Cylinder Head & Measurements

Cylinder Head & Measurements

Theory:

The cylinder head is what seals the cylinder's forming a combustion chamber. It sits above the cylinder's on top of the cylinder block.

It holds the camshaft which operates the rocker arms to which will move the rockers. That will push down on to the Intake valves & Exhaust valves.

It also contains the spark plugs, Exhaust & Intake ports, Exhaust & Intake valves, Rocker arms.

Cylinder head allows the Fuel & Air flow to the cylinder & allows the Exhaust to escape.
The camshaft pulley is what the timing belt/ chain depending on the engine, is connected to which then pass's down past a tensioner & connected to the crankshaft that operates the pistons.

Experiment:

• Carried out measurements of the Intake & exhaust valves using the micrometer - measuring six times at three points of the steam.At the top, In the middle & at the bottom - This is to find if Ovallity has a curd or if the tapered bit near the seat has been put out of shape.

• Valve seat & margin -  Using a vernier caliper to measure these two. If the margin is not at 1.0mm then the valve seat has worn bigger and valve will need replacing.

• The length of the valves - using the vernier caliper - Under heat these can stretch and will cause the valve not to shut properly, which will make the vehicle to smoke.

• Measuring of the head - Using a straight edge, light & feeler gauge. This is determine whether or not the head it self has warped in any possible way.

• Visual inspections were necessary too, If there are any sharp point anywhere, scratches or even chips on the valve, Then this will seriously cause major problems. Also to see if the head of the valve, where the rocker's connect with, had created a sharp/ curvy edge. Hans explained this as "Bure"

• Inspection of valve spring - Using the vernier caliper external measuring jaws, finding the free length of the spring. Free length has to be within 1.5mm of each other.

• Inspection of valve spring installed height & seat pressure - With the vernier caliper tool & measuring 3 times at 3 different point.

• Inspection of valve spring squareness - Take a square and place the spring against it & measure using the vernier caliper. A minus B will equal C - C being the over all squareness of the valve spring.

• Inspecting the camshaft for wear & general condition - To do this we need the second smallest Micro meter. By measuring in two different position's on the cam lobes - ( A & B), A - being the the bottom of the lobe to the top & B - being the side's of the cam lobe. This is to determine the lift of each cam lobe. Our camshaft needs replacing as all the cam lobes didn't have the same lift.

• Inspecting the camshafts journals - To do this we needed to use the dial tester. Setting the camshaft up on the "V" blocks and applying the dial tester to each journal of the camshaft. Once this done, then slowly turn the camshaft until the dial tester gauge starts to move. Then recording how much it the dial moves by. If it doesn't move then the camshaft journal is fine.

• End-float readings - This is to determine movement once the camshaft has been installed. There should 0.57mm max movement as per specifications, Our camshaft has movement of .06mm, which is good. To do this we use the dial tester set up on the end of the camshaft where the camshaft pulley attaches.

There will be more measurements to put up as the exercise has yet to be finished.

Reflection On experiment:

The purpose of all of the above is to retain the knowledge of pulling apart, finding faults, knowing how or if the fault is fixable within the workshop or not. Then successfully putting the engine together.

We have discovered that the valve's are reusable and none of them need to be replaced but do need some workshop time on each valve. The head of each valve needs to be shaved back either 1 - 2mm each. This is to give the rockers more of a flat surface to push done on the Valves.

There was no warp of the the head which was good this means this does not need replacing. If it was warped then this could effect everything that works on the inside of the head from moving in a smooth operation.

Inspection of Cylinder Head Components

Valve Steam Measurement:

 

• Measuring valve's require to be measured 6 times.

• At the top, the middle & the bottom, Then rotate 90 degrees & repeat.

• Measuring the length - Checking if valve has stretched.

• Using the vernier caliper inside jaws to measure the margin & valve seat. Valve on the right & Vernier caliper on left.

•  From the intake & exhaust rockers pushing down on the tops of the valves creates wear.

• If this has happened then the tops need to be shaved back.

 

• Inspection of valve spring free length

• Using the vernier caliper to measure the inlet & exhaust valve springs.

• Inspection of valve seat spring installed height & seat pressure.

•  Inspecting the camshaft for wear & general condition using the micro meter.

• Our cam lobes all had different lift

• Inspecting the camshaft journals for ovality.

• I found that the camshaft journals are all out & all have ovality.