Question re setting timer position at full retard…

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Chris Bamford
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Question re setting timer position at full retard…

Post by Chris Bamford » Thu Jun 01, 2023 11:42 am

I’m checking my TW timer position against the initial spark when on Batt.

A forum search advises first spark should occur 15 deg ATDC, and that TDC occurs when the crank pin position is horizontal. Fair enough.

My challenge is that the crank pin is hidden by the radiator, crank, pulley and fan belt. See photo below. I need an easier way to determine TDC.

My understanding has been that when the hand crank is vertical (or possibly horizontal) that one cylinder will be at TDC. Is this correct, assuming the hand crank is not twisted)?

If so, then my initial timing is way off, as first spark at full retard on Batt occurs when the hand crank is 40 deg ATDC. This is consistent over cylinders 1, 2 and 4. Cylinder 3 is 10 deg sooner; a different issue and I’m pulling the timer to investigate.

In the meantime, where exactly is TDC when the hand crank is vertical?
IMG_3004.jpeg


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Re: Question re setting timer position at full retard…

Post by Been Here Before » Thu Jun 01, 2023 11:48 am

To locate TDC, in relation to the starting crank, in relation to your motor...pull the No. 1 sparking plug and turn motor by hand crank to get TDC - both intake and exhaust closed. Note location of starting handle.


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Re: Question re setting timer position at full retard…

Post by Jerry VanOoteghem » Thu Jun 01, 2023 11:51 am

You have an aluminum crankshaft pulley. They are usually split, with a clamp screw to secure them tightly. That split line runs perpendicular to the crank pin hole. Use that as your reference. At TDC, the split will either be at the 12 or 6 O'clock position, depending on how you mounted it. Determine if it's on the compression stroke by placing your thumb over the #1 plug hole while cranking. When you feel a puff, you're on compression. Then, just get the split line vertical and you're on TDC.

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Re: Question re setting timer position at full retard…

Post by Humblej » Thu Jun 01, 2023 12:11 pm

Remove the #1 spark plug, insert a wire like a coat hanger wire into the spark plug hole and angle it to ride the piston. Watch the wire go up and down as you crank the engine over. You will see TDC easily.

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Re: Question re setting timer position at full retard…

Post by Steve Jelf » Thu Jun 01, 2023 12:50 pm

I assume you're dealing with a 24-27 T with a radiator apron blocking your view of the pin. While crank position may get you close to TDC, most crank ratchets are worn enough to be off a little. I would use Jerry's method to find TDC. Remember that contact is supposed to be at 15º past TDC. Thinking of the pin as a clock hand, that's halfway between 3 and 4.
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Re: Question re setting timer position at full retard…

Post by Art M » Thu Jun 01, 2023 9:30 pm

Going from TDC to 15 degrees past, the crank handle moves approximately 2 inches.

Art Mirtes

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Re: Question re setting timer position at full retard…

Post by Chris Bamford » Thu Jun 01, 2023 11:48 pm

Thanks to all who posted and especially you, Jerry. I will report back in a day or two.


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Re: Question re setting timer position at full retard…

Post by DHort » Fri Jun 02, 2023 1:18 am

An old trick was to use a straw from McDonalds resting on the piston. You can also use a dowel, a metal rod, whatever. Or do it with a friend and have him/her watch the crank pin as you slowly crank it. Lots of good ideas here. Remember, if you go to far, 2 times around and you are back at TDC. If the crank is tight, loosen all 4 plugs and it will be much easier to turn.

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Re: Question re setting timer position at full retard…

Post by TWrenn » Fri Jun 02, 2023 10:00 am

If I'm not mistaken, and sadly I often am...lol...as I recall from my own experience I believe when the crank pin is horizontal, and you "mate up" the crank ratchet into it, your handle arm should be almost the same position, as well as looking down the radiator at the crank ratchet, you should see the pin that holds the ratchet to the arm. Pretty sure anyway. Give it a try and a look-see. And good luck! Best thing is, you're also using what I consider the best timer on earth.

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Re: Question re setting timer position at full retard…

Post by John.Zibell » Fri Jun 02, 2023 12:31 pm

This tool works well to set initial timing. http://www.modeltford.com/item/3021SKLED.aspx
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Re: Question re setting timer position at full retard…

Post by Steve Jelf » Fri Jun 02, 2023 2:56 pm

Does it work $86+ better than a straw? :D
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Re: Question re setting timer position at full retard…

Post by Been Here Before » Fri Jun 02, 2023 4:52 pm

This is a tough crowd....

