Refinement and modernization of the cylinder head (cylinder head) is one of the ways to increase the power and efficiency of the engine. At first glance, the head looks simple, but in reality, race engine engineers pay a lot of attention to it. For self-preparation of the head for increased power, a significant amount of manual work will be required.
Necessary
high-speed manual polishing and processing machine with several grinding heads and scrapers
Instructions
Step 1
To rework the inlet, fit valves of the same width, equal angles and perfectly round. Also, chamfer 30 degrees and remove any sharp edges on the underside of the intake valve. Work the inlet around the valve guide so that any obstructions to the flow of the air / fuel mixture are reduced in height and width. Only remove metal from areas that significantly restrict flow. Excessive sanding can reduce power.
Step 2
In the area of the intake valve seat, locate the characteristic ridge just below that seat. Treat this area carefully. Again, only remove metal from areas that severely restrict airflow. The transition from the valve seat area in the direction of flow should be smooth, without protrusions, with a smooth radius. Cut the opening of the inlet so that it is not a traditional rectangular shape, but a trapezoidal one. Do not remove metal from the bottom of the duct when doing this. Also, coarsely sand the inlet surface with 80-100 grit bar or sandpaper.
Step 3
To further enhance engine performance, purchase and install racing cylinder heads and high-lift camshafts. When choosing a camshaft, keep in mind that for a simple forcing of the engine, a valve lift of 12, 7 mm with bronze guides for their bushings is enough. When lifting valves up to 14 mm, be sure to use roller rockers (rockets), which will increase the life of the valve stem and guide bushings. Racing engines can have valve lift of up to 15 mm, but the life of these parts will be noticeably less. Engines for ring and off-road competitions use camshafts with a valve lift of up to 16.5 mm, and on dragsters up to 17.8-21.6 mm, but the resource of the valve drive mechanism is also limited to hours or minutes.
Step 4
When installing a sports camshaft, replace the valve springs with specially designed springs for the specific camshaft. When using bronze guide bushings, select one with Teflon seals. They will keep oil from entering the high pressure passages in the exhaust system of high-powered engines.
Step 5
Remove the cylinder head and apply a layer of plasticine to the piston head. Install a cylinder head with an unusable gasket, tighten the mount, install and adjust the rocker arms and rods. Turn the crankshaft at least 2 full turns. Remove the cylinder head and measure the thickness of the plasticine layer at its thinnest point. It should be at least 2 mm in the area of the inlet valve and at least 2.5 mm in the area of the exhaust valve. Check each cylinder in this way to make sure that the scatter in the parameters of the parts does not lead to contact between the piston and the valve.
Step 6
To upgrade the combustion chambers, polish the surface. This will reduce the absorption of heat that can be channeled to create additional power and reduce carbon build-up. After the valves have been machined, measure the volumes of all combustion chambers in order to align the chambers in all cylinders when machining them. Avoid over-enlarging the combustion chamber. Do not change the shape of the combustion chambers until you have studied the effect of the modifications made to the cylinder head on the propagation of flame in the engine cylinders. Treat the combustion chambers only after the valves have been repaired. When carrying out work, take measures to protect the valves and seats from accidental damage (valve simulators).
