1968 340 timing

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1968340S

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Trying to set timing....the #1 spark plug wire on the cap is at 3 o'clock and I think its should be at 6 o'clock.
When I use the timing light the reading on the blancher reads.
1
.8
0
right on the 5 degrees mark.
I cant see the one straight line on the balancer at all.
Do I need to move the distributer?
The car runs....not good.
 
Click this link to see factory number one location.
https://www.forbbodiesonly.com/moparforum/attachments/upload_2020-2-18_16-36-51-png.911464/

distributor-install.png


This information is directly from the Factory Service Manual. Any other advice will be based on personal experiences. Not necessarily on your exact application. FWIW.
 
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.the #1 spark plug wire on the cap is at 3 o'clock and I think its should be at 6 o'clock.
Any tower can be #1... #1 is determined by the placement of the rotor..... at #1 TDC-compression; and not anything else.If it runs good then you're all set.
It is customary to have the rotor pointing to the driver's side front intake bolt ..... but not mandatory. It just helps in making custom plugwire kits fit.
If your strobe finds the timing line on the balancer, then you have the right wire; just label your cap accordingly.
Ignition timing for a performance engine is NOT set at idle.
You must defeat the vacuum-advance, then rev it to find the rpm past which the advance has peaked, and make sure your timing there is not more than ~36* . You might have to go to 4000rpm. Then you take her out for a power-test and if it detonates, you have to reduce your power-timing, say 3* and repeat, as often as necessary to get out of detonation.
Then
you check the idle-timing, and modify the parts as may be necessary to get the idle-timing up in the 12 to 16 degree range.
Don't forget to re-install the Vcan, and more testing to find detonation and eliminate it.

You lost me with this
When I use the timing light the reading on the blancher reads.
1
.8
0
right on the 5 degrees mark.
I cant see the one straight line on the balancer at all
The timing tab is calibrated
10 iiiii 0 iiiii 10
If you cannot find the line on the damper; you either are on the wrong wire, or your timing is waaaaaaaaaaay over advanced. Try retarding it
To check the power-timing, you will need either; a timing tape or a dial-back timing lite.
 
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Stock timing is 0* for a standard trans or 5* BTDC for an auto trans. Both came with a dual point distributor. Check dwell before setting the timing. The oil pump shaft slot should point at the left front intake manifold bolt when the timing mark is at 0*. [see post #2]. The rotor should point straight forward when the engine is at 0* on the compression stroke. They ran really well from the factory.
 
Just to clarify;
Every custom plugwire kit I ever installed , has wires of various lengths in the box. Usually, if the D is installed per the factory way, then the wires all fit.
But if the D is installed in one of the "Seven" other positions, usually, no matter how you route the wires, #2 is gonna be too short.lol.
Even after you get the D in as recommended by the factory, It is still possible for the D to be out one tower, and the Vcan kissing the coil, or in some way too close to the radiator, making it impossible to set the power-timing. The Vcan needs to be backed up all the way to the firewall, then pulled forward slightly, until a reluctor-vane aligns with the pole-piece on the Pick-up. or the points just open. I do this with the crank positioned to 10* advanced. This makes an easy-start and fast enough idle, to get started.
After this I slam the rotor on and with a Sharpie,index the housing as to where the rotor is pointing. Then install the cap, and whatever tower is above the index mark I made, is the new #1 plugwire. The rest follow according to the firing order.
If the index mark falls between towers, yur in trouble, something is wrong.
Don't do what I did my first time. I pulled the D and moved the Intermediate shaft one tooth and slammed it all back together, with same results as before, just the rotor moved over to between two different towers. Crap said I; I musta made a mistake. So I did it again with same results. Crap said I; I musta made a mistake. Yes Olie, I moved the I-shaft a third time, with predictable results.
The point is this; the I-shaft has nothing to do with the rotor landing between towers.
If this happens to you;
and you have a Mopar Electronic Ignition system, then;
the reluctor is probable indexed wrong on the roll-pin,and will have to be re-indexed. If you look closely on the reluctor you will see two positions available, with arrows stamped as to their installed direction of rotation. These are supposed to make your rotor line up correctly. If yours still does not line up, then something else has to be moved; either the rotor or the cap.
But if you still have points, then you will have to check that your point gap is correct, and after that your correction points are again; moving the rotor or the cap. or the cam,lol
 
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Unless you have to pass emissions, throw the factory settings in the trash and find what the engine wants for ignition timing. Never had any mopar ever want less than 10* initial/idle timing. You will have to adjust the mechanical advance in the distributor to avoid getting out of bounds on total WOT timing.

