TDC...how the heck...

[Dino]

So I'm trying to figure out where the #1 plug wire goes on my Firecore RTR dizzy.  I know I need to get the #1 piston to TDC but I don't know how.  Everything is installed under the hood minus the radiator.  I don't want to remove too many things if I can help it but will do whatever I need to do.  The damn hardline going from the vapor separator to the carb is hitting one of the studs on the dizzy cap so depending on which direction the plug wire boot points I will probably have to suck up spending hours to fit the damn thing and just get a rubber hose, meaning the alt needs to be pulled yet again.   

The only way I know how to rotate the pistons on this thing is to stick a ratchet on the front...but I don't have a socket that large that will fit.  I removed all the spark plugs but I doubt you can roll this thing by hand right?  So I guess I need to buy a socket?  What size is this monster?

Also when the piston is all the way at the top and the line in the damper lines up with the hole, is that TDC?  I don't have any TDC tools so what do I need to buy to do this right? 

Last one:  When the #1 piston is at TDC, I remove the cap and wherever the narrow end of the rotor points is where the #1 plug wire goes right?

[Dino]

Alright I found out some more.  Looks like I need a 1 1/4" socket so I'll pick that up tomorrow.  Seems a piston stop is the way to do this right so I'll get one of those as well.  If I understand correctly, I screw the piston stop in the #1 cylinder and turn the center of the stop in about 1 1/2".  I rotate the balancer one way until the piston stops, make a mark on the balancer, rotate the balancer the other way, make a mark again and TDC is hallway between the two?

[Cooter]

If all your looking to do is drop in a new distributor, no piston stop needed. If your degrading a cam, then I could see it.
simple way to find TDC. Have a buddy bump engine over with number one plug out and find very in hole. When a gust of air begins to knock your finger out of hole, STOP. Rotate engine rest of way around by hand until line on balancer lines up with "O" on timing tab.

If you haven't ripped your original distributor out yet, even quicker way is to look where number one cylinder. Wire is on cap, remove cap and see how far away Roto button is away from that tower. Bump around till button is lined up near that tower in cap.

[cudaken]

Believe it or not, when finding TDC on Miss Lumpy (68 Road Runner that sat 8 years) while rotating with a breaker bar I could feel the compression with my finger. 

If you want to check and see if your timing ring as slipped, you need the piston stop.

Ken

[BSB67]

Alright I found out some more.  Looks like I need a 1 1/4" socket so I'll pick that up tomorrow.  Seems a piston stop is the way to do this right so I'll get one of those as well.  If I understand correctly, I screw the piston stop in the #1 cylinder and turn the center of the stop in about 1 1/2".  I rotate the balancer one way until the piston stops, make a mark on the balancer, rotate the balancer the other way, make a mark again and TDC is hallway between the two?

But that does not necessarily mean that the #1 cylinder is firing.  The rotor may be pointing at #1 or #6 cylinder.

[Dino]

This stuff can never be easy can it?   

I haven't been able to find the line on the balancer yet, but visibility is limited so it may come in sight when I rotate it.  I wanted to use the piston stop exactly because I had read on here that the outer rim can slip and give a false reading.  It's a cheap tool so I might as well do it right and then mark the balancer for future reference.  Besides, there's nobody around to help me turn it over so I need to do it myself.

I did remove the old dizzy and stuck the new one in the same way, but I can easily check the old one to see where it was pointing as I simply removed it and stuck it in a box.  I hadn't though of simply comparing them.  I did remove all the wiring on that one but I'm sure I have a few pics around that show where they went.

BSB, is there a way to make sure which one it's pointing at?

Thanks guys.

[Back N Black]

You can turn the engine by hand with the plugs out, no problem. Another option is run a couple of wires from the starter relay connected to a push button to crank while finger in number one hole.

[Dino]

You can turn the engine by hand with the plugs out, no problem. Another option is run a couple of wires from the starter relay connected to a push button to crank while finger in number one hole.

When you say by hand do you mean that literally or with a breaker bar and socket?  I have not released the belt tensioner yet thinking it would not turn by me grabbing the pulley anyway.

I'm still a ways away from putting power to the car so that's not an option just yet but good to know at least!   

[Back N Black]

I mean by hand, reach down between the engine and rad, grab the crank pulley with two hands and turn the sucker! 

