How to build a small block on a 318?
Since the turn of the decade, Chrysler has not built a rear wheel drive V8-powered car.During the late 1980s, the cars that had V8s under their hoods were just as appealing to performance enthusiasts as the front-wheel driven vehicles that replaced them.
There is a strong demand for high performance Chrysler small block engines.The Ram and Dakota models have been offered with Chrysler's "LA" small block for several years, and that demand is fueled by truck owners.
The 273 cid model of the LA family of small blocks was introduced in 1964.The small block had a 318 cid model in 1967.Over the years, this particular engine has generated a lot of confusion.
The original 318 engine, which was produced between 1957 and 1966, was a larger displacement version of the 277 and 301 engines.The old A engines and the newer LA powerplants have very few parts in common.Nobody cares about performance parts for the old A series engines.
The LA engine didn't have much of a performance orientation until 1968.Initially, it was simply a torque generator for Chrysler's larger vehicles, but in 1971 a 360 cid version was introduced.
displacement is noted on most castings so it's easy to distinguish Chrysler blocks from one another.The blocks are virtually the same in appearance, but they have different left-side motor mounts.Although kits are available to convert the blocks to a four-bolt main configuration, they should not be used.There isn't enough material in the web areas to comfortably handle the added bolts.
Additional block strength is required if four-bolt mains are required.The only way to get both is with a race block.Adding four-bolt mains to an old Trans/Am block is also possible.
The production blocks were cast using a thinwall process and should be considered a maximum.If you plan to machine the cylinders of an LA engine more than.030′′ over size, it is advisable to sonic check them.The maximum safe over bore is.020′′.
Standard high performance block preparation is the same for a small block Chrysler as it is for any other engine.It usually includes removal of casting flash from the lifter valley area, enlarging of the oil return holes in the valley, cleaning all critical threaded holes with a tap, and honing the deck surfaces to assure they are square and flat.
High performance small blocks should be made to yield a zero deck clearance between the flat portion and the block when the former is at TDC.A zero deck makes the engine less likely to explode.The only way to achieve a zero deck is to have the pistons stick out of the block at TDC.
Regardless of the desired deck clearance, take the time required to assure proper milling.Small block Chrysler engines have only two rows of head bolts so the block and head mating surfaces must be absolutely flat if the head gasket is to enjoy a long and successful life.Thread integrity and head bolt quality are important for high performance bolts.
Any high performance engine will benefit from honing the cylinders with Torque plates in position.If optimal ring seal is to be achieved, the use of Torque plates during honing is absolutely essential, as cylinder walls can move as much as.004′′ when the head bolts are tightened.After boring to assure optimum cylinder wall finish, Grimes hones at least.004′′ to,000.005′′.When making a block for high performance usage, Align honing is a standard procedure.
Prior to 1973, all LA engines were equipped with forged steel crankshafts.crankshafts are interchangeable between the engines that have the same stroke and main journal diameter.Since they have 2.81′′ diameter journals, not the 2.50′′ found in smaller displacement LA blocks, retrofitting isn't an option.
The balance factor will vary greatly depending on the connecting rods and pistons used in the original configuration.The addition or removal of an excessive amount of material may be required when using a crank in an engine with a bore size different from the one to which the crank was originally mated.The most efficient approach is to use a crankshaft that was originally installed in an engine of the same displacement as the one being rebuilt.
When preparing a crankshaft for use in a high performance engine, it's best to buy a little insurance by taking the extra time required to radius the oil holes, polish the journals and add a generous fillet radius.It will be necessary to make sure the bearings are compatible with the new radii.
There are four crankshaft numbers of interest, two of which are cast iron.Although a forged crankshaft is stronger than a cast iron one, it's usually not a problem in a high performance street engine.When selecting components, be aware that cast iron 340 crankshafts and LA forged cranks are internally balanced.
It is against the law to install the vibration damper and flywheel on a forged crank.The dampers installed on the crankshafts are not suitable for other parts of the assembly.
The 1972 and later damper have a symmetrical pulley bolt pattern, while the 1971 and earlier damper had a non-symmetrical pattern.The 340 cast crank requires a Chrysler damper.There is an option to install a damper.The fluidampr p/n 71420 is compatible with all internally balanced engines.
Both the rod and main bearings should be used.Top quality parts can be installed.Most high performance Mopar specialists recommend main bearings with a grooved upper half and full width lower half.When fitting the upper halves, make sure the oil hole is the same size as the bearing saddle's oil supply hole.
Deburr the hole if it is necessary to drill a larger hole.When the pedal is beneath the foot of an uneducated driver, tight clearances can prove detrimental to the life of the bearings; engine oil must be used.
High pressure and high volume oil pumps are standard issues for high performance engines.The need for wide bearing clearances has been eliminated thanks to metallurgy and lubricating technology.The need to flood an engine with oil is eliminated by tighter clearances.
A standard oil pump will provide more pressure and volume if a small block Chrysler is assembled properly.If the crankcase capacity isn't adequate, high volume pumps can be a liability because they can suck the oil pan dry and cause oil starvation in the upper part of the engine.
The old guideline of 10 psi for every 1,000rpm is applicable to Chrysler small blocks.The Chrysler oil pump blueprints call for tip clearance between the inner and outer rotors to be less than.01.There is a clearance between the pump face and the rotors.The required amount of pressure in engines that won't operate above 6,000rpm for extended periods should be provided by standard pumps.
