Can't get timing dialed back to tdc

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Al Bundy

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I am trying to adjust the timing on my 70 dart (slant six) it is showing it running about 6-7 degrees after top dead center at idle with advance line disconnected. I loosened the bolt on the distributor to turn in back to top dead center or a little before and it can't turn back any further,I can only advance it more. Could someone have installed the plug wires on the cap to far forward in the holes? if someone pulled the distributor before I bought the car to do the points is it possible they installed it slight off? I know it's usually dead on or completely opposite on most cars,but these have a gear instead of a slot that drives them.
I'm thinking maybe the fact it's running 6-7 degrees after top dead center (right side of tdc on scale with me facing engine) might have something to do with the fact it starts hard after sitting ten minutes or so after running,but fires at the bump of the key when it cools.

Any help surely would be appreciated.
 
I think the mount has two slots and bolts, one on block, the other on bottom of distributor. The one on the bottom is out of sight. The other option is pull distributor and change the drive gear index by a tooth.

You might want to check if TDC is correct at balancer.
 
KitCarlson said:
I think the mount has two slots and bolts, one on block, the other on bottom of distributor. The one on the bottom is out of sight. The other option is pull distributor and change the drive gear index by a tooth.
Click to expand...

What would have caused this? Someone pulling the distributor and then not aligning it correctly? About how far is "a tooth"? I looked online and the gear drive is spiraled.
 
I also checked the vacuum advance diaphragm by pulled the carb end of the vacuum hose and sucking on it and it's leaving like a sieve. Absolutely no suction at all,and yes,I did check the hose for leaks and its holding vacuum fine. After I get the timing issue settled I have to deal with that. Is it easy to replace just the diaphragm?

Funny thing,wouldn't the engine idle rough or stall if the diaphragm is leaking this bad? It idles fine and seems to run fine on the freeway.
 
To replace the dashpot, best to have distributor out, two screws and fit end into advance plate. It has been 35+ years since I have done that, not sure.

If you count the teeth, the total is 720 degrees at crank. Just checked, 13 teeth, so about 55 degrees, that is a bit much.

Working on a \6 distributor out is best for setting points and other adjustments. Before pulling index engine note rotor position, mark distributor.... But is your case since it is off, start from scratch follow manual and make it correct.

Slant6 org has info here: https://www.google.com/search?q=slant+6+distributor+hold+down&espv=2&biw=1242&bih=585&tbm=isch&imgil=6VLykhHxZNhv6M%253A%253BNFGkL4FV2t3K9M%253Bhttp%25253A%25252F%25252Fwww.slantsix.org%25252Fforum%25252Fviewtopic.php%25253Fp%2525253D313168%25252526sid%2525253D7bb6b9d4f47cc326c3cd2e2c6e5388da&source=iu&pf=m&fir=6VLykhHxZNhv6M%253A%252CNFGkL4FV2t3K9M%252C_&usg=__g4YrZWaSJUl72N0gyFf8rqMV1rE%3D&ved=0ahUKEwjzq6aLm8PKAhUBbj4KHVv_DkgQyjcIJw&ei=0imlVvP6I4Hc-QHb_rvABA#imgrc=6VLykhHxZNhv6M%3A
 
KitCarlson said:
You might want to check if TDC is correct at balancer.
Click to expand...


I can see only one notch in the harmonic balancer,when I put my timing light on it it's there at 6-7 degrees after top dead center and the distributor is turn as far counter clockwise as possible. It was set that way when I got it. Rotating it clockwise advances it and makes the issue worse.
 
KitCarlson said:
To replace the dashpot, best to have distributor out, two screws and fit end into advance plate. It has been 35+ years since I have done that, not sure.

If you count the teeth, the total is 720 degrees at crank. Just checked, 13 teeth, so about 55 degrees, that is a bit much.

Slant6 org has info here: https://www.google.com/search?q=slant+6+distributor+hold+down&espv=2&biw=1242&bih=585&tbm=isch&imgil=6VLykhHxZNhv6M%253A%253BNFGkL4FV2t3K9M%253Bhttp%25253A%25252F%25252Fwww.slantsix.org%25252Fforum%25252Fviewtopic.php%25253Fp%2525253D313168%25252526sid%2525253D7bb6b9d4f47cc326c3cd2e2c6e5388da&source=iu&pf=m&fir=6VLykhHxZNhv6M%253A%252CNFGkL4FV2t3K9M%252C_&usg=__g4YrZWaSJUl72N0gyFf8rqMV1rE%3D&ved=0ahUKEwjzq6aLm8PKAhUBbj4KHVv_DkgQyjcIJw&ei=0imlVvP6I4Hc-QHb_rvABA#imgrc=6VLykhHxZNhv6M%3A
Click to expand...


I looked at the photo in your link and see what you mean about the bolt underneath,you have to pull the distributor to do that too. If I have to pull the distributor I guess i should try moving the roto counter clockwise a tooth.
 
I seem to remember that it is possible to adjust the bottom bolt, if you are good with working with tools by feel.