[Dino]

I mean by hand, reach down between the engine and rad, grab the crank pulley with two hands and turn the sucker! 

No  kidding!  I'll have to loosen the belts then because when I try that now it's not budging at all and all the plugs are out.

[ottawamerc]

Wow you would have to have a grip like superman to spin mine I had to use a socket and ratchet and still there was a good amount of force required to move it even with all the plugs out. Dino if you do install the piston stop please make sure you remove your negative battery cable, I think you said there was now power in your car yet anyways but is you crank the engine with the starter with a stop in there there goes your piston! Only by hand.

Scott

[myk]

Hmmm....I don't get it.  If all you're doing is just replacing a distributor, couldn't you just clock the rotor/shaft on the new dizzy to match the one already in the car, remove the old unit, and then drop in the new one? 

[68 RT]

Hmmm....I don't get it.  If all you're doing is just replacing a distributor, couldn't you just clock the rotor/shaft on the new dizzy to match the one already in the car, remove the old unit, and then drop in the new one? 

I agree with that! 

[Dino]

Hmmm....I don't get it.  If all you're doing is just replacing a distributor, couldn't you just clock the rotor/shaft on the new dizzy to match the one already in the car, remove the old unit, and then drop in the new one? 

I dunno, can I?  I can certainly look at the old dizzy and match the new one to it.

Wow you would have to have a grip like superman to spin mine I had to use a socket and ratchet and still there was a good amount of force required to move it even with all the plugs out. Dino if you do install the piston stop please make sure you remove your negative battery cable, I think you said there was now power in your car yet anyways but is you crank the engine with the starter with a stop in there there goes your piston! Only by hand.

Scott

Yep, no power to the car and all the plugs are out.  This baby ain't doing the vroom vroom today!   

[Cooter]

If all your looking to do is drop in a new distributor, no piston stop needed. If your degrading a cam, then I could see it.
simple way to find TDC. Have a buddy bump engine over with number one plug out and find very in hole. When a gust of air begins to knock your finger out of hole, STOP. Rotate engine rest of way around by hand until line on balancer lines up with "O" on timing tab.

If you haven't ripped your original distributor out yet, even quicker way is to look where number one cylinder. Wire is on cap, remove cap and see how far away Roto button is away from that tower. Bump around till button is lined up near that tower in cap.

Hmmm....I don't get it.  If all you're doing is just replacing a distributor, couldn't you just clock the rotor/shaft on the new dizzy to match the one already in the car, remove the old unit, and then drop in the new one?  

[Dino]

I removed the old dizzy months ago so I have no clue which wire it was pointing to.  I have pictures that show where the wires were on the cap but without knowing where the rotor was pointing to that's not going to do me any good.  Of course no parts stores around me even have a piston stop so now I have to order one.

Is this one alright?

http://www.ebay.com/itm/TDC-Piston-Stop-Top-Dead-Center-Stop-Tool-/121351588500?hash=item1c411e4a94&item=121351588500&pt=Motors_Automotive_Tools&vxp=mtr

[Troy]

I use a "remote" switch to bump the starter.  Very cheap and I don't have to keep climbing in and out of the car. I have a piston "stop" that actually has a spring and a gauge so you can see it rise and fall. Normal stops actually stop the piston so you'd want to be hand cranking. I use a long breaker bar and socket for that. In the old days, I used a screwdriver while someone else cranked. Super simple idea that works fine - until you get it cocked in there sideways! With the plugs out you can definitely hear the escaping air of the compression stroke - or you can cover the hole with a finger and it will get pushed off.

The distributor itself can be in any position - just make sure the #1 wire is pointing to the post that your rotor is on when #1 is at TDC. Ideally, if you have a vacuum can, it is toward the engine facing slightly forward and there's enough room to rotate it to adjust the timing. FYI - #6 will also be at TDC at the same time (just on the exhaust stroke) so if it's easier to reach then use it. I set the timing using the #6 wire fairly often since the timing mark on the crank will be at the same location (two camshaft revolutions per crank revolution).

Troy

[firefighter3931]

Dino,

You don't need a piston stop to get the emgine at TDC.  The procedure outlined above using the piston stop is how you check indexing on the harmonic balancer. 

