Installation Instructions
LS1 Small Block Chevy Aluminum Cylinder Heads
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ATTN: Please read through all instructions before attempting cylinder head installation.
Springs:
It is the customer responsibility to check and make sure that spring pressures are correct for his cam.
Valve Guide Clearance:
Intake and exhaust guide clearance are .00125, on some severe applications with nitrous,
marine, or blower usage looser guides might be required.
Important:
Apply anti-seize to all bolts and spark plug threads to ensure a long thread life.
*WARNING*
Piston dome to cylinder head clearance must be checked prior final assemble of engine.
Piston to valve also needs to be checked, pay special attention to the outside edge of the
valve to the inside edge of the valve relief in the piston.
Compression ratio and piston to valve clearances must be checked before assembly. Part numbers
1610 through 1680-1 with the 2.080 intake valve usually will not fit a piston without valve
notches having proper relief’s.
Coolant:
It is important to maintain a 50/50 mix of antifreeze in the cooling system to prevent corrosion
of aluminum heads. Do not use tap water use distilled water, most supermarkets have purified or
distilled water. Check labeling to verify purified through deionization.
Torquing:
We suggest NOT using a torque wrench on intake and exhaust manifold bolts. Just snug up
hand tight with a wrench only.
Valve Seats:
Both intake and exhaust valve seats are heat-treated and compatible with unleaded fuels.
Accessories:
Although AFR LS1 heads will accept OEM components; we highly recommend that premium
aftermarket hardware be used with your new heads.
Head Gaskets:
Use GM#12498543 or 12498544, Fel-Pro#1041 or AFR #6830 .040 thick.
Intake Gasket:
Use factory o-ring style gasket or AFR #6830.
Exhaust Gasket:
Use GM stock replacement gasket.
Valve Cover Gasket:
Use factory style o-ring gasket.
Head Bolts and Studs:
High quality head studs or head bolts with harden washers must be used to
prevent galling of the aluminum head. Recommended head bolts are ARP#134-3609,
for head studs use ARP# 234-4316. For maximum head gasket clamping AFR recommends
head stud kits. VERY IMPORTANT: You cannot re-use the factory LS1 head bolts.
They are “torque to yield” design and can only be used once.
Head Bolt Torque:
Apply moly-oil mixture to washers, and area around head bolt to prevent
galling and improper torque readings. 11MM ARP torque to 70 ft. lbs. with moly
lube, 8mm torque to 23 ft. lbs. with moly lube. A re-torque is recommended after
initial start-up and cool down (allow 2-3 hours for cooling). Sealer should be
applied to all head bolts or studs that enter into the blocks water-jacketing system.
Permatex is a good general-purpose sealer.
Spark Plugs:
Use AC 41-974 Platinum as a starting heat range. Plug selection is of course dictated
by many factors including RPM levels, compression ratio, and fuel type. Forced induction
or nitrous applications usually require 1 to 2 heat ranges colder. The ignition manufacturer
should determine spark plug gap. You can cross reference to your favorite brand if desired.
For nitrous or super charged applications a good starting point would be Auto Lite 3942, which
is 2 ranges colder than stock.
Cleaning:
AFR thoroughly cleaned your heads prior to shipment. Your heads were washed in water soluble
chemical agitation tank and blown out with high pressure air 3 to 4 times before they were boxed.
However during some machining operations chips are packed and wedged into the water jacketing
and occasionally come loose in transit. Keep in mind one chip the size of a dime breaks into
hundreds of tiny chips and makes the situation appear much worse than it is in reality. It is not
usually if you blow high pressure air into the water jacketing to see additional foreign debris, or
chips finding their way out. AFR recommends that you thoroughly blow out your heads prior to installation.
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