12/15/2023 0 Comments Valve and ignition timing diagram![]() Since there isn't a pointer you will have to find and mark a reference on the block. Get some white paint and using a small artists brush paint a small line on the damper. On the front of the engine on the generator side, take a look at the damper. Make sure it's in the firing position with both valves closed and distro rotor pointing to #1 wire. Is #1 plug wire to the right of the vacuum advance on the distributor? Thanks guys.Īs a temporary measure if you want to wait to swap the flywheel around, find exact TDC of #1 using the long screwdriver method or similar. If I decide to relocate the flywheel, I'm guessing that I will have to have the engine turned so that #1 is ready to fire and then put the flywheel on with the timing mark showing in the timing window of the bellhousing. Thanks pont35cpe for pointing out the position of #8 in relation to #1 piston. I have the valve cover off and number one plug out so I can tell when the piston is at top dead center. The engine is not in the car yet, but I don't like the thought of dismantling it again in order to change the flywheel position. Thanks DonMicheletti for pointing that out. ![]() ![]() It never occurred to me that the flywheel could go on six different ways. That meant taking off the rear main bearing and removing flywheel, pressure plate and clutch plate to get at the two bolts on the inside of the bellhousing. In order to put the 38 engine in my 40, I had to change the bell housing and the front motor mounting plate. I purchased the 38 engine minus intake/exhaust and distributor. I'm going to put a 1938 engine in my 1940 Buick Special because the original engine was partly disassembled and then left to rust. This ‘overlap’ helps in better ‘scavenging’ or expelling the remaining exhaust gases from the engine cylinder.By the time I get this engine together, I will know just about everything there is about Buick straight 8s. At this point, both the inlet & exhaust valves remain open for a very short period of time causing an ‘overlap’. when the piston starts to move down the cylinder in the suction stroke. The exhaust valve closes after a few degrees of piston reaching the TDC, i.e. It releases the excess pressure and helps to reduce pumping losses for the piston when it moves up. As the exhaust valve opens just before BDC, it causes some of the pressurized exhaust gases to escape even before the piston starts it’s upwards stroke. The exhaust valve opens before the piston reaches BDC in its power stroke. In the exhaust stroke, the piston again moves upwards pushing the exhaust gas out through the open exhaust valve. The engineers precisely calibrate the actual closing point of the inlet valve in such a way that it coincides with the point where the motion of the incoming charge starts to reverse. At this point, the pressure in the cylinder becomes almost equal to the atmospheric pressure. Hence, the inlet valve is kept open until the piston enters its next upward stroke i.e the compression stroke. If the inlet valve closes at this point, the cylinder will receive less charge than its requirement. Therefore, the pressure in the combustion chamber remains below the atmospheric pressure, while the charge is still moving in the direction of the motion of the piston with high velocity. The entire charge cannot enter the cylinder even when the piston reaches the end of its downward stroke because the opening of the inlet valve is small. This air-fuel mixture (also known as charge) has both mass and motion. This is because the downward movement of the piston creates the vacuum (or negative pressure) in the cylinder and the air-fuel mixture gets filled in the empty space. In suction stroke, the air-fuel mixture or charge gets sucked into the cylinder very rapidly. when the piston starts to move up the cylinder in the compression stroke. It closes after quite a few degrees of piston reaching the BDC, i.e. The inlet valve usually opens few degrees before the piston reaches TDC in its exhaust stroke. Engine valve timing is the most critical process of IC engines. ![]() The timing of the opening & closing of valves is specified in degrees corresponding to the position of engine’s pistons. The engine’s camshaft opens and closes the valves at a specific interval. An automotive engine uses valves for it’s ‘breathing’ (inhale/exhale) process. The engine valves are just like the human nose. Firstly, read here about how the engine valves open & close. ![]()
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