-Pull all the plugs
-Rotate the engine so that the timing mark lines up the zero mark on the timing cover tab
-Check to see if #1 piston is at the top of the bore. If it is....you're at TDC. You can use a small piece of wire through the sparkplug hole to feel for the piston. If the piston is not up top....rotate the engine 360* and check again.
-Once you've set #1 to TDC install the distributor and clock it so that the vac advance is paralell to the front of the engine....this will allow for for/aft movement to adjust the timing.

* I like to advance the timing to 15* BTDC then install the distributor with the rotor lined up at #1 on the cap. This gives you your initial timing allready dialed in and makes the engine easier to fire.


Ron

[myk]

Dino,

You don't need a piston stop to get the emgine at TDC.  The procedure outlined above using the piston stop is how you check indexing on the harmonic balancer. 

-Pull all the plugs
-Rotate the engine so that the timing mark lines up the zero mark on the timing cover tab
-Check to see if #1 piston is at the top of the bore. If it is....you're at TDC. You can use a small piece of wire through the sparkplug hole to feel for the piston. If the piston is not up top....rotate the engine 360* and check again.
-Once you've set #1 to TDC install the distributor and clock it so that the vac advance is paralell to the front of the engine....this will allow for for/aft movement to adjust the timing.

* I like to advance the timing to 15* BTDC then install the distributor with the rotor lined up at #1 on the cap. This gives you your initial timing allready dialed in and makes the engine easier to fire.


Ron

Ron, what about the drop-in method I mentioned above?  Would that have worked if Dino still had his old distributor installed?

[BSB67]

-Rotate the engine so that the timing mark lines up the zero mark on the timing cover tab
-Check to see if #1 piston is at the top of the bore. If it is....you're at TDC. You can use a small piece of wire through the sparkplug hole to feel for the piston. If the piston is not up top....rotate the engine 360* and check again.
-Once you've set #1 to TDC install the distributor and clock it so that the vac advance is paralell to the front of the engine....this will allow for for/aft movement to adjust the timing.

If the timing mark is at zero on the timing tab, the #1 piston WILL be at TDC.  And of course, if you rotate it another 360°, it will still be at TDC.

What he needs to determine is if it is on compression or overlap.

[Cooter]

If all your looking to do is drop in a new distributor, no piston stop needed. If your degrading a cam, then I could see it.
simple way to find TDC. Have a buddy bump engine over with number one plug out and find very in hole. When a gust of air begins to knock your finger out of hole, STOP. Rotate engine rest of way around by hand until line on balancer lines up with "O" on timing tab.

If you haven't ripped your original distributor out yet, even quicker way is to look where number one cylinder. Wire is on cap, remove cap and see how far away Roto button is away from that tower. Bump around till button is lined up near that tower in cap.

Hmmm....I don't get it.  If all you're doing is just replacing a distributor, couldn't you just clock the rotor/shaft on the new dizzy to match the one already in the car, remove the old unit, and then drop in the new one?  

[six-tee-nine]

If you rotaded the crank for about 50 times its easy to know when the #1 piston is at tdc but you still need to know how the positoin of the valves of the #1 cilinder.

If you really are unsure, pull the valve cover so you can see when the valves are closed.

Normally the 0 mark on the balancer should give you the correct position anyway

[Dino]

The mark on the balancer is a split right?  I just picked up the socket so I'll give it a spin tonight and see what I can find.  As it sits now, I don't see any marks.

[firefighter3931]

-Rotate the engine so that the timing mark lines up the zero mark on the timing cover tab
-Check to see if #1 piston is at the top of the bore. If it is....you're at TDC. You can use a small piece of wire through the sparkplug hole to feel for the piston. If the piston is not up top....rotate the engine 360* and check again.
-Once you've set #1 to TDC install the distributor and clock it so that the vac advance is paralell to the front of the engine....this will allow for for/aft movement to adjust the timing.

If the timing mark is at zero on the timing tab, the #1 piston WILL be at TDC.  And of course, if you rotate it another 360°, it will still be at TDC.

What he needs to determine is if it is on compression or overlap.

Correct....it needs to be on the compression stroke with #1 firing.


Ron

[firefighter3931]

The mark on the balancer is a split right?  I just picked up the socket so I'll give it a spin tonight and see what I can find.  As it sits now, I don't see any marks.

Yes, there should be a groove on the balancer. Use some white paint to make the mark easier to see when you go to time the engine. 


Ron