A high pressure oil relief spring can be used if oil pressure isn't adequate.An additional volume can be obtained by installing a long rotor kit.
It is possible to install a windage tray.273, 318, and 340 engines are offered by Chrysler.A hardware installation kit is required in both cases.
The oil pan selection for a Chrysler small block engine is dependent on where the engine will be installed.Vans, passenger cars, and trucks all need a pan with a rear sump.
The Chrysler small block connecting rods are the same.There is a good bit of integrity in the connecting rods from Mopar.The 340 rods are bigger and stronger than the other ones.The part numbers have wrist pins.The four-barrel rod has a pressed pin and is a heavy duty forging.The pressed pin design of the small block rods resulted in a 6.123′′ center-to-center length.
One area in which attention to detail is important is this.The compression distance of replacement small block Chrysler pistons can be different.Some pistons will give a deck clearance of.082′′ while others will stick out above the block's deck surface.The desired amount of deck clearance will be provided if the selected pistons are compatible with the cylinder heads.
The standard bore diameter for a 340 engine is 4.040′′, while a 360 has bores that measure 4.000′′.It would be wrong to say that a 340 would fit the bores, because it has a 3.31′′ stroke.
As soon as possible, verify the compression distance.To provide the desired compression ratio, it will be necessary to determine the volume of the combustion chamber.The flat top pistons have either two valve reliefs, a trough, or a dish.
The compression ratio will be below 9:0 with the large combustion chambers found in many late model heads.The compression ratio for most street performance engines should be between 9.0:1 and 9.5:1.According to the manufacturer's recommendations, the Pistons should be fit.Some forged pistons are designed for a clearance of.0015′′ or less.
There is a Speed-Pro® ring with a moly top, cast iron second, and low tension oil ring.Follow the recommendation of the ring manufacturer when it comes to cylinder wall finish.Race engine builders used to have a love affair with exotic stones, mirror finishes and other tricks.
The ring width is determined by the pistons and is usually preferred for street engines.There is a trade-off.Wider rings don't seal as well at highrpms because they are heavier.
The ring end gap is more important in high performance engines than it is in grunt-and-groan ones.The file-to-fit rings are larger in diameter than the bore so that the end gap can be precisely set.When hypereutectic pistons are used, the minimum end gap is usually much larger.
The hypereutectic material transfers heat more slowly than a standard cast or forged Piston.The advantage is that the heat can be converted to power.The end gaps for the top ring need to be.026′′ to.The information can be found in the instructions for the installation of the piston.
Don't wind the rings onto the pistons if you use a proper ring expander.Make sure that the vertical clearance between the rings is tight.The grooves for 1/66′′ rings should be.065′′ tall.Both instances have tolerances of.0005′′.
Every gearhead loves the sound of an engine that has a long duration camshaft.The sound of an engine producing power isn't guaranteed.The safest bet for an engine rebuilder is to be conservative with the duration of the camshaft.
The detonation is caused by high compression and short cam duration.Power output is zapped by low compression and long cam duration.To assure compatibility with pump gas, the goal is to select complimentary components that result in an engine that pops the gauge to 165-175 psi in a cranking compression test.Competition engines that are fueled by high octane racing gas should register about 220 pounds per square inch.
A high performance grind increases the power of the engine by raising the valves and holding them open longer.The latest computer-aided designs offer significant power increases without having to rely on excessively long duration which results in a rough idling.
The cam lobes have been designed in the past few years to open and close valves at higher speeds so that they reach full lift sooner.Increased air flow potential leads to more power, all other things being the same.Current camshaft designs deliver increased power while still maintaining good drivability.
What about mechanical lifters?Unless you are building a race engine, avoid them.Extra maintenance and increased potential engine speed are required.The safety valve on the lifters will serve you well, especially with customers having more money than sense.
It is relatively easy to pick a cylinder head for a Chrysler small block.The best choice for high performance engines is a large port casting with intake and exhaust valves.The heads were originally installed on the 340 engines.
Intake valve diameter was lowered in 1972, but port size remained the same.The large port heads with the smaller intake valve are suitable for 318 engines, while the small port castings with 1.75′′ intake and 1.50′′ exhaust valves are good for 273 engines.
The W2 head is the obvious choice for serious street performance and racing applications.The chance of finding a pair through normal rebuilder channels is slim because these heads were never installed on a production engine.At Chrysler-oriented swap meets, they can be found from Mopar Performance.
Regardless of the castings used, preparation should include a multi-angle valve job with cuts below the valve and a 30 top cut.You should not sink the valves.If the seats are worn excessively, install new ones, which are often necessary with older castings not originally designed for use with unleaded fuels.
The larger the diameter, the greater the air flow potential and the higher the valves are in the chamber.The distance from the valve seat to the short turn radius is a general rule.Installation of oversized valves makes it easier.
Clean up the valve bowl area to make the most of the port's flow potential.The goal is to blend the areas where the two surfaces meet and minimize any flow restrictions.Most customers will expect the port openings to be matched to the gasket size, which is not required for street performance engines.The effect on performance is small.The effect on a buyer's perception of power potential is significant.
Installation of valve springs is a part of any cylinder head reconditioning.If the spring offers a minimum of 100 lbs, most of the milder performance cams don't need anything more than a decent quality valve spring.The installed height of the seat is 1.700′′.Spring seatmachining is required for more radical camshafts because of their larger OD (1.430′′ versus 1.250′′).Premium quality valves should be fitted to the heads.