81 F250 4x4. Stock pistons. Has RV cam and new timing set. I have the cam gear pointed down while the crank gear points up. So this puts the engine at 0 degrees @TDC is this right ? I havent got my distributor put in yet but when i do, do i put in the same direction as i pulled it out even though i have upgraded timing set and cam ?

 

When the marks are lined up, that is not necessarily #1 TDC. I know it's not on a small Chevy. I would do the finger over the sparkplug hole trick or take the pass side valve cover off and watch the valves to make sure you are at TDC at #1.

Since you moved everything around to line up the gear marks, your dist is not going to go back in the way it came out. Once you get the engine setting at #1 TDC, you need to find #1 sparkplug wire, and make sure the rotor is pointing to it when it's all said and done.

 

I have heard of the finger over the #1 spark plug what is that for and what does is do ?

 

Assuming it's been installed correctly. Valve timing is different than ignition timing as you know, there should be a quick way to check on your motor, depending on the firing order, a specific set of valves will be opening/closing exactly at #1 piston TDC compression stroke, if the gears and cam and everything is all lined up right. On a Y block, for example because I'm familiar with that, the #6 cylinder exhaust valve should have just closed and the intake valve just start to open, exactly when the "0" damper mark passes the pointer. That means the timing chain isn't stretched, jumped time, or installed wrong.

Stabbing the distributor correctly is simply a matter of first lining up the #1 piston at TDC, on its compression stroke, and then ensuring that the distributor rotor points to the #1 terminal on the distributor cap. This can be a little tricky to finagle till ya get the hang of it. Holding your tongue just so is often required.

A thumb over the #1 spark plug hole while rolling the motor over with a breaker bar ensures that you're actually on #1 piston TDC compression stroke... and not #1 piston TDC exhaust stroke. Big difference! You can feel the air escaping on the compression stroke. Installing a distributor 180° out is a common error.

This is why you'll sometimes see the wires installed out of sequence by a previous owner. The #1 plug wire terminal on the distributor is arbitrary, it can be any one you like so long as the firing order is maintained. So rather than pull the distributor again, peeps just move the wires on the cap around. The distributor doesn't care, but it must be able to be turned to and fro without physically hitting anything and interfering with setting the initial timing.

 

#1 piston comes up twice and the timing marks on the damper line up twice for every cycle the engine makes. It's a 4 cycle engine, the crankshaft goes around twice for each complete cycle.

So if you bring the marks around on the pointer till they line up, you have a 50 50 chance of being wrong and in the wrong part of the cycle. If you line up the dist to the wrong part of the cycle, it won't run it's what they call putting the dist "180 degrees out".

The only way to make sure you are on the correct part of the cycle is to take the sparkplug out and crank it around till air starts pushing your finger off the hole. This means both valves are shut and the piston is coming up getting ready to fire. This is the part of the cycle that you want.

The other part of the cycle is the exhaust stroke, the exhaust valve will be open and it will not have the same pressure to push your finger off the hole.

 

Yes.
If the Cam and Crank dots are "pointing at each other" (crank dot at 12 o'clock and Cam dot at 6 o'clock) the #1 cylinder is on the compression cycle. You can install distributor so the rotor is pointing the #1 cylinder.


If it was on the exhaust stroke the Crank dot would be at 12 o'clock and the Cam dot would be at 12 o'clock.

 

[QUOTE=CountryBumkin;17282858]Yes.
If the Cam and Crank dots are "pointing at each other" (crank dot at 12 o'clock and Cam dot at 6 o'clock) the #1 cylinder is on the compression cycle. You can install distributor so the rotor is pointing the #1 cylinder.

So just for clarification which way would the advance timing be oriented ?

 

CB, you got it! I was wondering what the others were reading about cam/crank dots and TDC?

[QUOTE=Tartersauce53;17282959]I don't under stand what you are asking here?
If the cam/crank dots are lined up right it is at TDC just drop the dist. in so rotor points to #1 on the cap. Remember the rotor will spin some as it drops down.


Are you talking about the vacuum advance can on the dist.? If you have a book showing firing order etc. it should show how it points and where#1 is on the cap.
Dave ----

 

Gottt it i was over thinking it ! Hahaha thanks yall

 

My vacuum advance nipple points to 7:00 o'clock. The same on my 79 mark V. Hope this helps

 

thanks bud

 

[QUOTE=Tartersauce53;17282959] If you mean advancing the "Cam valve timing" you can not do that by just moving the cam dot one tooth forward or back from 6 o'clock. One tooth movement is too much. If you want to advance the Cam valve timing, you would need to buy a special cam gear (or timing chain/gear set) that has multiple notches (for the crank keyway) machined in several places for advancing or retarding (the notches are like a half tooth offset).


If your talking about advancing the "ignition timing" by rotating the distributor - then that has been discussed.

 

I just want to make sure nothing happens valves and my pistons because some is out of time

 

That will not happen.
Old school stock American v8's never had issues of valves & pistons being in the same place at the same time.
Unless you run it at vary high RPM and even then might not.
I have had chains fail driving down the high way with no issues.


Line the dots up like the paper that came with the chain set or the book you are using and you will be good.
Dave ----

 

It sounds like you replaced the camshaft (not just the timing gear/chain set).


If so, you installed new lifters and had the rocker arms off, and your going to need (want) to check the adjustment.