I was suggesting that you check that the TDC is when piston is at top. There are piston stops to check that. Google that.
 
you either have to pull the distributor and move it one gear tooth if it's "really" too far

Or move the plug wires which is not 'by the book'

And yes, for smaller movements, loosen the bolt going "up into" the distributor and move the clamp device

Some had a clamp like this

slant-elec-ign-1.jpg


Others had a second slot and bolt up into the dist. body

dist-wrench.jpg


Don' you have a factory manual? Wander over to MyMopar and download one, free
 
KitCarlson said:
I seem to remember that it is possible to adjust the bottom bolt, if you are good with working with tools by feel.

I was suggesting that you check that the TDC is when piston is at top. There are piston stops to check that. Google that.
Click to expand...

Yes,I did that. When the timing mark is at tdc on the balancer the rotor on the distributor is at the number one position.
 
67Dart273 said:
you either have to pull the distributor and move it one gear tooth if it's "really" too far

Or move the plug wires which is not 'by the book'

And yes, for smaller movements, loosen the bolt going "up into" the distributor and move the clamp device

Some had a clamp like this

slant-elec-ign-1.jpg


Others had a second slot and bolt up into the dist. body

dist-wrench.jpg


Don' you have a factory manual? Wander over to MyMopar and download one, free
Click to expand...

Thanks for the pictures. I don't have an actually vintage factory service manual for this car,it's the only mopar I own that I don't have one for. For some reason everytime I've looked online people have been asking insane prices for greasy beat up ones. I actually got most of my other older mopar manuals for between $19-25 each so it seems funny that the newer (late 60's,early 70's) manuals seem to be higher priced. Must have something to do with demand.
I do know about the free ones you can download on the Internet,but I had to bring a laptop into the garage.
I figured it was alright to ask questions here and get other people's advice on things as there are often different approaches to doing something,as I've learned here. I can either pull the distributor,loosen the bolt on the bottom or move the plug wires ahead one spot. Besides the forum would be a ghost town of nobody asked questions or discussed things here. If this was already discussed here I apologize for bringing it up again.

Sure wish I had that neat tool to get at the bolt. :glasses7:
 
Al Bundy said:
I figured it was alright to ask questions here and get other people's advice on things as there are often different approaches to doing something,as I've learned here. I can either pull the distributor,loosen the bolt on the bottom or move the plug wires ahead one spot. Besides the forum would be a ghost town of nobody asked questions or discussed things here. If this was already discussed here I apologize for bringing it up again.
Click to expand...

You're fine asking questions, what Del is relaying to you is each of us really should have an FSM for our cars. I didn't for a while, and there isn't much I can't do or figure out on it. I finally bought one a couple of years ago just to have it.
 
I really don't think timing is causing the hard start when hot issue. Most of us have to run more advance than the original tune up spec due to todays fuels. Good luck with it.
 
RedFish said:
I really don't think timing is causing the hard start when hot issue. Most of us have to run more advance than the original tune up spec due to todays fuels. Good luck with it.
Click to expand...

Yes,I am thinking that's a likely a fuel or carb related issue as well. But I know timing being too far advanced or retarded can also make starting more difficult. I've heard people comment that today's ethanol laced fuels percolate off after the engine shuts off.

Right now my timing isn't advanced,it's retarded. The factory specs say top dead center at 650 rpm idle,a member here recommened I try 5 degrees before top dead center,right now,according to the timing mark it's running at 6-7 degrees AFTER top dead center. I'm sure it will run much better once I get the timing set correctly. Would you recommend 5 degrees before tdc too?
 
Is it possible the cam drive has slipped? I don't remember how much that changes timing.

Also some? slants have plastic drive gears
 
Points ?
The Point-gap changes the timing. If the gap is very tight, the timing will go late.My old slantys used to run fine at several thou over factory.

On my 1980 Volare I had to lengthen the slot to get some decent advance(EI).

As someone else mentioned find true TDC and compare to your mark
 
67Dart273 said:
Is it possible the cam drive has slipped? I don't remember how much that changes timing.

Also some? slants have plastic drive gears
Click to expand...

The car has been this way since I bought it. It runs fine.it doesn't hesitate,ping,etc. I checked the points and they are gapped correctly. The distributor was adjusted all the way counterclockwise as far as it can go by the pervious owner. I put my timing light to see where it was at because it bothered me that the distributor was adjusted to the limit counterclockwise and I know the timing changes as the points wear so I figured I'd time it. I am guessing the previous owner pulled the distributor to replace the points and condensor installed it slightly off. The number one spark plug wire is in the cap socket nearest to the vacuum advance pot as it should be according to what I've read here.
Since the diaphragm holds no vacuum and I ordered a replacement that is supposed to be in tomorrow I will pull the distributor then and check the gear at that time. How many degrees will putting the rotor back one tooth put me?

Why would the cam drive slip?
 
AJ/FormS said:
Points ?
The Point-gap changes the timing. If the gap is very tight, the timing will go late.My old slantys used to run fine at several thou over factory.

