustre finish. Just bolt ‘em on and go.

 

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We installed ARP polished 8mm stainless steel studs to the cylinder heads for exhaust mounting. The studs feature a handy female hex for easy installation/removal. We installed formed stainless steel exhaust gaskets from our Mahle Victor gasket set.

 

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Left side exhaust header. The block hugger design fit the LS perfectly. Flange holes offered spot-on alignment to the cylinder heads and clearance to the block was tailor-made.

 

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Right side view. Both sides provided excellent spark plug wire clearance as well. We literally made no mods to the headers at all. They dropped right on with no fuss.

 

 

 

COIL COVERS

As we all know, the LS engine family features a row of four individual coils mounted onto each valve cover (stock locations). Appearance-wise, we have several choices. We can install pretty red MSD coils and nix any type of cover, or if you prefer to hide the coilpacks (and their wiring harness), Holley, Edelbrock, Katech and others offer composite covers that snap onto the OE valve covers. Another option is to re-locate the coils. This can be done by a number of means, including mounting the coils on the firewall or inner fender areas, or mounting them at the front of the engine on a fabricated mounting bracket. In this particular case, we decided to leave the coils in their OE location (on the valve covers), and hide them with custom covers.

We started with a pair of  Holley’s coil covers, which (when painted to the color of your choice) do a great job of not only hiding the coil packs, but create the outward appearance of a bigblock Chevy engine (the covers are nice and fat). They’re made of high impact ABS and are easy to prime and paint. They also features studs that snap into the OE coil cover holes in the stock valve covers, for easy on/off service. They’re easy to paint, easy to install, and they vastly improve the appearance.

As nice as the Holley covers are, we decided to create something totally custom (because we’re sick puppies and can’t resist playing). We made a male pattern, followed by making a mold, and popped out a pair of fiberglass covers that feature the old-school raised rib at the center (front to rear), with front and rear ends radiused to simulate early-1960s stamped steel OE valve covers. Oval holes were cut on the outer walls for spark plug wire pass-through.

The covers were painted in traditional Chevy orange. That provided us with a “vintage stock” look as our basis. For an added custom touch, we installed 0.032”-thick carbon fiber rectangular panels, finishing by adorning the tops with chromed cast metal Chevrolet-script body emblems. We then fabricated adapter plates to our custom coil cover brackets that allowed us to secure the covers using duo-lock (mushroom head) strips (similar to Velcro in terms of use but much more secure, since the strips snap together). The result was stunning (at least we think so). The covers convey a retro appearance, with a touch of custom flavor. This is merely one example of the possibilities when you want to cover up those busy-looking coils and their harnesses. If you want to take the easy way out though, I’d highly recommend the Holley coil covers. Simply paint (or plate) and they’re ready to go.

 

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Holley’s coil pack covers offer an excellent method of hiding the coil packs while achieving a tidy “big block” appearance. Just paint ‘em and snap ‘em on.

 

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The Holley coil covers feature handy female receptacles that snap onto bare-shank studs on the valve covers. Installation couldn’t be easier. This is a very well thought-out design.

 

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Here we test fit a Holley coil cover. The inboard cutouts accommodate the coil wiring harness.

 

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In this photo, we mocked up the long block with a pair of Holley’s coil covers. It’s apparent that these covers create a larger “bigblock” appearance.

 

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Our custom-made coil covers feature a center raised rib and are painted in Chevy orange (our simple approach to create more of an “old school” look.  Since we couldn’t leave well enough alone, we then added a thin carbon fiber accent panel and then installed a chromed Chevy script (body emblem) on top of the carbon panel. We also made oval ports for passage of the spark plug wires to the coils.

 

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OK, so the carbon fiber isn’t OE-looking, but we thought it was a cool touch.

 

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The spark plug wires can be removed/installed to/from the coils without removing the covers. You’ll have to excuse the somewhat flat paint finish in this photo. We later wet-sanded and buffed the covers for a better finish.

 

 

 

AIR CLEANER

To represent what an old-school hot rodder may have chosen, we selected a very vintage-looking dual-inlet Caddy style air cleaner assembly (from Speedway Motors). The only mod we made was to create and install a “factory”-looking engine identification decal.

We made our own air cleaner decal using ink-jet chrome film (with glue applied to the surface so that the ink adheres to the top surface, with a peel-away adhesive backing). The design was created in AutoCad and printed out on an ink jet printer. After the ink dries, a thin clearcoat was applied to seal the ink. We duplicated the arc of the design used by GM on 1960s air cleaners.

The design includes “327” at the top (since we overbored to create 327 cubic inches of displacement), followed by “TURBO-FIRE” as the second line, followed by “450 HORSEPOWER” as the bottom line (kinda OE looking).

