In class we messured most of the engin parts to check for wear or damage. we checked these messurements with the manifactures specs to see if the part was reusable or had to be replaced.
CAMS
i messured the lobes of the cam and barto see if it was bent or worn. i checked this with a dti gauge
also on the cam we checked the oil clearnce with plasit gauge
journals were visualy inspected for scartches clogs in oil groves so that oil can flow through easy for lubrication.
VALVES
we messure the tickness and lip size of the vlaves to see if it has to much play in the vlave seals and if the valve sits on its seat properly. i messerd this with a micromiter
VLAVE SPRINGS
i messured the compression of the valve springs with a valve spring tester. i also checked the springs against a square to see if they were slightly bent and needed to be replaced. a few springs needed to be replaced as they were not square at all.
PISTON
i messured the oil clearences between the piston rings to see if they were worn and need replacing.also messured the diamiter of the piston to see if it had enogh clearince in the boar.
i made sure the con rod was straight and not bent, worn or damaged. having a bent or danaged con rod can cause alot of internal problems and make the piston wear against the boar and possibly bend the crank.
CRANK SHAFT
i messured the the journals on the crank to check for ovality and taper to see if there was enogh oil flow and lubrication to the engin parts. i also checked the oil clearnce with plasti gage to check oil clearnce through the crank
Thursday, September 22, 2011
Sunday, September 18, 2011
4 stroke block
the block houses the pistons con rods and crank. the block is wear the combustion happens there for the block is very strong and usauly made of cast steel. inside the block are boars wich house the piston
PISTONS
the piston slides up and down the boar buy the rotation of the crank. the rotation of the crank starts of either by a starter moter or a bump start. the piston draws air and fuel into the boar, compresses it, the park plug ignites the air and fuel pushing the piston down creating a rotating motion in the crank to help pump the other pistons up and down. with out the piston it would be impossable to create compression or power. on a 2 stroke some pistons are curved to circulate the air and fuel around the boar instaed of straight out the exhaust. on a 4 stroke standerd pistons have flat tops or small indents so the piston dosnt hit the valve. on performance engins when high revs or a higher octane fuel is used a forged piston can be uesd for exxtra strength so no holes or damge can be don to the piston head. the piston has sevral groves on the side for oil rings. these oil rings help lubricate the boar and piston as it pumps up and down and also stops oil from getting on top of the piston to wear combustion takes place. worn or broken rings creat alot of smoke as oil is being burned with the air and fuel.
GUGEN PIN
the gugen pin holds the piston to the con rod. it act like a bearing with help of the oil for lubrication so that the piston can stay straight in the boar and the con rod can rotate with the crank. it is important that the gugen pin is strong as a weak gugen pin can cause alot of damage if it brakes.on a 2 stroke the gugen pin runs on roller bearings as the lubrication is air, fuel and oil. on a 4 stroke it ues oil to lubricate and rotate. with out oil the parts can heat up and melt togeather or sease reacking the engin.
CON ROD
the con rod or connecting rod coneect the gudgen pin and piston to the crank. the con road connects to the crank by main journals. instead or caged roller bearings in these journals like on a 2 stroke there are oil groves and sleeves wich relei on the oil to lubricate these moving parts. when inspecing the con rods its best to check that they are straight non damged like buring or chipping and havnt been case hardend as this can effect the overall strength.
CRANK
the crank is a vital part of the engin as it truns up and down movement into rotaing movement wich is transferd onto the fly wheel. the crank is held to the bottme of the block by main journals. these main journals have the same lubricating system as the journals that hold the con rod to the crank. the crank holds the kenitic energy of the piston and helps pump the other pistons around. when inspecting the crank i checked the size of journals. if it was bent with a dti gaguge. the crank was fine with the manifaciures spces.
PISTONS
GUGEN PIN
the gugen pin holds the piston to the con rod. it act like a bearing with help of the oil for lubrication so that the piston can stay straight in the boar and the con rod can rotate with the crank. it is important that the gugen pin is strong as a weak gugen pin can cause alot of damage if it brakes.on a 2 stroke the gugen pin runs on roller bearings as the lubrication is air, fuel and oil. on a 4 stroke it ues oil to lubricate and rotate. with out oil the parts can heat up and melt togeather or sease reacking the engin.
CON ROD
the con rod or connecting rod coneect the gudgen pin and piston to the crank. the con road connects to the crank by main journals. instead or caged roller bearings in these journals like on a 2 stroke there are oil groves and sleeves wich relei on the oil to lubricate these moving parts. when inspecing the con rods its best to check that they are straight non damged like buring or chipping and havnt been case hardend as this can effect the overall strength.CRANK
the crank is a vital part of the engin as it truns up and down movement into rotaing movement wich is transferd onto the fly wheel. the crank is held to the bottme of the block by main journals. these main journals have the same lubricating system as the journals that hold the con rod to the crank. the crank holds the kenitic energy of the piston and helps pump the other pistons around. when inspecting the crank i checked the size of journals. if it was bent with a dti gaguge. the crank was fine with the manifaciures spces.
Wednesday, September 14, 2011
4 stroke engins
HEAD
the head of the engin holds alot of important componets needed for the combustion process. the head has intake and exhaust ports wich are uesd to feed fuel and air into the boar for compression and exhaust ports wich connect to the exhaust manifold to remove waste fumes after combustion. inorder to let air/fuel and exaust in and out of the engin valves are needed to open and close to seperate and deliver presices amount of mixture for combustion. the valves open and close by being pushed open by a push road system wich has rockers or a rotaing camshaft with cam lobes shaped like a triangle with rounded corners.the cams are driven off the crank shaft by a belt or chain. ensureing the timing of the valves is esensual as valves out of time can cause majoir damage to engin parts.
