The LA 318 is a V8 engine from Chrysler and is a true workhorse of an engine. This model uses a single two-barrel carburetor for most of its life; takes regular gas, delving reliable power with relatively good economy. It also comes with hydraulic lifters, so it was longer lasting for most drivers. The basic specs of the 318 that started life in 1968 were torque, lbs.-ft. 340 @ 2400 with a compression ratio of 9.2 to 1, it came with 3.91” bore and a 3.312” stroke. In 1971 these specs changed to become 155 hp with 235 @ 4,400 torque, with an 8.6 to 1 compression ratio.
Next comes the 340 six pack that came just before the 1971 upgrade, and this gave you 250 horsepower @4,800 rpm, and torque was listed as 345 @ 3,400 rpm. The next change came in 1973; this was when Chrysler replaced the valve seats with hardened valve seats that would handle unleaded gas. The new valve seats could heat up to 1700°F and would be air-cooled.
In 1976, the Slant Six Valiant 318 V8 model came out, and this engine sported a low-speed pass of 475 feet in 11 seconds. The next addition came in 1978 when Chrysler integrated an adaptor to receive a magnetic probe for magnetically timing the ignition. These engines had cast iron cranks and hydraulic valve lighter, and the carb was half a pound lighter than the previous model.
The next big change came in 1980 when Chrysler lightened the 318’s design by restructuring the block, cam, exhaust manifold, and rear main bearing cap.
In 1985, Chrysler followed up with yet another upgrade, and this came by switching the original hydraulic lifters to a hydraulic roller lifter and adding a new matching camshaft. This change made life easier especially with cold starts and increased the overall engine life. The new 318 compressions was raised from 8.7:1 to 9.0:1, and the power of the 318 rose to 140 hp and 265 lb-ft.
The end of the 318 came in 1989, but just before that happened, Chrysler added EFI, and this increased the power by 20% giving the last year of the 318 170 hp and 280 lb-ft of torque.
Now let’s take a look at a few 318 Stroker kits:
SCAT 1-98005BI SB CHRYSLER 318/390 STREET AND STRIP BALANCED ROTATING ASSEMBLY – 10.9:1 ICON FLAT TOP PISTONS
Scat Street Strip rotating assembly kits deliver performance that builds up to 600 horsepower.
This is a Chrysler SB Scat with internal Balanced Assembly. It comes with a Scat Series 9000 Cast Steel Crankshaft with a 4” stroke. The Icon flat top pistons are forged, and the rod length is 6.123”. This kit comes with 2 pieces rear main seal and a Scat Series 9000 Cast Steel Crankshaft. You also get a Scat 4340 Pro Comp I-beam Connecting Rods with ARP 7/16″ Cap Screw bolts. This kit is built for a 9.578” high deck block, and the compression ratios are 62cc 11.7:1, 68cc 10.9:1, and 70cc 10.7:1
Mancini Racing Stroker Kit, 318-390 Cubic Inch, 0.984 Pin
The Mancini 318 Stroker kit comes with Mopar Performance cast steel crankshafts that have radiused fillets and a 6-bolt pattern on the crank flange with a crank stroke of 4”. The rods are Eagle ESP H-beam connecting rods. These are 2-piece, forged, 4340-certified steel that was vacuum-degassed, and come with a 190,000 psi rated 7/16 ARP 8740 (750 Horsepower rating) and 230,000 psi rated, 7/16 ARP 2000 rod bolts (1200 horsepower rating).
The pistons are Strip Diamond Pistons designed to fit most OEM open and closed chamber heads and integrate perfectly with aftermarket Edelbrock, and Indy heads. The rods ratios are configured for .018″ -.025″ deck height @ 9.600″.
The bearings on this kit are split between the H series and the P series, where the H series have hardened steel back and thin overlay. The P series are used for high rev engines, and are the oldest in the Clevite 77 brand, and built with steel backings with extra-thin overlays to prevent overlay fatigue