"Does it work $86+ better than a straw"

Doesn't an etimer make finding TDC easier at $540.00, than finding a straw?? :lol: :lol: :lol:

Setting the Proper timing
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Re: Question re setting timer position at full retard…

Post by Chris Bamford » Fri Jun 02, 2023 5:45 pm

This has been interesting. And very puzzling.

The TW timer appeared to be +/-10° earlier timing on #3, so I replaced it with an unused repro roller timer. I took Jerry's suggestion to align the pulley split straight up vertical to ensure the crank pin is horizontal, thus positioning pistons 1 and 4 at TDC. I bulked up a broken hacksaw blade and jammed it down the split as an indicator, then adjusted the crank position minutely until the blade appeared vertical when aligned with the block casting parting line. RH photo is with the saw blade reversed to confirm position.

26T find TDC.jpg

I then made up a rad-width protractor to mark and measure actual TDC and the first spark on Bat for three timing lever positions: full retard, partial advance, and full advance. There are two TDC positions shown (with the hacksaw blade unchanged). These are one reading with the handle up and one with it down (I expect the variation is socket irregularities). I used the Blue crank position for all readings. All measurements were done twice, although only the Full Retard is shown twice. There was good repeatability throughout. While the absolute readings are of interest, relative positions are probably most important.

- The crank pin is horizontal when this crank handle is 19° before vertical
- Full retard ranges from 21-37° ATDC (16° spread) compared to, if I recall correctly, typically 15° ATDC and minimal spread
- Partial advance varied 8-27° BTDC (19° spread)
- Full advance varied 28-48° BTDC (20° spread)

26T static timing.jpeg
So, here's what I don't understand...
— why does the spread from first plug firing to last plug firing increase by 4° when the spark is advanced?
— Why does the distribution of firing times vary more with advanced start (from 2 pairs at retard to 4 different at advance)
— looking at the commutator wiring diagram, I see no scenario where segments 1 and 4 (opposites) are both late while 2 and 3 (also opposites) are both early. This would indicate the timer is oval shaped, no?
- although the timer cover is a bit sloppy in the front plate, I can't see which direction it should go to correct this imbalance in firing times.

The engine enjoyed a recent professional overhaul and the coils are adjusted for consistent time to fire (+/- a few Ms). I generally run on magneto, but assume if the timing is this uneven on Bat it will be out similarly on Mag. Big tour next week!

What am I missing?


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Re: Question re setting timer position at full retard…

Post by ThreePedalTapDancer » Fri Jun 02, 2023 5:54 pm

Steve Jelf wrote:
Fri Jun 02, 2023 2:56 pm
Does it work $86+ better than a straw? :D

Yes it does, because you don’t have to worry about getting oil in your teeth when you re-use the straw again later.
Last edited by ThreePedalTapDancer on Fri Jun 02, 2023 10:06 pm, edited 1 time in total.


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Re: Question re setting timer position at full retard…

Post by speedytinc » Fri Jun 02, 2023 6:42 pm

Sloppy timer fit & gear cover variation will account for minimal firing variation. Your firing inaccuracy is due to the spacing in the timer bodies contact ingress positions. Try locking the timer down turned 180 degrees. Your new results should prove timer contact error. I would not have expected this kind of variation in a roller timer, but have not tested them myself.

Try a new day timer. They do have varying amounts of error depending on the position of the contacts in the mold. The worst I have seen can vary +- 6 degrees @ the crank.

If you want the most accurate timing, I believe that can be attained with a anderson type flapper timer. Using the same protractor setup, The variation can be removed by tweeking the contacts.

I have been able to get accurate timing from New Day's by re-cutting the ingress points on the contacts to take out the varying manufacturing error.
Of course, timing cover error is eliminated from the timer recess by accurately centering the gear cover.


