Dodge V-8: Finding Top Dead Center and Piston #1

[toddabney]

Sent: 9/11/2008 3:11 PM

hello all, well while trying to fix a no spark issue i changed many things the last was  the pick up coil in the distrubitor. i took pictures of "before"with the cap off so when i put the diff back in it would be the same.well when i went to put it in, the recieving slot down in the engine was going north and south instead of being east and west as it was when i took the disturbter out. so i changed the slot angle with a big screwdriver, said a prayer and tried to start it.i heard a back fire from down under and shut it off.   so how do i find top dead center? where is number one pistion? any advice would be great.thank you,todd

[denisondc]

 
Sent: 9/11/2008 6:48 PM

The number one cylinder is the frontmost on the drivers side. They are #1 3 5 7, (front-to-rear), on that left bank. Those on the passenger side (right bank) are #2 4 6 8, also front-to-rear. This is true for all mopar V8's I believe.
Its not too hard to find t.d.c on cylinder #1... but by finding it on cylinder #6, which is halfway along in the firing order. (1- 8- 4- 3- 6- 5- 7- 2 for 440's and probably for 318's too). Cylinder # 6 is just easier to reach & poke a wooden dowel rod into, than is cylinder #1. Unfortunately you wont know if it is t.d.c between the compression-to-firing stroke, or t.d.c. between the exhaust-stroke-to-intake-stroke though; and there isnt an easy way to tell. If you dont want to pull off a rocker cover to look at the valves, or put an air chuck on a fitting screwed into the spark plug hole, then you will have to look at the rotor on the distributor. All-other-things-being-normal, it would either be pointing to the terminal on the distributor cap that is for the plug wire to cyl #1, or it will be pointing to the terminal for the plug wire to cyl #6. ....A 50-50 chance of getting it right.
BUT...you may have another problem. You said you turned the distributor drive gear down inside the front of the engine? I only know 2 ways for that drive gear (the thing with the slot in it) to rotate. One is if the engine is rotated - which would turn the camshaft of course, and which would then turn that gear with the slot. The other is if the gear is pulled up so it is out of contact with the driving gear (at the front end of the camshaft). This also means the shaft that turns the oil pump is pulled up, since the gear and the oil pump drive shaft are pinned together. You could push the gear back down facing in a different position - but when you reinstalled the distributor, its shaft and the rotor on that shaft would now be pointing other than where it needed to. [I think there are 18 teeth on the gear, so there are 17 ways to have it wrong].
This is not itself a big problem, you could just rotate the distributor to line up the plug wires properly, or move the plug wires to different terminals on the distributor cap, to line up with the 'new' position of the rotor. (I have done both of these in my time & have encountered both confusing situations in working on vintage engines.)
The -problem- would be knowing for sure whether the inner rotor of the oil pump was still being turned by the bottom end of the shaft. It would be nice to think that pushing the shaft/gear back down into full contact with the cam gear, would mean its bottom end had slid into the splines of the inner rotor of the oil pump. And I -think- if you were able to fully install the distributor, it would mean the gear and the shaft driving the oil pump were fully seated, and that the oil pump would surely turn.
Luckily on a 440 the oil pump is external to the block. You can unbolt the lid to the pump and check whether it is turning when someone cranks the engine. If you take that lid off, you will need a new "O" ring for reassembly, and you will need to keep the inner/outer rotors from sliding off and dropping into the dirt. You also Really Do want to avoid having the two moving parts of the oil pump bang against each other and raise a burr on the shiny machined surfaces. It would be easier to start the engine and see if the oil pressure came up.
Good Luck...
P.S. When #1 is on t.d.c. the slot should be lined up pretty much parallel to the front-to-rear centerline of the engine.

[toddabney]

Sent: 9/11/2008 9:22 PM

hey denison,thank you for the save...i always use a compresion guage to find what cylinder is "coming up"i turn the engine over by hand ,just when pressure starts to show on that cylinder i stop and then turn it till it lines up with the timing mark.that is how i do it on subarus.that should work with the 440,don't you think? then just adjust the slot to line up with the rotor to point to number one on the cap and it should be good...right? when i turned the bottom slot with the screw driver it wouldn't go to the left but did the other way.i gently turned it and it would go up just a hair and then drop down.hope i can stumble through this as the rig is sitting crossways in the driveway when it decieded not to start.  thank you again. todd

[denisondc]

Sent: 9/12/2008 4:15 AM

Turning the engine with a compression gauge in the #1 cylinder sounds good. I admit I never tried that. The only problem might be the amount of sliding friction in a v8 being high enough that you cant feel the compression very well. If you had the other spark plugs out - that might make it easier to tell.
Yes, the distributor drive gear would be about impossible to turn to the left, (clockwise I think), but would turn to the right (clockwise) because in that direction the gear would rise up on the teeth of the driving gear on the camshaft. But --I think-- the distance it should need to slide up before the teeth werent connected wold be perhaps an inch.

[toddabney]

Sent: 9/12/2008 8:20 PM

well, bada bing(whatever that means) got her going!!! using the compresion guage worked great to find number 1.it was hard turning it over but when i saw the neddle move a little i stoped and then got over where i could see the timing marks i turned it over till the marks lined up and bango..she fired right up. i lined the line on the harmonic balancer with a hole through the timing plate.i am guessing that is top dead center.i plan on cleaning that area and setting the timing tommorow.i can't seem to find any pictures of the timing plates ect. but will keep looking.thank you again denison. "you the man"  todd

[rcaircraftnut]

That timing mark should be TDC, however, Mopars have a bad habbit of allowing the dampenner to rotate on the rubber ring its mounted to.  So sometimes the marks can be off by quite a bit. Sounds like yours was still very close. Glad to hear it.