LSX BH Options

INSTALL AN LSX ENGINE WITH EARLY SMALL-BLOCK COMPONENTS

First, the crankshafts. On the Gen I, the crankshaft flange (i.e. flywheel mounting surface) is .740” past the BH mounting surface on the block. The Gen III comes in at .340”, a difference of .400”. Now there are three small-block crankshaft flange bolt patterns; the Gen I (’55-’86, two-piece rear seal) @ 3.58” dia. / the Gen I (’87-’96, one-piece rear seal) @ 3.00”, and the Gen III (LS / one-piece seal) @ 3.11” dia. (with metric threads). No interchange there...BUT, McLeod sells a “conversion” flywheel for using Gen I components with the LS, part #460535 available from Summit Racing.

Second, the pressure plates. Gen III pressure plates are metric...bolt pattern and fasteners. The Gen III flywheel uses a metric bolt pattern for the pressure plate, and the PP is located by pins, not the bolts. The solution for this is the McLeod flywheel, which makes up the .400” distance differential at the crank, and allows using early SBC pressure plates with 3/8”-16 shouldered bolts. Otherwise, the LS flywheel must be re-drilled, and the difference made up somewhere else, say, the pilot adapter, in order to use Gen I components. On our (944) conversion, if the .400” is not made up, the clutch disc hub will destroy the TT splines...hence the 1” thick LS pilot adapter.

Third, the bellhousings. The Renegade Hybrids SBC / LT1 BH had a depth of 6.375”. A pilot adapter was necessary for the Gen I engines, but at a thickness of .600” (...LS is 1.00” - .600”=.400”). Easy enough. We know already that the bellhousings will bolt up, but what works with what? For the 944, the McLeod flywheel (or a re-drilled & counterbored LS flywheel to allow use of 3/8”-16 shouldered bolts on the PP) , a pilot adapter, and Gen I clutch components, and a QTI scattershield #27011 to clear the 168T flywheel, the Gen III (i.e. LS) swap is getting a lot easier, and cheaper. Keisler makes a “universal” aluminum BH to clear the 168T flywheel, but the downside is it limits clutch components to 10.4” or 10.5”. Not really a big concern, considering the large aftermarket for the SBC clutches and pressure plates. What is of concern is the depth...6.49”...too deep for the 944 TT, by .020”. As far as the QTI BH....they will build what we need, so the flywheel is not an issue if the pilot adapter is used.

Fourth, the throwout bearings. For clearance issues on the 944 conversion, the hydraulic bearing is the way to go. But (for the existing slave cylinder setups), a McLeod adjustable lever operated T/O bearing that corrects linkage issues with the LS / Gen I setup, available from Summit Racing, part# 16505. Another, cheaper solution is the McLeod adjustable ball stud, part# 16908, from Summit Racing. GM also makes a “long” ball stud, non-adjustable, part# 3790556, for 1/3 the price.
Last, the engine plates. Several companies now offer the engine mount adapter plates, some of which include Scoggin-Dickey, TransDapt, Street & Performance, even Edelbrock.


PARTS LIST

NOTE: Only the McLeod flywheel is a true “conversion-ready” item, utilizing a bronze pilot bushing. If using the factory GM LS1 flywheel, it will need to be re-drilled and counterbored, and a 1” pilot adapter must be used.

LSX FLYWHEEL PART NUMBERS
460535 McLeod Conversion Flywheel
12562765 GM LS1 Flywheel

PILOT BEARING ADAPTER

Machined Adapter to utilize 944 roller bearing (McMaster Carr #6202)
* 14MM thick bearing will give more TT contact area

BELLHOUSING OPTIONS

1) Keisler Universal / LS1 Conversion Bellhousing (utilizes SBC 10.5” clutch components
2) Custom QTI Steel Scattershield (bolts directly to 944 TT)
3) GM #12554980 C5 Bellhousing / CNC Adapter Plate, .600” thick

HYDRAULIC T/O BEARING OPTIONS

1) Ram #798-78125 (JEG’S), must use with Richmond style Bearing Retainer #1304027001
2) S10 / Corvette T/O slave assembly, used with C5 BH

CLUTCH / PRESSURE PLATE

QTI and GM #12554980 BH accommodate the 168T flywheel and all 11” clutch assemblies

STARTER

LS1 / factory GM

OTHER PARTS

Additional parts, such as engine mounts, headers, wiring harness, etc. remain the same as with the RH LS1 kit. The only parts that do not have an RH alternative at this time are the headers. Everything else can be sourced through other vendors.