I need help finding tdc

-
M

MotorHoggGears

Member
Joined
Jul 11, 2019
Messages
8
Reaction score
0
Location
Houston
So I tried with the belt and the fan nothing . I tried with bump start to much of a guessing game for me so I got a harmonic balancer bolt 3/4-16,2 and 2in washer but tdc is a little difficult cause it not lined up on damper and balancer?? Anybody in Houston that can come to me and help or any info really appreciated?
 
What year/displacement engine?
What year/displacement damper?
Is your thimming mark on the passenger side, tin and bolt on OR is it on driver's side and cast into the timing cover
 
I do it two ways, rotate the motor by hand and have someone stick a flat head or something in the drool tube where the plug goes but be careful it can get stuck if no ones holding it once it comes all the way up and the rotor points at the right spot, you got it.

Another way is having the drool tube in place put some toilet paper and crank the motor over slowly quick cranks until the piece of paper flies out due to the pressure of the piston rising to Tdc.

The rotor only points one way at number one here's a picture once you reach that point your good

IMG_0794.GIF
 
I put my finger over the #1 plug hole and bump it until I feel compression. Then I put a big ratchet on the balancer bolt to dial it in. If you need it exact use a piston stop and degree wheel.
 
Well I been trying to line it up with damper and timing chain but it seems like I'm doing something wrong. I wait till I feel compression on my finger and then line it to the dampera cover line up to zero,and then set the rotor to number one spark plug but i get nothing. I was told wait till the intake valve open and close then line it up but still nothing. Any suggestions
 
Feeling compression is rather vague; that just tells you that you are getting close. But true #1 pistonTDC could be as much as 120 degrees further along, and that is what you have to find exactly, irregardless of any other markings. So after you feel the pressure pulse, the piston is gonna be around 1/3 to 1/2 of the way up; continue rotating the crank in the CW from the front,direction until the piston comes up as high as it can go and starts back down, then back it up, back to the top . Sometimes you get lucky and the damper is right on. If not then mark your balancer with a yellow or white paint marker. This is close enough to ballpark your TDC for purposes of aligning the rotor and idling. Later, if the damper is not correctly marked, we can walk you thru marking it properly. Eventually you gotta know where TDC#1/compression is, exactly..
For setting the idle-timing, this is less of a big deal cuz the engine will start anywhere from 5 to 10 degrees retarded to 30 advanced; and can be made to idle at up to 45/50 advanced; you just can't leave it there.
If the rotor is under another tower, then just move the #1 wire to it and follow the others in the firing order.
But if the rotor ends up between towers somewhere, then you may, may have another problem.

Oh wait, I re-read your last post and it seems like this is where we are at.I didn't get it the first couple of times.

Ok then verify that the piston is at the top when the damper is indexed to the TDC mark, and both valves are closed, and that the rotor rotates with the cam. This is 90% of the job. If you got this then the final part is to prove the rotor is under a tower any tower, when a reluctor vane is passing the pole-piece center. Or if points, when the points just barely crack open.
If it isn't then back up the crank until the balancer shows about 15* advanced, Then do it again.
After you get this done, whatever tower the rotor is under will have to be wired to your #1 plug, and the rest follow in the correct firing order 1-5-3-6-2-4, wired in the correct direction CCW IIRC.
If you get this and the cap and rotor are correct, then if the rest of the systems are up to snuff, then it has to start.
Unless the valves ain't closing.
 
Last edited:
Its a good idea to clock the intermediate gear correctly once you find tdc. Its not critical but if your plug wires are loomed they might now have enough slack to move them around.
 
He/we are still back to the original first step. Verify TDC, and the timing marks line up on the damper and timing tab, or make new marks if the ones on the vehicle do not line up.. Nothing else is relivent untill this is verified
 
Ah slantie. I will upgrade my comment to "replace" the distributor drive gear while your at it. I had seen my fair share of those shred themselves. Had a pin shear once and you could not tell by looking at it. The gear was tight on the shaft too. I retimed and it would slip as soon as it started.
As far as TDC, the procedure is the same on anything. Make sure your on the compression stroke then rotate to line up the damper mark to 0.
 
MoparMike1974 said:
As far as TDC, the procedure is the same on anything. Make sure your on the compression stroke then rotate to line up the damper mark to 0.
Click to expand...
Not correct. How do you know the timing marks on the damper, and timing tab are correct. Over the years the slant six had at least three different dampers and tabs. They will all interchange on the engine, but may or may not be compatible with each other and align at TDC. This must be verified.
 
