18
Jan
In the case of diesel engines there is no spark plug and the process of compression itself causes the diesel oil to ignite. Depending on how long you ran this engine for will determin to the extent of how much you should pull this engine down to check for signs of component failure.
In short higher compression makes an engine more efficient.
Too much compression in engine. Too much compression can make your tracks distort. This distortion can sound cool on a rock mix but most of the time you wont want your mix to sound super compressed. To avoid over-compression but still keep your levels in check automate the volume of your tracks.
Automate the volume of your vocals and instruments. The usual problem is something partially filling the cylinder before the compression stroke. So if you drive through flood water and it gets into the cylinder or overfill with oil which forces past the piston rings you will get a higher compression pressure.
Too much pressure and the connecting rod bends or something breaks. Most likely its a engine with the known Automatic Compression release failure. You should see the intake valve bump open on the compression stroke if you remove the valve cover and rotate the engine by hand also post the engine Model and Type numbers they are stamped into the valve cover.
But just for the sake of an answer a exhaust valve could be stuck and raising the compression or like one mentioned carbom build-up. A worn cam would also give you a higher reading. But if neither cylinder is at spec remember you gave us no numbers it could be worn rings and compression is leaking.
Bottom line is we need more info. A highly compressed engine will not be able to work smoothly because of the too much pressure on engine and you will find it hard to start the engine. Likewise low compression in the engine will be slow and retarding and it is a warning sign of leakage in your engine.
I teach small engines at a high school and had the too much compression issue in some of our 55hp OHV briggs engines that the students tear down measure and reassemble. Ive attached a couple photos from the textbook I remembered I had once the local small engine guy tipped me off about the compression release. Hook the battery to each appropriate lead and then make and break the negative connection to force a discharge spark from the end of the plug wire as you hold the wire near the engine case 14 inch air gap.
270 pounds of cranking compression is quite excessive and will seriously do damage to the wrist pins rods and main bearings. Depending on how long you ran this engine for will determin to the extent of how much you should pull this engine down to check for signs of component failure. Check the compression release by turning the flywheel the direction of rotation with the spark plug out Watch the intake valve open and close.
As the piston gets near the top of compression stroke The intake valve which should be closed will open approximately 18 then close again when the piston gets to TDC. Its hard for the compression to be too high if it is it can be due to carbon buildup in the cylinders. The result is engine knocking.
If its too low you have some leakage past the rings or valves and that reduces power out and efficiency. But if the compression ratio is excessive an engine is vulnerable to detonation the uncontrolled spontaneous combustion of the airfuel mixture in the cylinders. Detonation is extremely harmful to an engine.
I compare it to hitting your funny bone with a hammer it sends a shock wave through the entire system. Why is compression desirable. In short higher compression makes an engine more efficient.
Raising the compression ratio increases cylinder pressure and cylinder pressure is what drives the pistons turns the crankshaft and ultimately makes the wheels go around. The effect of higher compression ratio on fuel consumption and power output was investigated for an air-cooled two-stroke motorcycle engine. The results show that actual fuel consumption can improve by 1-3 for each unit increase of compression ratio over the compression ratio range of 66 to 136.
Too little compression or too much cam duration will cause cylinder pressure to drop which will lower the power output of your engine. Too much compression or too little cam duration and cylinder pressure will be too high causing pre-ignition and detonation. If the engine compression was 301 or something absurdly high the vaporized diesel would combust well before the piston reaches full compression.
It seems like there would be substantial engine damage. The sudden increase in pressure on the piston from premature detonation would likely put a lot of stress torque on the crankshaft. Your problem might possibly be fuel leaking into the cylinders due to a worn needle and seat in the carb allowing fuel to perculate into the intake manifold.
Short of replacing the carb you could put an inline fuel shut-off valve in the fuel line and make sure you turn it off whenever you shut the engine off. Discussion Starter 1 Feb 16 2009. Everyone says that over 10to1 compression is too much for pump gas i have a 1979 350 flat tops w4 v reliefs and 60 cc heads it has 1065 to 1 compression and it seems to run fine on 87 octane.
So why does it run so good if i have so much compression. In the case of diesel engines there is no spark plug and the process of compression itself causes the diesel oil to ignite. As a result the compression required in a diesel engine is very high usually about 350 PSI or more.
This makes the diesel engine much heavier and louder compared to the gasoline engines. However if I open the throttle little bit too early it starts to ping. Its a 99 FLHT SE heads SE forged pistons SE 44mm CV carb SE 203 cam SE ari filter Crane HI-4TC ignition Porker Pipes 1051 compression.
I use regular 91 octane gas. HD mechanic told me that its too much compression and I should use flat top pistons 1001 CP. Did you check the compression releaseit is on the exhaust valve cam lobe.
During the compression stroke about 14 from bdc the exhaust valve should slightly open for 20 degrees or so than close for the completion of the stroke. It is controlled with weights so as the engine reaches about 300 rpms the weights will contract the lobe for the exhaust valve so the engine runs properly and yet below 300 rpms allows some compression to escape so the engine. This is why diesel engines are louder and heavier than gasoline engines they must be strong enough to handle the higher compression.
For an engine to function properly the compression must be right. Too much or too little can cause significant issues and damage internal components in addition to causing the engine not to run correctly. An engine compression test is the most practical way to learn about the mechanical condition of your engine.
Because doing a engine compression test will help you locate. Potential internal problems affecting engine performance. Running rough or losing power there may be a lack of engine compression in one or more cylinders.