Since the decal featured a paper-based backside, it needed to be installed dry (since liquid would damage the paper-structure adhesive side), so careful measuring and reference marking with masking tape was needed in order to insure correct placement (once it’s stuck, it’s stuck).

 

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The very vintage-looking Caddy air cleaner assembly from Speedway Motors definitely lends a nostalgic look.

 

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Since we couldn’t find an original-style air cleaner decal that said what we wanted, we made our own decal using an AutoCad program. After printing it out and trimming, we applied a thin clearcoat to protect and seal the ink, prior to installation.

 

 

 

 

 

IGNITION

Since we’re running a carb instead of fuel injection (and no ECU), we needed a way to fire the coil packs. This is so simple that it’s almost embarrassing. All you need is an MSD 6AL ignition module, an MSD wiring harness and a few OE engine sensors (cam sensor, crank sensor and coolant temp sensor). The MSD ignition module is fully adjustable by either plugging in one of the pre-programmed “chips” or by custom-tailoring the ignition curve using the supplied software CD, using a laptop or desktop PC. The MSD ignition module can be mounted on the intake manifold or remotely mounted wherever you want (engine bay or interior). When you order the ignition box, you need to specify which reluctor wheel is present on the crankshaft (24-tooth or 58-tooth). Our crank features a 24-tooth reluctor wheel. The ignition module must be matched to the tooth count for proper timing control.

We ran Bosch Iridium spark plugs P/N 9602 and Bosch 7mm Ultra-Premium Opti-Layer Mag Core spark plug wires to connect to the coils.

 

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Bosch Iridium spark plugs provide a strong and reliable spark for our little 327.

 

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Bosch 7mm Ultra Premium Mag-Core wires are pre-assembled for direct replacement fit to an LS engine.

 

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MSD offers their 6LS ignition module and a complete ignition wire harness to make converting an LS engine to a carbureted version easy as pie. No ECU is needed.

 

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The 6LS ignition module includes an array of six pre-programmed plug-in “chips,” each with its own ignition curve. The instruction manual clearly describes each setting. If you prefer to map your own curve, software (CD) is included. This allows you to create your own curve using a PC or laptop (it’s not as difficult as you might think).

 

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Just for the heck of it, here’s a shot with an OE water pump (painted). The Tuff Stuff pump looks way cooler.

 

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TORQUE VALUES (relating to this article)

Intake manifold bolts (Edelbrock)…………..11 ft-lb

Water pump bolts……………………………11 ft-lb followed by 22 ft-lb

Exhaust header to head………………………18 ft-lb

Ignition coils to coil brackets………………..106 in-lb

Coil brackets to valve covers………………..106 in-lb

Spark plugs (w/anti-seize)……………………15 ft-lb (new); 11 ft-lb afterwards)

 

(refer to previous articles in this series for additional engine fastener torque specifications)

OUR REPLACEMENT PARTS LIST

 

ITEM                                                MFG                                    PART NO.

 

PISTONS                                 Sealed Power                         H1132CT (+ 0.25mm)

 

PISTON RINGS                         Hastings                               2M4978010

 

CONN. RODS                           GM                                        12577583

 

MAIN BEARINGS                   Mahle-Clevite                       MS-2199H

 

ROD BEARINGS                      Mahle-Clevite                       CB663A

 

CAM BEARINGS                     Mahle-Clevite                       SH18145

 

GASKET 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                      71187

 

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

 

OIL FILTER                                 AC DELCO                       PF48

 

DIPSTICK & TUBE                     Mr. Gasket                        6239

 

WATER PUMP                            Tuff Stuff                           1310B

 

OLDS/CADDY RETRO

AIR CLEANER                           Speedway Motors                 92511925

 

REAR OIL RESTRICTOR          GM                                        12573460

 

FRONT OIL GALLEY PLUG     GM                                        09427693

 

SPARK PLUGS                         Bosch                                       9602

 

SPARK PLUG WIRES              Bosch                                       09449

 

CUSTOM COIL COVERS        Birchwood Automotive    (fabricated prototypes)

 

THERMOSTAT HOUSING      GM                                          12600172

THERMOSTAT SEAL              GM                                          12570307

 

 

(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)

 

 

 

 

 

 

 

 

 

 

 

 

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  • Glenmpe

    yea plug wires look like they clear by a mile! and by the looks of the intake having the reciever grooves 4 the gasket they should have been glued to the intake not the flat head surface. thats the guys i want to build my engine alright.

  • Larry

    A Holley Avenger Fuel injection system could be a cool upgrade someday ! 

  • Kent

    Any dyno numbers on this beauty?