HEAD CONPONETS
cams: cams are a very important part to a head and the engin. the purpose of the cam is to push down on the cam bucets to compress the valve spring and open the valve or to push a push rod up into a rocker so the rocker pushes down on the valve to open it. the lobes on the cam are used to open the valves. the lobes are rounded and triangle shape so the valves open and close smothly and not cause as much wear to the valves or cam buckets. the cams are atached to a cog on either on the out side of the engin or the inside depending on weither its driven by a belt or cahin. the belt or chain then conects to the pulley on the crank so that the valves open at the corret time of the piston stroke. on the cam we messure the cam lobes ,wear and bend in the cam. the cams were between the manifactures specs and were still uesable if the engin was to run again.
VALVE SPRINGS
the purpose of a valve spring is to return the valve after its being compressed either by the cam or rocker. with out a valve spring the valves would stay open and the engin would not run, also the valves could bend causeing damage to the valve seal, piston and sevral other engin conponets. valve springs can come in diffrent materails for special conditions such as titanium for high performance. in our practical we checked to see if the springs were squar incase they mite be slightly bent witch could indercated further problems. the most the springs were out were .2 mm. we then messured the length of the springs with a vernier to check the length against manifactures specs . all the valve lengths were between the manifactures specs. we check the length and squarness to ensure that the springs are still doing there job and do not have exstesive wear. short valve springs may cause less resitance when valve returning or mean extensive wear has taking place. we checked the spring tensioner to ensure they were compreesing to the right length acording to manifactures spec. doing this can idicated if the valve springs are worn and need replacing to resolve a problem.
VALVES
valves are used to let in air and fuel for combustion and to let out exhaust fumes. some head shave sevral valves per cylinder for more flow there for more power. valves sit in a valve seat wich hold the valve in but still let it have a smoth flow for when the cam or rocker pushes the valve open. the valves have valve springs locaters seals to seal the spring and on cam shaft heads have a cam bucket . this set up helps the valve to open and close when needed. in our practical we messure the valve seats , thickness of valves and inspected the valve for damage or corrosion. all the valves ahd small wear but were still in usable condition and fitted well in the valve seats.
OVERALL HEAD INSPECTION
overall the head was in a fiarly good condition. most of the componets were within the manifactures specs and only had small wear. although there were a few cam lobes and springs that were a little over the manifacture specs. the condition of the haed was avrage. it had small warpage. scratches and a tiny bit of chiping on the outside. when assemberling the head i had to time the cams together and check valve clearences with a fealer gage to manifactur specs. to do the valve clearinces i would have to replace the pads on the valve bucket. the bolts and threads on the head were fine and only a few bolts were missing before pulling apart. bolts were torquid down to half the manifacutres specs as the engin has being pulled about hundreds of times.
the head of the engin holds alot of important componets needed for the combustion process. the head has intake and exhaust ports wich are uesd to feed fuel and air into the boar for compression and exhaust ports wich connect to the exhaust manifold to remove waste fumes after combustion. inorder to let air/fuel and exaust in and out of the engin valves are needed to open and close to seperate and deliver presices amount of mixture for combustion. the valves open and close by being pushed open by a push road system wich has rockers or a rotaing camshaft with cam lobes shaped like a triangle with rounded corners.the cams are driven off the crank shaft by a belt or chain. ensureing the timing of the valves is esensual as valves out of time can cause majoir damage to engin parts.
HEAD CONPONETS
VALVE SPRINGS
the purpose of a valve spring is to return the valve after its being compressed either by the cam or rocker. with out a valve spring the valves would stay open and the engin would not run, also the valves could bend causeing damage to the valve seal, piston and sevral other engin conponets. valve springs can come in diffrent materails for special conditions such as titanium for high performance. in our practical we checked to see if the springs were squar incase they mite be slightly bent witch could indercated further problems. the most the springs were out were .2 mm. we then messured the length of the springs with a vernier to check the length against manifactures specs . all the valve lengths were between the manifactures specs. we check the length and squarness to ensure that the springs are still doing there job and do not have exstesive wear. short valve springs may cause less resitance when valve returning or mean extensive wear has taking place. we checked the spring tensioner to ensure they were compreesing to the right length acording to manifactures spec. doing this can idicated if the valve springs are worn and need replacing to resolve a problem.VALVES
valves are used to let in air and fuel for combustion and to let out exhaust fumes. some head shave sevral valves per cylinder for more flow there for more power. valves sit in a valve seat wich hold the valve in but still let it have a smoth flow for when the cam or rocker pushes the valve open. the valves have valve springs locaters seals to seal the spring and on cam shaft heads have a cam bucket . this set up helps the valve to open and close when needed. in our practical we messure the valve seats , thickness of valves and inspected the valve for damage or corrosion. all the valves ahd small wear but were still in usable condition and fitted well in the valve seats. OVERALL HEAD INSPECTION
overall the head was in a fiarly good condition. most of the componets were within the manifactures specs and only had small wear. although there were a few cam lobes and springs that were a little over the manifacture specs. the condition of the haed was avrage. it had small warpage. scratches and a tiny bit of chiping on the outside. when assemberling the head i had to time the cams together and check valve clearences with a fealer gage to manifactur specs. to do the valve clearinces i would have to replace the pads on the valve bucket. the bolts and threads on the head were fine and only a few bolts were missing before pulling apart. bolts were torquid down to half the manifacutres specs as the engin has being pulled about hundreds of times.
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