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Re: Question re setting timer position at full retard…

Post by Scott_Conger » Fri Jun 02, 2023 7:39 pm

Chris

when on battery, the plug fires exactly when the contact is first made on the timer housing and if that housing has any built in errors, then the plug firing (timing) will reflect those errors

when on MAG, the plug can only fire on sine wave output of the coil ring (and a contact is made in the timer concurrently), meaning, just because the roller/flapper has JUST made contact, no plug will fire until (while on some portion of the contact) the magnets pass a pole face on the mag ring. Ron Patterson did a very good paper on this and is worth researching on the forum

Note: if there are errors due to misalignment of the timing cover or a mechanical error (such as bent ANCO tab) then when on battery, no coil tuning whether by amperage or TTF will make the car run its best as you are at the mercy of whenever the timer first makes contact...however when on MAG, because the firing is dead even due to sine wave input from magneto assembly, then a very accurately tuned coil will result in a very accurately firing plug.

This is why when on battery, every tiny bit of timer lever movement results in spark advance, and when on MAG, you can move the timing lever through quite a range of movement (several notches) and nothing changes until a significant movement of the lever occurs...this change being the timer having finally moved enough that the advancement of the timer is sufficient to catch the earlier occurring sine wave crossing, or "node" as described by Patterson.

Don't sweat this thing and enjoy your tour.

Patterson's excellent paper describing how the ignition system works:
ignition2.pdf
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Re: Question re setting timer position at full retard…

Post by Art M » Fri Jun 02, 2023 9:54 pm

I made a tool to check the timer accuracy and initial error The device consists of a used camshaft, a timing gear cover, a camshaft gear, and a fixture to hold things in place. I found a degree or so of error at the timing gear with roller timers. The crankshaft error is twice this. I will post a picture as soon as I learn how to post a picture.

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Re: Question re setting timer position at full retard…

Post by DHort » Fri Jun 02, 2023 11:01 pm

I-timer is only $424, but if you want an E-timer.....

You still have to find TDC after you install any timer of your choice, and adjust it.

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Re: Question re setting timer position at full retard…

Post by JTT3 » Sat Jun 03, 2023 1:36 am

If I’m not mistaken there is a pin that you had to drive through the pulley & crankshaft, by locating that hole where the pin was driven through and marking it on the front of the shoulder of the pulley with and indelible marker you should easily see the position of the pin. You may even mark both sides 180 out on the pin holes location with different colored markers so you can note the position of the piston. Around 3:30 as on a clock is 15 degrees ptdc I believe. Could be wrong though.


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Re: Question re setting timer position at full retard…

Post by Dan Hatch » Sat Jun 03, 2023 8:36 am

IMG_2441.jpeg
Timing gage

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Re: Question re setting timer position at full retard…

Post by JTT3 » Sat Jun 03, 2023 10:01 am

Dan you’re just showing off ha. You have so many cool T tools my friend.

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Re: Question re setting timer position at full retard…

Post by Chris Bamford » Sat Jun 03, 2023 10:51 am

Thanks everyone for your comments.

Scott, that makes perfect sense and I have known that but forgot it. Yes, with minimal coil TTF variance, the ignition should fire pretty much evenly on Mag.

Speedy, excellent suggestion to rotate the time cover 180° and re-check at full advance. Results are in the photo, far left.

I replaced the new roller timer with the previous, used, TW timer. Much less variation from one cylinder to another (beige tape in photo). I find it remarkable there was this much variation in a brand new roller timer. No surprise the timer industry was a big, big business back in the day!

26T Static timing2.jpeg


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Re: Question re setting timer position at full retard…

Post by Dan Hatch » Sat Jun 03, 2023 2:45 pm

John : Just trying to show guys what to look for at swap meets. Or when my daughter has the auction.


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Re: Question re setting timer position at full retard…

Post by speedytinc » Sun Jun 04, 2023 10:59 pm

Scott_Conger wrote:
Fri Jun 02, 2023 7:39 pm
Chris

when on battery, the plug fires exactly when the contact is first made on the timer housing and if that housing has any built in errors, then the plug firing (timing) will reflect those errors

when on MAG, the plug can only fire on sine wave output of the coil ring (and a contact is made in the timer concurrently), meaning, just because the roller/flapper has JUST made contact, no plug will fire until (while on some portion of the contact) the magnets pass a pole face on the mag ring. Ron Patterson did a very good paper on this and is worth researching on the forum

Note: if there are errors due to misalignment of the timing cover or a mechanical error (such as bent ANCO tab) then when on battery, no coil tuning whether by amperage or TTF will make the car run its best as you are at the mercy of whenever the timer first makes contact...however when on MAG, because the firing is dead even due to sine wave input from magneto assembly, then a very accurately tuned coil will result in a very accurately firing plug.