The engine doesn't care which tower is number 1 as long as it's phased correctly. If you want the rotor pointing by the book, you may need to adjust the distributor/oil pump drive gear for that alignment. Not all distributors have the keyway and rotor aligned the same.

#1 is drivers side, US cars, front cylinder...
 
To expand on this you can...........

1...Throw the distributor drive gear in blindly not caring where it points

2...Throw the distributor in equally blindly, it will go in 1 of 2 ways, "you don't care."

3...Now bring no1 up on compression, easiest way is stick your finger in no1 hole and crank / bump engine, feel for compression.

4...Bring marks on up NOT to TDC but WHERE YOU WANT timing to be. Look where rotor is pointing "coming to" a tower going CW. This is no1 wire

Retard dist (CW) and slowly bring it advanced (CCW) until points open, or until reluctor/ pickup are aligned.

Plug no1 into that tower, go around CW with the rest, and START THE ENGINE.

Crackedback ^^ above knows his stuff. He has pointed out previously you can SET THE TIMING with a light ON THE STARTER

This entire procedure used to take me maybe 5 minutes.
 
Another potential fly in the ointment.

A late balancer/early timing mark and vice-versa

I FULLY agree with putting your finger over spark plug hole and bump until you find the compression stroke. Look for the timing mark on your balancer wherever it may be as you begin to feel pressure. Timing tab on drivers side of timing cover, should be in the 10-1 o'clock area looking at front of engine. Over pass fender if timing tab on cover are pass side, then 5-7 o'clock.

If you have a mismatched cover/balancer... that's gonna make things difficult and you need to remark the balancer to time your engine properly.
 
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Any tower can be #1... #1 is determined by the placement of the rotor..... at #1 TDC-compression; and not anything else.If it runs good then you're all set.
It is customary to have the rotor pointing to the driver's side front intake bolt ..... but not mandatory. It just helps in making custom plugwire kits fit.
If your strobe finds the timing line on the balancer, then you have the right wire; just label your cap accordingly.
Ignition timing for a performance engine is NOT set at idle.
You must defeat the vacuum-advance, then rev it to find the rpm past which the advance has peaked, and make sure your timing there is not more than ~36* . You might have to go to 4000rpm. Then you take her out for a power-test and if it detonates, you have to reduce your power-timing, say 3* and repeat, as often as necessary to get out of detonation.
Then
you check the idle-timing, and modify the parts as may be necessary to get the idle-timing up in the 12 to 16 degree range.
Don't forget to re-install the Vcan, and more testing to find detonation and eliminate it.

You lost me with this

The timing tab is calibrated
10 iiiii 0 iiiii 10
If you cannot find the line on the damper; you either are on the wrong wire, or your timing is waaaaaaaaaaay over advanced. Try retarding it
To check the power-timing, you will need either; a timing tape or a dial-back timing lite.



Your input has helped me. This is a warranty 340 block...no casting numbers on the front of the block.
The casting numbers 2780930 are located on the block driver side. If I remember there were casting dates 69/70 on the block. The engine has the MSD ignition and the timing tab is on the passenger side of the engine.

I was only checking the timing at idle with the vacuum line removed. Sent a picture of the marks with the timing light at idle. Shut off the engine...just by chance theses marks line up as seen in the picture...the same as the strobe light. The scribe mark on the balancer is at 6 o'clock now....which is approx...6 inches away.

Does this mean that I'm 180 degrees off?

20200517_110630.jpg
 
are you hooked up to the wire for signal to your light on the front passenger side spark plug wire?
 
^^X2^^

I'm not familiar with those marks someone added them? OEM timing mark should be one big deep slot clear across the balancer

Timing light should be on front driver side

Timing marks/ balancer/ tab is different from earlier (pass) to later (driver) side timing tabs. you cannot mix those balancers

Lacking anything else, take a vacuum gauge on manifold vacuum and time it for highest idle speed, then hook up light and "work backwards"
 
Also keep in mind that some timing lights will not give accurate timing results if a MSD is installed.
 
are you hooked up to the wire for signal to your light on the front passenger side spark plug wire?

No.... driver side first plug.... 1357. Passenger side 2468. The distributor can only slide in one or two ways correct? Not like a Chevy having to line up the splines.
 
I'm not familiar with those marks someone added them? OEM timing mark should be one big deep slot clear across the balancer
Same here not familiar, and means nothing to me.

Yur gonna have to get dirty and find TDC #1cylinder, on compression stroke, and find out exactly where your balancer mark is. You may have to make a new one or install a timing tape.

I agree about most timing lights not working with an MSD while it is Multi-Striking below ~3000 rpm. To check the power-timing,you're gonna have to rev it higher.
 