On my 1980 Volare I had to lengthen the slot to get some decent advance(EI).

As someone else mentioned find true TDC and compare to your mark
Click to expand...

I checked the points with a feeler gauge and they are gapped to specs. with the distributor turned to its limit counterclockwise the timing mark is at 6-7 degrees after top dead center.
 
Moving the drive gear accomplishes little to nothing,cuz, you just reclock the point cam, the canister moves to a new location, but way too far.I tried this years ago, to no good success. There just was not enough slots to achieve the goal, on my application.
IMO;you really have to prove the TDC mark first, then lengthen the slots as may be required.
 
AJ/FormS said:
Moving the drive gear accomplishes little to nothing,cuz, you just reclock the point cam, the canister moves to a new location, but way too far.I tried this years ago, to no good success. There just was not enough slots to achieve the goal, on my application.
IMO;you really have to prove the TDC mark first, then lengthen the slots as may be required.
Click to expand...

How do I prove the TDC mark? Im curious,why would that change and how likely is that to happen? When I rotate the harmonic balancer timing Mark to line up with tdc the rotor on the distibutor is exactly on the number one position as it should be. Why would tdc drift to the point that you couldn't dial the distributor back to tdc on the timing Mark? I've never seen this happen on any of the cars I've owned and all are much older than 1970. I know timing gears can supposedly jump a tooth,but that isnt that common of an occurance is it? That mostly happens on high mile engines. Our cars don't have nylon timing years like GM's do they? Wouldn't it seem more likely someone pulled out the distibutor and put it back in slightly off since it was like that when I bought it? Sorry for all the questions. Just wondering. I've never had this issue before.
Has your car ever gone this out of time that you couldn't adjust it back? There is only one timing Mark stamped into the balancer right? I didn't see another.
 
Well, consider this ; suppose the timing mark slipped 10 degrees over a few weeks or months, or years,for the previous owner. So it started to run worse and and worse. So the previous owner gives it a tune up, including resetting the timing . So now everything is lined up again, but the timing is all wrong. The rotor lines up,just as it should..
So to your first question, checking the TDC mark. You need a special tool called a piston stop. It screws into the sparkplug hole and when you turn the crank by hand, the piston comes up close to the top and hits it and then stops.Then you turn the engine backwards until it again stops.The exact difference between the stopping points, devided by two, is true TDC. The stop is usually adjustable to fit multiple engines. So what I do,on a slanty is use no 6 hole, so I don't have to mess with the alternator.I take out all the plugs to make hand-turning it easier Than I line up the TDC ballancer mark to the TDC pointer. Then I turn the engine over backwards to 10* advanced. Then I install the tool screwing it in until it hits the piston, and lock it down with the jam-nut. Then I turn the engine a couple of degrees backwards. Then gently slam it into the stop. Mark the ballancer where the TDC index tab says TDC. Then rotate the engine over backwards until the piston again gently slams into the stop, and again mark the TDC point on the balancer. Remove the stop. Crank the engine over a few degrees until both marks you made are clearly visible. TDC will be exactly half way between those two marks. Measure with a flexible tape, and mark it. That is true TDC. And you have proven it.
It may well be that your new mark is exactly where the factory put it.But until you have proven it, tuning a problem like yours is all guesswork.And if it is not within a degree or three, it is junk!
Good luck
 
Thanks Aj/FormS for the detailed instructions. I will have to see if the auto parts store rents one of those piston stops. Has this happened to you before? How common is it for the timing to just drift and what causes that to happen?

Edit-just watched a video on YouTube about the piston stop,the guy said its not very common but apparently a harmonic balanced can shift and the timing marks will be off. Must have something to do with the rubber isolator?
 
Al Bundy said:
I am trying to adjust the timing on my 70 dart (slant six) it is showing it running about 6-7 degrees after top dead center at idle with advance line disconnected. I loosened the bolt on the distributor to turn in back to top dead center or a little before and it can't turn back any further,I can only advance it more. Could someone have installed the plug wires on the cap to far forward in the holes? if someone pulled the distributor before I bought the car to do the points is it possible they installed it slight off? I know it's usually dead on or completely opposite on most cars,but these have a gear instead of a slot that drives them.
I'm thinking maybe the fact it's running 6-7 degrees after top dead center (right side of tdc on scale with me facing engine) might have something to do with the fact it starts hard after sitting ten minutes or so after running,but fires at the bump of the key when it cools.

Any help surely would be appreciated.
Click to expand...

...........Unless I'm totally reading this wrong, to advance u have to move the dist ahead not push it back, which u say the timing advances when u pull it ahead.......when u push the dist back u r retarding the timing which will be after tdc.....it will start harder with the timing retarded.......too much timing can cause a hard start by making the engine crank slower or maybe not at all when warmed up...........kim.......post a couple of pics to help clarify ur delima
 
Al Bundy said:
Must have something to do with the rubber isolator?
Click to expand...

It "exactly" has something to do with. In my Navy days, part time job at the base hobby shop I found a number of Fords (352/ 390) that were off for some reason
 
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