The Timing Chain drives the Camshaft.
Also see: * Timing Cover * Crankshaft Pulley
Contents |
Overview
We have seen a couple of single link timing chains on A12, which is the original A10 single row chain. Insist on the factory specified double-chain, like Nissan did for later A10s.
NOT GOOD - early A10 single-row chain
NOTE: A rattle can be the trait of a stretched timing chain. Pinging/pinking has also often been mistaken for timing chain rattle
A-series engine has a short timing chain -- and with an automatic adjuster -- it rarely stretches or goes bad.
Compare to the loooooong chaing used in the Nissan KA24E engine:
click
KA24 often has timing chain problems
Checking For Wear
If tensioner spindle projection is more than 15mm, replace chain.
Replacement
Alignment
Check the cam gear alignment. It should be exactly like this:
If it is not, see Camshaft#Timing.
Slinger
Don't forget the oil slinger.
12302-18000 THROWER-OIL CRANKSHAFT
Part Numbers
The timing chain kit (timing set) includes: Cam, Crank, Chain, Tensioner
KIT SET * CLOYES Part # 94054S RockAuto.com $35.79 * CLEVITE/PERFECT CIRCLE Part # 92602 * ITM 05390500 RockAuto.com $32
Cam Sprocket
38 tooth Cam Gear (timing gear) * Sealed Power 223478 $3.50 * ITM 50022 $4.67 * ITM 50021 $4.67 * CLOYES Part # S47 RockAuto.com $9.41 * Beck/Arnley 0250282 $10.85
Cam Sprocket Bolt
Special bolt 13082
Chain
Same as SRL311 with U20 engine (for Jackshaft)
CHAIN RockAuto.com * CLOYES Part # S478 $9.40 * CLOYES 94054 $9.70 * BECK/ARNLEY Part # 0240226 * ITM 2354 $7
specs Links: 54 Pitch: 3/8 inch Rollers: Double Timing Marks: 2
Crank Gear Key
Same key is used for the engine crankshaft pulley. See Crank Pulley Parts.
Tensioner
* CLOYES Part # 95005 RockAuto.com $3.90 * ITM 60004 $6.37
Early non-return tensioner (A10 engine) * 13070-18010 ASS'Y-TENSIONER, non-return B10 [double-chain]
Early A12 engines (to April 1970) also used a tensioner on the Tension side of the chain. Apparently this was deemed unnecessary so was omitted starting May 1970.
13083-18001 TENSIONER-CHAIN TENSION SIDE -0470 13084-18000 SUPPORT-TENSIONER TENSION SIDE -0470 08110-62010 BOLT M6 FIXING TENSIONER -0470 full
Crank Sprocket
19 tooth Crankshaft Gear (Timing Crank Sprocket, Timing Crank Gear) RockAuto.com * CLOYES Part # S477 $8.87 * Sealed Power 223477 $6.17 * Beck/Arnley 0250258 $7.36
USA
B110 RAW LIST VALVETRAIN 13024-H8500 SPROCKET-CAMSHAFT 13024-18001 SPROCKET-CAMSHAFT 13082-18000 BOLT-CAMSHAFT SPROCKET 13030-18000 WASHER-CAMSHAFT 08915-2401A WASHER-LOCK 08915-14010 WASHER-LOCK 13028-18001 CHAIN-CAMSHAFT 13070-18001 ASSY-TENSIONER CHAIN 08120-63510 BOLT-FIXING CHAIN TENSIONER 08915-13610 WASHER-LOCK FIXING CHAIN TENSIONER PISTON, CRANKSHAFT & CONNECTING ROD 13021-H1000 SPROCKET-CRANK A12 12316-30000 KEY-WOODRUF 5X16 2 A12
Adjustable Cam Gear
Fitting an adjustable Camshaft gear lets you fine tune the timing. The cam vendor's recommendations are usually best, but retarding the cam a degree or two will generall shift the torque curve higher up in the RPM range. Advancing the cam will (usually) lower the power curve a few RPM.
Adjustable gears come in a few basic kinds:
- Multi-key. Rollmaster had one with nine adjustible keys in the crank sprocket
- Multi-hole. Using different holes
- Variable: Slotted holes allow a continuously variable range