Polish cylinder head is okay but skimmed the head if not nessary not recommended as your engine head life spam will less TitanRev You think I print money? Helmet Clan. Mar 3, 8, 3, 5, Suggestion is that you use a sport cam like what Sky said. I think its Sep 5, 2 1, TitanRev said:. Sep 6, 15, 3, Island Of Pearl team99ers. Apr 19, 7, 3, Sahara Desert. Thread starter. Apr 29, 1, 11 3, kepong. SkYwAlKeR said:. Jul 15, 40 0 1, Port and polishing, rough surface or mirror surface is better?
Aug 14, 0 1, Shah Alam. Jun 24, 54 0 1, Cheras. Jun 2, 2, 1 3, fire down below. Feb 5, 1, FVel said:. The added slack in the chain has a retarding effect on cam timing, which reduces compression and torque. It can also retard ignition timing if the distributor is cam-driven. Most OHC engines that use a chain drive have some type of automatic chain tensioning device, but pushrod engines do not. Consequently, the timing chain and gear set often need to be replaced in high-mileage pushrod engines.
In OHC engines with belt-driven cams, the main concern is belt failure. If the belt snaps, the cam stops turning and the engine quits. To minimize the risk of such damage, most vehicle manufacturers recommend replacing OHC timing belts at specific mileage intervals for preventive maintenance. On older OHC engines, 60, miles is the typical replacement interval. On newer OHC engines, it is , miles. Cam failures can occur if there are lubrication problems in the engine. Lifters create a lot of pressure and friction on the cam lobes, so the lobes and cam bearings must receive lots of oil.
If oil pressure is low or the oil is dirty, the cam may suffer accelerated lobe wear and ultimately lobe failure resulting in a dead cylinder no valve action. This type of cam damage can also be caused by using the wrong viscosity motor oil. In overhead cam engines, it is a long way from the oil pump to the top of the cylinder head. On cold mornings when the oil is thick, it can take quite a few seconds for adequate oil pressure to reach the cam.
That is why most vehicle manufacturers recommend using 5W oil rather than 10W or 10W for cold weather driving. Cam breakage or seizure is another problem that can occur in OHC engines. The cause may be inadequate lubrication but in many instances it is caused by head warpage. When an OHC engine gets too hot, the cylinder head tends to swell and bulge up in the middle.
This changes the alignment of the cam bores in the head which may cause the cam to bend, bind, seize or break. Camshafts are often replaced to increased engine power and performance. But choosing an aftermarket performance cam is not as simple as it sounds. A lot of things must be taken into account to find the "right" replacement cam. These include not only the engine and vehicle application, but also the engine's compression ratio, type of fuel delivery system, other modifications intake and exhaust manifolds, exhaust system, etc.
But most important of all, what exactly do you want from an aftermarket performance replacement cam? More power? More torque for towing? Better mileage? As you look through the various performance camshaft manufacturer catalogs, you will notice two things. The first is that there are many, many different cam grinds from which to choose. The more popular the engine application small block Chevy, for example , the greater the selection of cams that are offered.
The other thing is that there are specific recommendations for each type of cam. So the best advice here is to follow the camshaft supplier's advice. A typical stock replacement cam either a new cam or a reground, is essentially a duplicate of the OEM grind.
This type of cam is used to restore the original performance of the engine, and is a safe choice for a stock rebuild. The next step up are the cams with slightly "enhanced" profiles. Idle quality, driveability and emissions remain about the same as stock but the engine puts out more power and gets somewhat better fuel economy. Once you get beyond stock replacement cams, the selection process gets more complicated because each grind is designed for a specific type of application. Vehicle weight, drive gear ratios and type of transmission automatic versus manual take on greater significance as do the modifications to the engine itself compression, displacement, carburetion, valve size, valve train, etc.
The most common mistake to avoid when choosing a cam is to "over-cam" an engine. Installing a hot cam in an otherwise stock engine can create a bad mismatch between components, and that hurts rather than helps performance. A long duration cam with a lumpy idle may sound really hot, but may not provide as much low end punch as a stock cam.
Emissions can also be a problem with long duration cams. When comparing cams, you will find a number of specs listed. These include lift, duration, overlap, lobe separation and timing. Valve lift is how far the cam opens the valves.
Increasing valve lift increases the distance the valve opens, which makes it easier for more air and fuel to enter the cylinders. Gains in airflow will be achieved by increasing lift up to the point where either the area of the valve opening or port becomes the limiting factor on airflow, or mechanical interference is encountered between the valve and piston, valve springs or spring retainer and valve guide.
One way to specify valve lift is to measure "lobe lift. Please contact our Technical Department for further information. How an abnormal wear pattern looks on a rocker arm wear pad. How an extremely worn rocker arm wear pad looks. Adjustable Cam Gear: Adjustable cam gears are generally used to correct camshaft timing after the head has been milled or when the block has been decked.
Valve Train Valves, Seals, Springs, etc : Choosing the correct camshaft and matching valve train components is crucial for maximum performance as well as reliability. In order to have a good working top end, all of your components should be matched to each other.
For example, your valve springs should match the lift of the cam so the valves can open and close how they are intended to with proper retainers. Valve-Piston Clearance: One of the most important details that is often overlooked is piston to valve clearance.
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