[webcat]

i'm trying to find TDC power stroke!
i hollowed out a old spark plug and ran a hose from it to by my drivers seat and then cranked the engine (coil disabled) put my thumb over the hose and it blows air out every time the rotor comes up on the #1 spark plug wire , so i assume i'm at TDC power stroke eveytime the rotor is at #1
I was thinking i had this figured out before and i thought that TDC power stroke was every other time the rotor contacted #1 spark plug wire and the oppisite every other rotor contact with #1 was TDC intake stroke

In the picture below is how i thought it worked!
Is this picture correct?

 

[Munken]

It all happends in 2 revolutions. You have the TDC right. :thumbup:

 

[Big_kid]

http://www.animatedengines.com/otto.shtml

 

[webcat]

Thanks guys
[youtube][/youtube]

 

[webcat]

I guess what i'm really trying to figure out is for every one complete revolution of the harmonic balancer , how many revolutions does the distributor rotor turn ?

 

[astro355]

I guess what i'm really trying to figure out is for every one complete revolution of the harmonic balancer , how many revolutions does the distributor rotor turn ?

The crankshaft turns twice for every rotation of the camshaft meaning that the balancer will turn 1 for every half turn of the rotor in the distributor.

 

[webcat]

I guess what i'm really trying to figure out is for every one complete revolution of the harmonic balancer , how many revolutions does the distributor rotor turn ?

The crankshaft turns twice for every rotation of the camshaft meaning that the balancer will turn 1 for every half turn of the rotor in the distributor.

ok , so that means that just because the rotor is pointing to #1 sparkplug , does'nt mean for sure that #1 piston is at (TDC power stroke)
Its possible for the rotor to be pointing at #1 sparkplug but the #1piston could be at TDC but on the intake stroke.
, every other time the rotor points at #1 plugwire it would be (TDC power stroke) and every other time the rotor points at #1 plugwire it would be (TDC on the intake stroke)
I was confused because i had a old sparkplug that i hollowed out and i put it in #1 bank with a hose leading into my cab and i put my thumb over the hose and cranked the engine while i watched the rotor turn and every time the rotor passed the #1 plug wire it blew psi out and so i thought that it was at (TDC power stroke) every time it blew psi out.
Hey 355 , i'm suprised you hav'nt asked me if i'm writing a book :lol:

 

[01safari]

I think the best way is pull the valve cover and check to see if both valves are closed when the piston is at the top of its stroke. This would tell you for sure. If the intake valve is open, then you need 1 more turn of the crankshaft. :banana:

 

[Gary]

I think the best way is pull the valve cover and check to see if both valves are closed when the piston is at the top of its stroke. This would tell you for sure. If the intake valve is open, then you need 1 more turn of the crankshaft. :banana:

Going to add to this posting.

Watch both valves open and close on number one(both lifters must be on the heel of the cam).......... finger over spark plug hole and feel the piston coming up.........look for -0- on the harmonic balancer........check to see the dizzy's rotor is on number one.

You could fashion a remote starter button with two clips that go on the terminals of the starter and a trigger and some wire or buy one from your local parts store.If you think your going to do lots of work under the hood,might be worth it to permanently install one on the firewall. :think:

 

[Big_kid]

The rotor/distributor rotates 1 time for each turn of the CAMshaft (1:1 ratio). The CAMshaft turns one time for every TWO turns of the CRANKshaft(1:2). The crank has a sprocket on the end, which drives a chain that turns the camshaft. The cam sprocket has twice as many teeth as the crank, so it takes two turns of the crank to make the cam go around once.

If the rotor is pointing to number 1, in a healthy engine the #1 piston is at TDC, and the valves are closed. When the #1 piston is at TDC (top dead center) and the valves are rocking (exhaust closing & intake opening) the rotor should point to #4, directly across from #1 on the distributor cap.

I hope this helps some. I can picture it as plain as day in my head, but my explanation may not appear to be as bright.

 

[astro355]

The rotor/distributor rotates 1 time for each turn of the CAMshaft (1:1 ratio). The CAMshaft turns one time for every TWO turns of the CRANKshaft(1:2). The crank has a sprocket on the end, which drives a chain that turns the camshaft. The cam sprocket has twice as many teeth as the crank, so it takes two turns of the crank to make the cam go around once.

If the rotor is pointing to number 1, in a healthy engine the #1 piston is at TDC, and the valves are closed. When the #1 piston is at TDC (top dead center) and the valves are rocking (exhaust closing & intake opening) the rotor should point to #4, directly across from #1 on the distributor cap.

I hope this helps some. I can picture it as plain as day in my head, but my explanation may not appear to be as bright.

I think what he is getting at is the position of the rotor overall. Regardless, when the rotor is pointing at cylinder #1, cylinder #1 should be at (or very close to) TDC, in a healthy engine.

 

[webcat]

[quote="astro355"}

I think what he is getting at is the position of the rotor overall. Regardless, when the rotor is pointing at cylinder #1, cylinder #1 should be at (or very close to) TDC, in a healthy engine.[/quote]
355 , you already have 3 green sparkplugs :lol:

 

[Hangard]

I like to think of it this way: The rotor turns one-half the engine speed.

For every time the rotor turns to #1 a complete 4 cycles have been done for that cylinder, and as you found the cylinder is coming up on TDC as well.

This is an easy way to verify if the timing chain and sprockets [or gears, or belt, depending on engine] is all in proper working order and aligned properly.

If your hollowed out plug and hose gives you a shot of compression at any other time you will have an engine that does not run. Either the timing has jumped or the distributer has been put in out of order.

The spark gets transferred to the plug for the cyl. when the rotor is aligned, and the cyl needs the spark just a few degrees before TDC as the fuel is in and is compressed, now just a bit of spark and the mix will explode and push the cyl down its bore, moving you along.

 

[astro355]

Webcat, you had better get the idea here. I have never seen some many different ways of saying the exact same thing.

 

[webcat]

Webcat, you had better get the idea here. I have never seen some many different ways of saying the exact same thing.

Yea i got it , its extremely clear now!

 

[Jasen]

Drilling out a plug and putting a tube on it?
Never heard that one :lol: :thumbup:

I just jam a rag in the SP hole good and tight with a screw driver, then bump it over till it POP's.