How To Verify Top Dead Center On An Assembled Engine (SBC)

today's video is going to be how to verify top dead center or zero on an assembled engine to do that you use a piston stop that you can purchase at the local auto part store it looks something like that or in my case I took the porcelain out of old spark plugs and used hinge pins to make a piston stop the idea behind the whole thing is you want to stop the Piston at the same point on both sides of top dead center and mark it on the balancer and then top dead center would be halfway between the two points mark it on one side mark it on the other side and then halfway is top dead center to get started the first thing that you would do would be to unhook the battery if the engine's still in the car I always remove all the spark plug so the engine will turn over easily you want to back off the rocker arms on the number one cylinder so that the valves cannot open at all if you don't know that your piston is at top dead center if it's on a running engine you can set the pull the distributor cap and rotate the engine until it's firing on number four and that would put the Piston at the bottom of the stroke so the piston stop won't hit it as you're screwing it in you take the piston stop screw it in the number one spark plug hole I'm going to rotate the engine clockwise slowly until it stops when it stops you take a marker or a pen and mark the balancer where your timing mark says zero then you turn the balancer in the other direction almost a full turn slowly until it stops again then you're going to Mark the balancer with the pen at zero then turn the balancer on the other direction a little bit and screw the piston stop back out and turn the balancer up to where you can see both of your marks then you would get a flexible tape measure and measure the distance between the two marks I'm coming up with five and a quarter divide that into 2 and 1/2 for five and then an eighth of an inch for a quarter it be 2 and 5/8 you take your pen or marker and mark it at 2 58 and that would be where top dead center is at on the zebra Mark that we were using to Mark the other two marks with you line that up to zero and as you can see this engine here the Mark was right where it's supposed to be it's very important to do this if your timing is off you could have serious detonation problems if it's way too much Advanced or you could be losing a lot of horsepower and torque if it's too much on an 8 in balancer 2 in is approximately 30° so if you're off only a half of an inch that would be approximately 8° out if you had your timing set at 38° and you were 8° out on the high side that would be 4 6 and that would be way too much if it was on the other way and set at 38 it would only be 30 and you would be losing a lot of horsepower and torque by not having enough advance in your engine that's going to be all for today thanks for liking and subscribing and I'll see you in the next one

Channel: Brian Summers

Views: 8,597

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Id: TDfqYD5Xt60

Length: 5min 19sec (319 seconds)

Published: Sat Dec 23 2023