Camshaft Install - #6 Cylinder - FINDING TDC/COMPRESSION 2f 1978 FJ40 (1 Viewer)

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Ok.. need to put camshaft back in.

Need to find TDC on #6 CYl on the COMPRESSION STROKE.

I can find TDC on this cause the piston is at the TOP, but - as I have the rocker valves off and DIZZY out .. is there a good way to know if this is on compression stroke?
What would the #1 CYL be at - perhaps?

See image from ENGINE MANUAL..

need help finding #6 Cyl at TDC/COMPRESSION. See Fig 3-85

Thanks
eaj71
Camhaft.jpg
 
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I might be overthinking this... is this correct:?


Correct:
-- #6 PISTION should be at the TOP of block ... while the TDC mark is ALIGNED in the WINDOW. = COMPRESSION STROKE

Incorrect
-- #6 Piston is NOT AT THE Top of the BKLOCK , but still at TDC as aligned in the WINDOW= EXHAUST STROKE
 

middlecalf

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Correct:
-- #6 PISTION should be at the TOP of block ... while the TDC mark is ALIGNED in the WINDOW. = COMPRESSION STROKE
And the rocker arms for both the valves for #6 will wiggle a bit cuz’ the valves are closed on compression from spring pressure. If not then your not at TDC for #6.
 
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...but I’m not sure what you are saying... is what I said correct above and my rockers arm are off

Could I ask you to clairify just a bit?
 

Steamer

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In my opinion, the manual is wrong. Yeh, I said that.

Where it says, “Set No. 6 piston to TDC/compression”, the cam is not yet installed. When the cam in not installed, there is no compression or exhaust stroke. There is only TDC. How the cam is inserted will determine whether it is on compression or exhaust TDC.

Don’t worry where the pistons are. If you simply make the marks match up, you cannot be wrong.

When the marks match up, by circumstance the # 6 cylinder will wind up on TDC compression as pointed out in the “Note”
 
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Steamer. You are a bold man

can anyone verify or concur

it seems to make sense. But mr toyoda said it twice. #6 on compression /tdc
 

Steamer

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Yep, it can be a bit of a brain teaser but if you think it through……

Keep in mind, #1 & #6 pistons move together. When the flywheel’s TDC line mark is on the pointer, #1 & #6 pistons are both at TDC. One will be on compression and one on exhaust. How you insert the cam determines which one is on which stroke.

If you rotate the crank to the TDC flywheel mark, you could insert the cam so the marks match up or you could actually insert the cam so the cam mark is 180 degrees out. Not practical but it would be correct. And then just rotate the crank 360 deg, and the marks will match back up.
 
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I don’t have the head off. But as #1 pistiom goes down on the exhaust at the same time #6 comes up on compression?

right ?
 

73FJ40

After another night of rust removal!
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I don’t have the head off. But as #1 pistiom goes down on the exhaust at the same time #6 comes up on compression?

right ?
Wrong. You don't seem to understand the concept of a four-stroke cycle engine. 1. intake down 2. compression up 3. power down 4. exhaust up. Repeat.

Intake sucks air/fuel in from the intake manifold. Exhaust pushes gas out through the exhaust manifold.

Steamer is right: No. 1 and No. 6 are identical in stroke, but one is moving up on the compression stroke to TDC, and the other is moving up on the exhaust stroke to TDC.

Stop over thinking this until you read up on four stroke cycle engines.
 
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I think that what is being missed here is that without the cam being installed you only have piston position and nothing more because there is no compression or anything else. So #6 and #1 pistons will both be at top dead center, period. Once the cam is installed and the timing marks aligned will put the cam and crank in sync. End of story.
 

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