Timing rod length with a 7 degree advanced timing gear

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Model T Ford Forum: Forum 2015: Timing rod length with a 7 degree advanced timing gear
Top of pagePrevious messageNext messageBottom of page Link to this message  By lee crenshaw on Wednesday, May 27, 2015 - 11:10 pm:

I'm working on a '13 touring which is equipped with a 7 degree advanced timing gear.
With the timing set by piston travel and using
a new TW timer; I am getting a kick-back on cranking. Do I need to extend the timing rod to retard the spark?
Lee


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Wednesday, May 27, 2015 - 11:22 pm:

No you need to re time it. The advanced gear does not change where top dead center is for the pistons. The pin on the crank pulley still needs to be just past horizontal and the piston just going into the down stroke. If you have set the timer to just start buzzing and bent the rod to connect it with the spark lever in the up position you should be good to go. Make sure you are setting it to fire on No 1 compression stroke.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Wednesday, May 27, 2015 - 11:25 pm:

I have that gear on mine and in my case did not change the rod that connects all that much. I am running a New Day.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John F. Regan on Thursday, May 28, 2015 - 12:03 am:

As Mark said the timing needs to be set based upon the piston position which will be exactly at top dead center for any one piston when the front crank shaft pulley pin is exactly horizontal.

I first advance the timing lever on the column and then slowly pull it back to the full up (full retard) position. Moving the lever like that is important because it leaves all of the slack in the timer linkage in the correct place. Failure to do that when you have slack in your linkage can result in kick back because the linkage can then later leave the timer more advanced than when you set up the timing because there is always "some" slack in the timing linkage. Once I have the lever in that position I just turn the ignition on to BAT and pull the hand crank very very slowly until I hear a coil buzz. I instantly stop and pull the hand crank back out of the front of the motor and peer into the pulley and look at the pin. It should be a wee bit past horizontal position so like hands on the clock it should have the right side pin position being just past 3 o'clock. I disagree that it matters at all which cylinder is coming up since every half turn of the motor results in the pin again being horizontal and another cylinder firing. All of them should fire at about 7-15 degrees AFTER top dead center which is where you will be if you have the pin slightly lower on the right (just past the 3 o'clock position). The pin in the front of the crank is drilled at angle 0.000 degrees (TDC) and is the reference for all of the throws of the crankshaft when they were ground so using that reference is the most accurate way to set up the ignition timing. This method is the same for any timer and allows you to look at the timing for each cylinder in turn as you rotate the engine a half turn at a time since you will then measure the timing of all 4 cylinders which should be at the same pin position.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Thursday, May 28, 2015 - 06:45 pm:

Lee: Take Mark's advice, the 7 degrees advance is on the valve timing, not the ignition timing. Check your ignition timing to correct the "kick" you observed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom 30 miles N of Memphis TN on Thursday, May 28, 2015 - 07:21 pm:

Just to be clear, a advanced cam gear will in fact cause the ignition timing to be advanced as well. The roller will now move in the advanced position and the rod needs to be adjusted per the advice John gave to move the case back so it occurs past TDC slightly.

If no other changes are made other than the gear the new timing on battery will happen sooner than before. It has to happen as the roller is bolted to the cam that you advanced.


Top of pagePrevious messageNext messageBottom of page Link to this message  By lee crenshaw on Friday, May 29, 2015 - 01:54 pm:

Thanks to all respondees. Gary, what you outline confirms my experimentation.
Lee


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Friday, May 29, 2015 - 09:09 pm:

Has common sense gone south ???? Crank position ( ie. piston position) determines initial spark setting.

The advance in valve timing that the modified cam gear does just that..... advances the valve timing !

Time your engine according to the brand of timer you are using.

I have the same 7 degree advanced cam gear, used with a Anderson Timer, NOS Anderson Timer, and the E-Timer..... all had them spark rod length adjusted according to piston position in initial timing setting.

Bob Jablonski


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom 30 miles N of Memphis TN on Friday, May 29, 2015 - 09:33 pm:

Crank position determines actual timing when running on mag. The initial question indicated that after installing the advanced gear, the engine was kicking back (indicative of starting on battery). There is no way to advance the cam without advancing the rotor indexed and fastened to the end of said cam. The rotor making contact determines timing on battery. Cam/roller advances = timing occurs 7 1/2 degrees sooner if the rod isn't adjusted to set it back where it was initially. To correct the timing back to its initial point the rod has to be adjusted thereby moving the timer case.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Friday, May 29, 2015 - 09:36 pm:

I state again, common sense had gone south.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom 30 miles N of Memphis TN on Friday, May 29, 2015 - 09:57 pm:

Let me explain this "common" for you Bob. Imagine for a moment that the original poster didn't install the gear in question. When he attempted to start the car he advanced the spark lever and the car kicked. Why?

