drawing a blank and need some help

BgBlDodge

BgBlDodge

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May 7, 2007
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Getting ready to reinstall my p-pump and need to find TDC. If I'm correct I rotate the engine clockwise (looking at the front of the engine) until the intake valve closes and the exhaust valve just starts to open and that will get me close and then I do the drop valve method to find true TDC.

Now for the drop valve method I go and tighten the intake valve adjuster 4 turns past 0 lash and rotate the engine clockwise until the piston touches the valve and mark the dampner. At that point loosen the intake valve back up and then tighten the exhaust valve 4 turns past 0 lash and rotate the engine counter clockwise until the piston touches the valve and mark the dampner. From what I've read the marks should be roughly 4" apart from each other and the dead center between those two will be true TDC.

Sound right to yall? I know it's a rookie question but my mind isn't grasping this concept this morning.
 
anyone? I'm ready to install the pump but am unclear mainly on the drop valve method.
 
Ummm. There is a plug thingy on the back of the cover, when the engine hits TDC the plug pushes into the hole in the cam gear......
 
Its easier to use the screw driver method. pull a long skinny screwdriver down the injector hole, turn the crank clockwise (when looking from the front) and when the intake valve closes the screwdriver will start pushing up as it comes up on the compression stroke. as it comes up make sure you are holding or guiding it to keep it up right, cuz if not it gets jammed between the slope of the piston dome and the head and it will bend the screw driver, so i always keep one hand on it to make sure it stays vertical and doesnt get jammed up. when it gets to the top and just stops moving, mark the damper at whatever indicator you are using. you will be able to turn the motor a little bit more as the piston dwells at TDC, when it starts to drop again make another mark. in between those is TDC.

it usually takes me about 2-3 minutes to get it at TDC and its close enough this way that its not gonna make a difference. it will get you to within a half a degree of timing. you can get a little more accurate with a dial indicator if you really wanna get technical.
 
I'll probably end up doing that since I'm slightly confused on the drop valve method. Just wanting to make sure I do something right and accurate for a change on this truck. Thanks.
 
I did just what TJ explained and it worked just fine for me. I figured im within a degree or so which is just will work for what im doing.
 
getblown5.9 said:
Its easier to use the screw driver method. pull a long skinny screwdriver down the injector hole, turn the crank clockwise (when looking from the front) and when the intake valve closes the screwdriver will start pushing up as it comes up on the compression stroke. as it comes up make sure you are holding or guiding it to keep it up right, cuz if not it gets jammed between the slope of the piston dome and the head and it will bend the screw driver, so i always keep one hand on it to make sure it stays vertical and doesnt get jammed up. when it gets to the top and just stops moving, mark the damper at whatever indicator you are using. you will be able to turn the motor a little bit more as the piston dwells at TDC, when it starts to drop again make another mark. in between those is TDC.

it usually takes me about 2-3 minutes to get it at TDC and its close enough this way that its not gonna make a difference. it will get you to within a half a degree of timing. you can get a little more accurate with a dial indicator if you really wanna get technical.
Click to expand...



Finally an easy to understand method.
Thanks Tj
 
Thats how I do it as well.


getblown5.9 said:
Its easier to use the screw driver method. pull a long skinny screwdriver down the injector hole, turn the crank clockwise (when looking from the front) and when the intake valve closes the screwdriver will start pushing up as it comes up on the compression stroke. as it comes up make sure you are holding or guiding it to keep it up right, cuz if not it gets jammed between the slope of the piston dome and the head and it will bend the screw driver, so i always keep one hand on it to make sure it stays vertical and doesnt get jammed up. when it gets to the top and just stops moving, mark the damper at whatever indicator you are using. you will be able to turn the motor a little bit more as the piston dwells at TDC, when it starts to drop again make another mark. in between those is TDC.

it usually takes me about 2-3 minutes to get it at TDC and its close enough this way that its not gonna make a difference. it will get you to within a half a degree of timing. you can get a little more accurate with a dial indicator if you really wanna get technical.
Click to expand...
 
getblown5.9 said:
Its easier to use the screw driver method. pull a long skinny screwdriver down the injector hole, turn the crank clockwise (when looking from the front) and when the intake valve closes the screwdriver will start pushing up as it comes up on the compression stroke. as it comes up make sure you are holding or guiding it to keep it up right, cuz if not it gets jammed between the slope of the piston dome and the head and it will bend the screw driver, so i always keep one hand on it to make sure it stays vertical and doesnt get jammed up. when it gets to the top and just stops moving, mark the damper at whatever indicator you are using. you will be able to turn the motor a little bit more as the piston dwells at TDC, when it starts to drop again make another mark. in between those is TDC.

it usually takes me about 2-3 minutes to get it at TDC and its close enough this way that its not gonna make a difference. it will get you to within a half a degree of timing. you can get a little more accurate with a dial indicator if you really wanna get technical.
Click to expand...


thats what i do except i use a 1/4" drive extension to put in the injector hole and set my dial indicator up on the end of the extension. Its fast and accurate
 
I wouldn't mind using my dial indicator if I had a good way to hold it down. Guess I need to go invest in a magnetic holder.
 
BgBlDodge said:
I wouldn't mind using my dial indicator if I had a good way to hold it down. Guess I need to go invest in a magnetic holder.
Click to expand...

Just rest your hand on the valves and hold it....:poke::poke:


Not like it matters anyway Tyler....you're never breaking 500hp:D
Chris
 
Tyler,

Remember for the purposes of setting the timing on the truck once the pump is installed. You need to rotate the crank a full rotation after you mark TDC using the above method.

You wouldn't want to set your pump up to inject fuel between the valve opening events...

unless you want to make less than 500 hp:hehe:
 
Soooo mark TDC using the screwdriver method and then rotate the damper one full revolution back to TDC? Why would that make a difference? I understand not wanting to inject during valve opening but isn't TDC, TDC? I don't need to time the engine, just need TDC. Pump is pinned at 24*. Or am I missing something? Wish I wouldn't have been lazy and marked it when I had the front end off.
 
BgBlDodge said:
Soooo mark TDC using the screwdriver method and then rotate the damper one full revolution back to TDC? Why would that make a difference? I understand not wanting to inject during valve opening but isn't TDC, TDC? I don't need to time the engine, just need TDC. Pump is pinned at 24*. Or am I missing something? Wish I wouldn't have been lazy and marked it when I had the front end off.
Click to expand...

Gear lash.
 
your engine is a four stroke. crankshaft rotates twice for every pump revolution. So your piston will be at TDC twice with each pump revolution.

If you leave the crank at tdc (as found above) and install you pump (pinned at 24 degrees) you will have a hard time getting it started as you will be injecting fuel while the exhaust valve is open and trying to burn it as the intake valve opens up.

I understand you may have just been asking about tdc of an engine, but I didn't want you or others reading this thread to follow the directions above, then do the next logical thing and install your pump, and then try to start it and wonder why it doesn't run. $.02
 
If you do it with the screw driver method I listed you do not need to rotate it, because you are finding TDC on the compression stroke.

If you use the valve drop method, thats finding TDC on the exhaust stroke (between exhuast close and intake opening), so one revolution of the crank (half revolution of the cam) puts the piston back at TDC on the compression stroke.
 
:bang I just reread TJ's post. Yes, if you find TDC on the compression stroke like he originally stated then you are good. If you however find it on the exhaust stroke, then you need to rotate the crank 360 degrees before installing the pump.
 
OK. Now I understand where you are coming from. For a while I was scratching my head going "whats he talking about." Ya, I'm gonna find TDC using the drop screwdriver method LOL
 
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