Edelbrock 61905 User manual
©2012 Edelbrock LLC
Brochure #63-0158Page 1 of 2
Catalog #61905, 61919
Rev..11/09/12 - QT/mc
PLEASE study these instructions carefully before beginning this installation. Most installations can be accomplished with common tools and
procedures. However, you should be familiar with and comfortable working on your vehicle. If you do not feel comfortable performing this installation,
it is recommended to have the installation completed by a qualified mechanic. If you have any questions, please call our Technical Hotline at:
1-800-416-8628, 7:00 am - 5:00 pm, Pacific Standard Time, Monday through Friday.
IMPORTANT NOTE: Proper installation is the responsibility of the installer. Improper installation
will void your warranty and may result in poor performance and engine or vehicle damage.
DESCRIPTION: Edelbrock Performer LT-1 cylinder heads are designed for street/high performance use on LT-1, 5.7L, Small block Chevrolet engines.
They also replace original equipment on 1992 through 1997 LT-1 5.7L equipped vehicles (C.A.R.B. E.O. Call Edelbrock for detailed information).
Edelbrock LT-1 heads feature high velocity 170cc intake ports, 70cc exhaust ports and 54cc combustion chambers. Complete heads come assembled
with valvetrain parts capable of operating up to 6500 rpm. Higher rpm applications will require the use of suitable valvetrain parts like larger valve
springs and retainers. Other outstanding features include phosphor-bronze valve guides, ductile iron valve seats and premium one-piece stainless
steel high-flow 1.940” intake and 1.550” exhaust valves, heat-treated machined steel retainers, valve locks, rocker studs and hardened washers, along
with heavy duty valve springs which work with cams having valve lifts up to .600”. Spring load at .600” lift is 420 lbs. Check camshaft manufacturer’s
spring load specifications when using other than Edelbrock camshafts. These powerful heads use the stock location for intake and exhaust flanges and
bolt holes, and centerbolt valve cover rails for compatibility with original equipment and aftermarket parts. Bolt holes for exhaust and intake flanges
and rocker studs are fitted with helicoil inserts for increased strength. LT-1 heads are available either bare or complete.
Complete cylinder heads are assembled using the following components:
• Stainlesssteel,one-piece,swirl-polishedintakeandexhaustvalveswithunder-cutstemsforincreasedflow
• Rockerstudsandhardenedwashersforusewithself-aligningrockerarms
• Highqualityvittonlipsealswithmetaljacket
• EdelbrockSure-Seatvalvesprings#5845
• Retainers#9724
• Valvekeepers#9616
• Valvespringseats#5769
Complete cylinder heads are assembled and prepared for trouble-free installation right out of the box. Bare cylinder heads will have valve guides
and seats installed, but will require final sizing of the valve guides and a valve job to match the valves you will be using.
Hardware & Parts Required for Installation
For a successful installation, the Edelbrock Performer Cylinder Heads require some components other than original equipment parts. To complete your
installation, you will need the following items:
q Headgaskets;GM#10168457orFel-Pro#1074orequivalent.
q Intake manifold gaskets; GM# 12367777 or Fel-Pro #1284 (Will
require port matching).
q Exhaustgaskets;Fel-Pro#1404orequivalent.
q Edelbrockheadboltkit#8550;(seeinstructionsbelow).
PERFORMER LT-1 CYLINDER HEADS
For 1992-1997 Chevrolet LT-1 Engines
Catalog #61905 (Complete), #61919 (Bare)
INSTALLATION INSTRUCTIONS
®
q 14mmx3/4”reachgasketedsparkplugs,ChampionRC-12YCor
equivalent.
qPushrods; .100” longer-than-stock, hardened preferred (if using
stock type rocker arms)
q Self-aligning rocker arms - GM #12495490 (stamped steel
1.5:1 ratio); GM #12370838 (aluminum roller, 1.5:1 ratio); & GM
#12370839(aluminumroller1.6:1ratio)orequivalent.
CHECKING PISTON-TO-VALVE, PISTON-TO-BORE AND PISTON-TO-HEAD CLEARANCES: Prior to installation, it is highly recommended that valve-
to-piston clearances are checked and corrected to minimum specs, if necessary. A minimum of 0.100” clearance is recommended for both intake
and exhaust. If other than stock valve sizes are used, they may not work with the valve pockets in stock pistons, especially if a high lift cam is used.
The use of aftermarket pistons and/or custom machining to your pistons may be required. Actual valve-to-piston clearance should be specified by
your camshaft manufacturer. If these cylinder heads are used on small bore engines, valve-to-bore clearance should also be checked, and the top of
the bore notched for clearance, if necessary.