^^X2^^

I'm not familiar with those marks someone added them? OEM timing mark should be one big deep slot clear across the balancer

Timing light should be on front driver side

Timing marks/ balancer/ tab is different from earlier (pass) to later (driver) side timing tabs. you cannot mix those balancers

Lacking anything else, take a vacuum gauge on manifold vacuum and time it for highest idle speed, then hook up light and "work backwards"

Not sure on the balancer. Purchased the car with this set up. I do understand that timing tabs did switch
over from pass to driver (1969/70 maybe). The way my water pump/power steering are located driver side. No way a timing tab would work on the driver side.
 
No.... driver side first plug.... 1357. Passenger side 2468. The distributor can only slide in one or two ways correct? Not like a Chevy having to line up the splines.
Correct,
but neither is correct; there is no correct; as to how it slides in, and there is no wrong. Unless you want to be factory anal about it, and if your D is not a Mopar, It still might not be factory correct.
When the rotor and the tower and the plugwire to #1 plug ,are all three aligned, when the MSD sends the spark, then it is correct .
If it runs at all, then it is correct.
Whether the ignition timing is or is not correct, remains to be seen.
 
Same here not familiar, and means nothing to me.

Yur gonna have to get dirty and find TDC #1cylinder, on compression stroke, and find out exactly where your balancer mark is. You may have to make a new one or install a timing tape.

I agree about most timing lights not working with an MSD while it is Multi-Striking below ~3000 rpm. To check the power-timing,you're gonna have to rev it higher.

I think your right. Its been a while ( 6 years or so ) but I did notice some black marks on the balancer...I think I put there finding TDC. What is timing tape.
 
What is timing tape.
This is a 360* graduated strip of plastic you install onto your balancer, that helps you ;
set your valves,
find TDC of any cylinder
and set your ignition timing.
You have to align the starting point to true TDC, and make sure it goes on in the correct orientation.
You can get one at any performance shop.

With this mounted correctly and a good-quality NON-dial-back timing lite, you should be able to find your mark, or at least get real close to it...... if you are on the right wire.

By the way; 69 and older 340s have a different timing cover and matching damper, than the 70 and ups. The older ones were timed from the passenger side and the newer ones from the driver side. Or was it the other way. In any case to use the timing tabs, you have to have the matching damper, else you cannot find the damper-mark.
This has already been mentioned; go back to post #12.
But if you correctly install the timing tape, then it no longer matters.
 
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And if the wires to signal the MSD are reversed, it can throw the signal off a BUNCH!
 
Correct,
but neither is correct; there is no correct; as to how it slides in, and there is no wrong. Unless you want to be factory anal about it, and if your D is not a Mopar, It still might not be factory correct.
When the rotor and the tower and the plugwire to #1 plug ,are all three aligned, when the MSD sends the spark, then it is correct .
If it runs at all, then it is correct.
Whether the ignition timing is or is not correct, remains to be seen.

Correct. The way I installed the distributor is the only way it will work tower 5 o clock. The vacuum connect to the distributor is so close to the fire wall....it can't be set at 6 o clock....it will hit the fire wall. I'm pretty sure it set it right years ago. This weekend I'll double check everything....TDC....use some timing tape. I'm also checking out all wires...as I did not install this system. The MSD is under the dash.

My son has been using the car. Now when I turn of the running engine at idle 800rmp the tac will stick at that rmp. So I shut the engine off at 1000 rpm and the same...the tac stays 1000rpm. Once the engine has stopped...I can turn the key on just to get power to clear the tac to zero out and the turn the key back all the way off position. As soon as the key is all the way back position. Suddenly I can feel the engine make a slight rotation movement. Like the engine never rested until the tac zero out....does this make any since.
Never had any problems before... until my 25 year son used the car.

Thanks all for your advice. Chris
 
What you posted above is not a problem at all. Many ignitions generate a spark on power up. So if a piston is in just the right position, and a cylinder is charged, it COULD actually start. Also, many newer tachs 'stick' at whatever RPM they were showing at the instant power is cut. Autometer does this

So far as the advance banging on the firewall, I suggest you re-read this thread. All you need to do is rotate the dist body to a more comfortable position, set up the timing marks, and rotate the plug wires appropriately.

It may be the dist. drive gear is not quite correct, or that you have one of the "oddball" distributors with the drive tang "different." There's no need to fight with it.
 
What you posted above is not a problem at all. Many ignitions generate a spark on power up. So if a piston is in just the right position, and a cylinder is charged, it COULD actually start. Also, many newer tachs 'stick' at whatever RPM they were showing at the instant power is cut. Autometer does this

So far as the advance banging on the firewall, I suggest you re-read this thread. All you need to do is rotate the dist body to a more comfortable position, set up the timing marks, and rotate the plug wires appropriately.