Now, leave the spark lever alone but go inside the case and move the roller towards some advanced setting. The engine will kick back on start attempt. Why?

Now, let's say he installed an advance gear which moved the cam 3 3/4 degrees (cause that is exactly what happened). The roller had no choice but to move by the exact same amount as the cam. Just like scenario #2, the engine will kick back on start attempt.

Now, unless he adjust the position of the case the roller will still make contact sooner than it did before.

Next time you decide to take a swipe at someone's common sense, make sure you understand what you're talking about.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Friday, May 29, 2015 - 10:57 pm:

Gary: What about piston position on setting initial ignition spark setting ? That's the basis of any brand of timer initial setting..... they're all a bit different. Agreed ?????

Valve timing advance offered by the 7.5 degree cam gear changes the opening & closing of the valves, not the ignition timing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie Spokane, WA on Saturday, May 30, 2015 - 12:18 am:

Bob, it changes the ignition timing too because the rotor or brush or roller is hooked onto the camshaft. It is advances relative to the crank (and hence the pistons).


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Saturday, May 30, 2015 - 07:35 am:

Thanks Tom, any advice to help Lee properly set his initial commutator setting ?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Saturday, May 30, 2015 - 07:39 am:

I agree with Mark G. with initial setting with any commutator brand.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom 30 miles N of Memphis TN on Saturday, May 30, 2015 - 08:13 am:

Both Mark and John explained how to set the initial. Position the piston a few degrees past TDC, set the timer case to just start to buzz and bend the rod to fit. Once complete, the car will not kick with the spark lever all the way up.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Jablonski on Saturday, May 30, 2015 - 10:55 am:

Very good Gary !! Now explain how the 7.5 degree valve timing effects the ignition timing as you believe, and how to set ignition timing with the advanced cam gear to prevent kick-back.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Robison on Saturday, May 30, 2015 - 11:16 am:

http://www.spokanemodeltclub.com/how-to-time-a-model-t.php

Follow these direction


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom 30 miles N of Memphis TN on Saturday, May 30, 2015 - 11:44 am:

Having difficulty explaining in terms you will understand but will try again. When one installs the advanced gear the rotor advances as well. There is then a need to adjust the rod length to position the case 3 3/4 degrees in the same direction as the movement of the rotor. If you don't do it then, when starting on battery the spark will occur 7 1/2 degrees sooner than before you advanced the gear. Depending on where it was initially, that may be enough to cause kickback as Lee was getting.

After installing, all a person need do is time the timer as normal. If that is ignored, the risk of kick back is increased.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Cameron Whitaker, Choctaw OK on Saturday, May 30, 2015 - 11:45 am:

Putting in an advanced timing gear will absolutely advance the ignition timing! After all, the timer rotor is in a fixed position relative to the camshaft. Advancing the camshaft (I.e., valve timing) will also advance the ignition by double, since the crankshaft turns twice as fast.

Yes, the ignition timing needs to be done with respect to piston travel. However, since the camshaft is now 7 degrees advanced, the ignition timing will be 14 degrees advanced relative to the crankshaft, since the camshaft turns at half of the crankshaft speed. Thus, the timing will definitely need to be readjusted!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom 30 miles N of Memphis TN on Saturday, May 30, 2015 - 12:21 pm:

The cam gear only moves 3 3/4 degrees with the advanced gear. The valve timing is expressed in crankshaft degrees hence the 7.5. There are 48 teeth on the cam gear and most folks only advance by 1/2 tooth. This gives the 7 1\2 advance as expressed in crankshaft degrees.

You are correct that the rotor affixed to the cam advances by the same amount and unless corrected, will affect ignition initial timing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Saturday, May 30, 2015 - 12:22 pm:

DO NOT USE THE TIMER GAUGE OR FORD NUMBERS TO SET THE TIMER WHEN USING ADVANCED GEAR!

Here is how I time mine;
Take all the spark plugs out and with wires connected lay on engine head. (You don't have to but make it safer and easier to to crank)
Bring No 1 up on compression stroke.
Watching the piston, stop turning when just goes over on down stroke, confirm by looking at crank pin.
Turn key on. If the coil is buzzing with the lever up, turn key back off.
Remove timing rod from timer. Turn key back on.
Turn timer counter clock wise till buzzing stops then clockwise till it just starts.
Bend rod as needed to enter mounting hole on timer and replace cotter pin.

I start on battery and switch to magneto after the car is running and the spark is advanced.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom 30 miles N of Memphis TN on Saturday, May 30, 2015 - 12:23 pm:

Cameron, I like the fender brace in your profile picture.


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