ACCESSORIES: Although Edelbrock Performer LT-1 Heads will accept OEM components (valve covers, intake manifold, etc.), we highly recommend
that premium quality hardware be used with your new heads:
©2012 Edelbrock LLC
Brochure #63-0158Page 2 of 2
Catalog #61905, 61919
Rev..11/09/12 - QT/mc
Fig. 1 - Cylinder Head Tightening Sequence
SPECIFICATIONS
Head Bolt Torque: ...................... 65 ft./lbs. (in steps of 40, 55, 70)
Rocker Stud Torque: ...................................................... 45 ft./lbs.
CombustionChamberVolume:.............................................. 54 cc
Deck Thickness: .................................................................... 5/8”
ValveSeats: ......... Hardened ductile iron, compatible with any fuel
ValveSize: ............................................ (PN 61909) Intake 1.940”,
...............................................................................Exhaust 1.550”
ValveSpringDiameter: ....................................................... 1.450”
ValveSpringInstalledHeight:.............................................1.800”
ValveSpringSeatPressure: ...............................150lbs.@1.800”
..........................................................................420 lbs. @ 1.200”
Max.ValveLift: ..................................................................... .600”
Head Bolts or Studs: High quality head studs or head bolts with hardened washers must be used to prevent galling of the aluminum
boltbosses.Edelbrockheadboltkit#8550includesallboltswhichmustbeusedwiththesecylinderheads.Stockheadboltsmaybeusedifthey
meetthesespecsforlength:1-3/4”(shortbolts);3”(mediumbolts);3-13/16”(longbolts).Boltsnotmeetingthesespecsdonothaveenough
threadengagementforusewithhardenedwashers.TherecommendedhardenedwashersareGM#10051155,ARP#200-8511,orequivalent.
Rocker Arms and Valve Train: Stock (stamped type) rockers may require +.100” longer-than-stock pushrods (hardened preferred) to maintain
proper geometry. The valve springs supplied will accommodate valve lifts up to .600”, which is much higher than stock rocker arms will allow.
Longslotstampedorrollerrockerarmswillberequiredifyourcamshafthasmorethan.480”lift.
CAUTION: GM LT-1 heads are factory-equipped with “self-aligning” rocker arms. These rocker arms have a stamped recess on the valve
tip end to guide the rocker arm on the valve stem which allows the rocker arm to guide the pushrod. Edelbrock Performer LT-1 PN 61909
cylinder heads are equipped with rocker studs and hardened washers for use with “self-aligning” rocker arms. Always check rocker-to-
valve tip alignment and adjust as needed. If using Non-self aligning rocker arms, Edelbrock recommends the use of PN 9660 guide plates
for use with 5/16” pushrods. If using guidplates the washer under the rocker stud must be removed and hardened pushrods MUST BE USED.
Valve Covers: Although Performer LT-1 heads will physically accept standard centerbolt valve covers, the emissions provisions are in different
locations. For this reason, valve covers specifically designed for LT-1/LT-4 applications are strongly recommended for use with OEM components.
Intake Manifold:Cleangasketsurfaces.Donotusecorkorrubberendseals.UseRTVsiliconesealerinstead.Applya¼”highbeadacross
each block end seal surface, overlapping the intake gasket at the four corners. This method will eliminate end seal slippage. Install gaskets and
intakemanifoldtofactoryspecifications.Torquetorecommended35ft-lbs.inthefactorysequence.Refertofactoryservicemanual.
Exhaust Headers: Any header or manifold designed for original equipment heads will fit Edelbrock Performer LT-1 Cylinder Heads. Exhaust
portsareCNC-profiledtomatchFel-Pro#1404exhaustgaskets,whicharerecommendedfortheseapplications.
Spark Plugs:Use14mmx3/4”reachgasketedsparkplugs.Heatrangemayvarybyapplication,butwerecommendChampionRC-12YC(or
equivalent) for most street-driven applications. Use anti-seize on the plug threads to prevent galling in the cylinder head, and torque to 10 ft./
lbs. Do not overtighten sparkplugs!
INSTALLATION: Installation is the same as for original equipment cylinder heads. Consult service manual for specific procedures, if necessary. Be
sure that the surface of the block and the surface of the head are thoroughly cleaned to remove any oily film before installation. Use alcohol or lacquer
thinneronalint-freeragtoclean.ApplyTeflonpipesealantorsuitablesealertoheadboltthreads.Apply30Woilorsuitablelubricantunderside
of bolt heads and washers. Torque to 65 ft./lbs. in three steps (40, 55, 65) following the factory tightening sequence (see Figure 1). A re-torque is
recommendedafterinitialstart-upandcool-down(allow2-3hoursforadequatecooling).
Edelbrock LLC • 2700 California St. • Torrance, CA 90503
Tech Line: 1-800-416-8628
®
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