It may be the dist. drive gear is not quite correct, or that you have one of the "oddball" distributors with the drive tang "different." There's no need to fight with it.
Thanks for your information.
 
I am setting my 340 up,I have bnoticed that it doesnt "like" the 5 BTDC initial setting, at frist I thought my damper had slipped,but i verified TDC and the mark lines up. My engine seems to like 10 or 15 btdc. It has been converted to MOPAR electronic igintion with Orange box. It will run at 5 btdc,eith 16 inches of mercury on a vac guage, but it doesnt start smoothly,it long cranks. I am thinking it needs more advance.
 
In general, today’s gasoline burns slower than the good old stuff. As a result, the old engines like more initial advance. I’ve found that 10-12 initial works Quite well in most Mopars. However, this usually requires recurving the distributor to ensure total mech advance does not exceed approx 34-36 deg.
Jim
 
It will run at 5 btdc,eith 16 inches of mercury on a vac guage, but it doesnt start smoothly,it long cranks. I am thinking it needs more advance.

While I agree @RealWing, that 10 to12, or even up to 16 works better, I have found that long crank times are more often than not, related to fueling.
IMO, get your fuel-level stabilized, and your transfer slot exposure set right, and things will work better on the hot re-starts
For cold starts, the bowl has to be full, and your choke needs to be working, otherwise you will have to fill the plenum with pumpshot.
If your pumpgas is a week old,and your daytime temps have been over 85*F in the shade, then most of the easier to light components of the gas have evaporated out of your carb, leaving behind the heavy hard to light ones, that are also slower to burn. Earlier timing can help with that. But the cure is to not let the light molecules evaporate in the first place.
Which is a harder thing to do then it might sound like. The lightest molecules are already boiling at 95*F, never mind just evaporating.The heaviest ones might not boil until 400/450. And in between are about 17 other molecules, each with it's own boiling points.
The usual solution is to use a fuel stabilizer, which somehow binds the molecules together, to slow evaporation. It works for me, and my car is stored outside all year.

What you need to know, is that with a cold engine, the A/F ratio needs to be far far richer than what the carb with no choke can deliver. Even with a choke, a lot of the fuel is gonna either lay on the bottom of the plenum,or stick to the cold surfaces.So only a fraction of what you inject, is actually gonna stay airborn, to enter the chamber. And it will be real tricky to light it if it is fresh, never mind if it is stale.
The proof of this is when you say;
"it doesnt start smoothly"
The rest of that fuel, that is just laying in on the floor, after the engine starts, immediately starts dumping into the chamber, and the A/F ratio is again all wrong, and a lot of that is gonna pass straight thru unburned; partly because the fire started too late,and partly because the heat of compression was not sufficient to light that heavychit up, and partly because the droplets are too big to light up.

As to timing;
Your engine will like a lot of it at idle. All you gotta do to see it, is just tug on the Vcan until the rpm stops rising. When it stops, the pressure to the crank is maximized and more timing will not be better. Now put your timing lite on it and see what you get. I'll guess more than 20, less than 30 at 750rpm. This is the optimum timing for that rpm.
Of course , few engines will accept that, because it is as good as impossible to build a power-timing curve with that number whatever it is. And power-timing always trumps all other timings,else the engine is likely to break due to detonation.
Ok so,unless you have a timing computer, your cranking timing is the same as your idle timing, and can be anywhere in that range of 5 to say 25 degrees, until your starter can no longer fight the compression that is being generated by such early sparking. Typically we see about 20 as the max .
But then you run into these other walls;
1) as @RealWing mentions, you gotta limit your power timing to what your particular engine wants, so now, you have to recurve that distributor. This HAS to be done every time you select a different idle-timing, unless, during testing, you promise to stay out of WOT.and
TWO) every time you change the idle timing, you will have to reset the idle speed. And when you do, you upset the relationship of the transfer slots to the mixture screws. And that is almost guaranteed to cause tip-in sags, hesitations of even mild bogs. and
3) If you have a V-can; every time you recurve your distributor, the cruise timing and the Part-Throttle timing will change; usually for the better, but not always.

Finally, even if your engine is stock, the factory idle-timing was selected not to favor the engine, but to favor emission controls. So it was never right in the first place. We got away with that in the 60s and early 70s, because we had infinitely better gas. Those earlier engines do not much like today's gas.
As Realwing says;
n general, today’s gasoline burns slower than the good old stuff. As a result, the old engines like more initial advance
You cannot hurt your engine by cranking in more idle timing, unless you forget
However, this usually requires recurving the distributor to ensure total mech advance does not exceed approx 34-36 deg.
Jim
and finally
Just remember about item TWO above.
 
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