Ok so i one tooth off on the gear, but I'm not getting spark... New coil but the coil is not sending power to distributor is that the ecu? Cause everything been replaced but that and the distributor I rebuilt but on the shaft in the center a plastic bushing broke so now the distributor moves up and down now?
 
And Charlie I think your right cause I lined it to zero on damper and the Piston still wasn't all the way up. It was on the compression stroke and still didn't line up.
 
MotorHoggGears said:
And Charlie I think your right cause I lined it to zero on damper and the Piston still wasn't all the way up. It was on the compression stroke and still didn't line up.
Click to expand...
And I refer back to My post, the very first response......did You click on that link and read the thread completely? You're pissing in the wind if You don't verify the timing marks align at -0- with cyl. #1 at TDC, which has to be marked as described in that thread.............You must use a piston stop, and mark the balancer for true TDC, if the marks ain't right....or anywhere close, You've got mis-matched/marked components.....................
 
Yeah what Killer said.
I made a piston stop out of an old spark plug. My stamped mark on the pulley was off by only 1/32" but I restamped it anyway.
My 100% rebuilt 225 started right up like it was 1964.
 
Then I would guess You have a slipped damper or the damper/cover are a mismatch. For the time being, use the piston stop method and make You're own new mark on the damper, get 'er running, then get whatever components You need.
 
Do this and youll get #1 TDC no matter what you got going on down there hardware wise: remove all spark plugs.
take a drumstick or pushrod, stick it in #1 sparkplug hole until it hits something and wedges in there, now hold it. turn the crank clockwise with a wrench slowly, if the drumstick moves up, keep turning until it wedges solid on an upstroke (may have to wiggle it to get it to wedge) MARK THE DAMPER @ TDC. Now KEEP THE DRUMSTICK IN ITS WEDGED POSITION and turn the crank backwards 3xx degrees until it wedges again on same drumstick, MARK THE DAMPER @ TDC. Now make a mark exactly between these 2 marks on your damper, that is your damper TDC mark...remove drumstick and rotate to align center mark with timing tab TDC. Your there. Find your compression stroke and you got ignition #1 TDC. Piston stop does same thing but is threaded in and you dont have to hold it.....and is kinda hard to find to fit a slant as it needs a long reach.
piston2.jpg
 
pishta said:
Do this and youll get #1 TDC no matter what you got going on down there hardware wise: remove all spark plugs.
take a drumstick or pushrod, stick it in #1 sparkplug hole until it hits something and wedges in there, now hold it. turn the crank clockwise with a wrench slowly, if the drumstick moves up, keep turning until it wedges solid on an upstroke (may have to wiggle it to get it to wedge) MARK THE DAMPER @ TDC. Now KEEP THE DRUMSTICK IN ITS WEDGED POSITION and turn the crank backwards 3xx degrees until it wedges again on same drumstick, MARK THE DAMPER @ TDC. Now make a mark exactly between these 2 marks on your damper, that is your damper TDC mark...remove drumstick and rotate to align center mark with timing tab TDC. Your there. Find your compression stroke and you got ignition #1 TDC. Piston stop does same thing but is threaded in and you dont have to hold it.....and is kinda hard to find to fit a slant as it needs a long reach.
View attachment 1715369783
Click to expand...
Well, We linked Him to a thread where that was explained but.......................
 
Killer6 said:
Well, We linked Him to a thread where that was explained but.......................
Click to expand...
Oh..this?
"...Get an old spark plug, snap off the ground electrode,then
bust off and out the ceramic and pos. electrode.Once you've hollowed out the plug
body, get yourself a 5/16 all-thread piece about 3.5" long and two nuts, one plain
and one flanged. Put the flanged one on the "top" side,and the plain one chamber
side,run the all-thread thru' almost all out the chamber side. The trickiest part is to
grind the chamber side nut 'till it passes thru' the plug threads,it will be round when
you're done. If you can find a short threaded sleeve that already fits you can skip
that step.
Once you have assembled your positive stop, round the end of the all thread off
w/a file or your grinder so you don't nick or gouge your piston. Then set the
timing marks well before TDC. Install your stop,and with all the plugs out,slowly
bring the crank around by hand 'till it hits the stop.Mark your damper,then roll the
engine back round backwards 'till you hit it again, then make the second mark.
Exactly halfway between those marks is true TDC,at least on that cyl.(#1).."

So good, I had to link it again.....:)
 
You must log in or register to reply here.
-

Back
Top