Top Dead Center Question

[littleblueranger]

I understand what all I need to do in order to get the motor to TDC. What I dont understand is the marks I need to line up. It seems like everything I read says sumthing diffrent. Between the oil pan and engine under the crankshaft pulley is a little metal tap in an arrow shape pointing down, is that the alignment mark that needs to line up with the missing tooth? Im so confused.

 

[Big Jim M]

Why would you need to know? What are you doing that might require to KNOW where tdc is?
Once I put an engine together it is proper and stays that way throughout it's lifetime.
So tell us where you are in this and what you are doing?
Big JIm

 

[littleblueranger]

Iam trying to replace the cam synchronizer. I dont want to just put the new sensor in the way the old one was. I need to tdc the motor so I can align the sensor up accordingly.

 

[Big Jim M]

Ok

Iam trying to replace the cam synchronizer. I dont want to just put the new sensor in the way the old one was. I need to tdc the motor so I can align the sensor up accordingly.

Whatcha do there is to make a mark on the engine with a knofe or something thin that aligns up with a certainpart of the sensor. Then you install the new one to the exact place on that mark.
That will be far closer than trying to get TDC lined up perfectly from the outside of the engine.
That's the way everyone else does the swap and it works fine.
Big JIm

 

[TomB1269]

Whatcha do there is to make a mark on the engine with a knofe or something thin that aligns up with a certainpart of the sensor. Then you install the new one to the exact place on that mark.
That will be far closer than trying to get TDC lined up perfectly from the outside of the engine.
That's the way everyone else does the swap and it works fine.
Big JIm

Jim, in a previous post he's already pulled it and did not mark it...... Its tough but you'll need to line it up set it, try it, and do it again until you get it. You can feel for TDC on piston with screw drive or better a firm small plastic rod.

 

[Big Jim M]

Ok then

Jim, in a previous post he's already pulled it and did not mark it...... Its tough but you'll need to line it up set it, try it, and do it again until you get it. You can feel for TDC on piston with screw drive or better a firm small plastic rod.

I'd install it about in he middle of the possibilities.. Then take it for a drive to see how it behaves. Then I'd move it a bit and drive it again.. And on and on till I felt it was doing it's best without ratteling at part throttle hiway speeds.
This method will get you closer than the damn screwdriver will.
Big JIm

 

[Rearanger]

littleblueranger, there is no "exact" setup position for the sycronizer although I don't know how the factory initially sets it up. However Big Jim is right in that you'll probably need some trial and error. In your case I would recommend getting the alignment tool. Getting as close as you can to #1 piston TDCC will help and using a screwdriver or other probe will definately make it easier. You'll need to carefully observe the highest point of piston travel with the probe. Then using the sensor alignment tool the sensor will be "close" at 75degrees counterclockwise from the engine centerline. Note that you're trying to engage the teeth of the gears at the exact position so you'll be a tooth or two off at max. Any adjustment will be getting the next tooth in it's postion with the mating tooth.

 

[littleblueranger]

I got everything reinstalled and started the truck. It idles rough and misses at slow speeds, but as I speed up it somewhat smooths out. Is the timing just off? Can I twist the cam sensor around to adjust this?

 

[Big Jim M]

YEp!

I got everything reinstalled and started the truck. It idles rough and misses at slow speeds, but as I speed up it somewhat smooths out. Is the timing just off? Can I twist the cam sensor around to adjust this?

TWIST is not a word I'd use. But it will suffice. So turn the engine off and twist the thing with the outside moving about 1/8th of an inch. Then start and drive... It'll be either better or worse! If worse then twist it 1/4 inch back the other way. If better then move it another 1/8 th thataway. And so on until it starts running worse and then go backward again to the best overall performance.
Big JIm

 

[JP02XLT]

They do make a tool you can rent from Advanced Auto to properly align it, I think the Doorman replacement units come with the tool.

JP02XLT

 

[littleblueranger]

I moved it a tad bit counter clock wise and drove it around, perfect, better than before actually. Tho now that I said that...........

 

[fourwheelford]

If you install the syncro one tooth off will it run like complete garbage or would it be minor like slight power loss? Say the tooth is in the center of the gap and it gets installed so the tooth is to one side or the other of center how would that effect the operation? I have retarded a distributor vehicle to far before and caused a loss of power and that is what it seems like I may have done on my truck with the syncro. It started and ran fine without a cel so I figured I did it right but now im second guessing myself.

 

[Big Jim M]

If it is one tooth out it prolly won't run at all... Pop and crackle maybe but not run.
Big JIm

 

[fourwheelford]

Ok so there is no margin for error if its out you know it, damn I was hoping I was on to something that may be causing my problems.