This is why when on battery, every tiny bit of timer lever movement results in spark advance, and when on MAG, you can move the timing lever through quite a range of movement (several notches) and nothing changes until a significant movement of the lever occurs...this change being the timer having finally moved enough that the advancement of the timer is sufficient to catch the earlier occurring sine wave crossing, or "node" as described by Patterson.

Don't sweat this thing and enjoy your tour.

Patterson's excellent paper describing how the ignition system works: ignition2.pdf


Timer error is most important when running on battery for those that dont have a strong working magneto or prefer the more flexible timing fire between the 22.5 degree nodes. That applies to a good number of T's out there.

Running on magneto there is typically 3 nodes. 1) retard for starting & steeper hills. 2) driving node. where one would typically set the spark for general driving & 3) a more advanced node for higher speeds(rpm's)
If you put an AC volt meter in play, you can find the sweet spot in the middle of a node for maximum mag output voltage. Otherwise you set the spark where you feel the motor runs best. That may not be @ the peak voltage. The voltage is on a bell curve.
Say your mag puts out 20 V. A good feeling running position may be in the 15-20-15 voltage range on the bell curve. You are guessing. As you read the meter you will notice voltage variations in the node. As you leave node 1 the voltage hits a dead spot as the polarity changes. you will see a bounce around zero & the motor runs crappy until you are committed to node 2. As you advance, the voltage rises to its peak @ 20 V (the sweet spot) As you advance further, you leave the sweet spot for a lesser voltage. You may run strong until the voltage drops to 10-8 V.

The problem of a very inaccurate timer is that as, for example, you leave node 1, getting into node 2 you could be firing a cylinder in retard node whall the other cylinders are in the advance node. If the error is not too extreme, when you get closer to the center of the node you be firing all in the same 2nd node.
The same condition can exist as you get past the peak in node 2. You go a bit too far, you can get a cylinder firing in node 3. You will feel the rougher running & will put the spark up a bit higher. In these examples one could be narrowing the area in a particular node where the T runs well.
You can read this error on your volt meter. The needle will be jumping between a positive & negative reading. With an accurate timer. Accurate enough to not be firing a cylinder out of the expected advance node during the transition from a polarity to zero to another polarity will result in a smoother running motor during that transition.
I dont know @ what point extreme timer error becomes an issue on mag. I suspect around 10 degrees error or better.


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Re: Question re setting timer position at full retard…

Post by nsbrassnut » Mon Jun 05, 2023 5:57 pm

Hi Chris

Just for some fun, here is how some of us do it on the East coast side of Canada.

Since my T is a RHD Canadian and the timer rod goes to the bottom of the timer instead of the top, the usual guides don't easily work. And I also installed a split aluminum pulley on the crank, which can be put on in two positions 180 degrees apart by the way.

I followed the suggested simple process noted by others above. Take out the #1 plug and use a wire, gauge, screwdriver or other favourate way of checking piston position. Turn the engine to the #1 compression stroke, piston 1/4 to 1/2 inch down after top dead center. This likely works out to only 2 to 5 degrees after top dead center. But it works well.

Set timer and rods to spark the coil at full retard on the column at this position. Take out piston position indicator, install plug and start engine and go driving.

I'm currently using an old original but still round roller timer and the engine starts easily ('15, non-starter car) and overall runs fine.

Some others here use the modern flapper timer and like it. But they have also had to set them on a home made test rig and adjust the timer arms as needed to get the spark actions to be at 90 degrees to one another. Most of their timers have not been "accurate" in the as received condition.

Eventually, when the roller timer gives trouble, I do have an I-timer on the shelf for future comparison. But so far it runs well enough to keep me happy so I have left it alone for now.

Have fun.

Jeff

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Re: Question re setting timer position at full retard…

Post by Mark Nunn » Mon Jun 05, 2023 9:13 pm

nsbrassnut wrote:
Mon Jun 05, 2023 5:57 pm
Turn the engine to the #1 compression stroke, piston 1/4 to 1/2 inch down after top dead center.

Jeff
No. No. No.

With a stock crank and connecting rods, 15 degrees after TDC is when the piston goes down .087 inches. 1/4 - 1/2 is waaaaay too far.


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Re: Question re setting timer position at full retard…

Post by Scott_Conger » Mon Jun 05, 2023 11:02 pm

Mark

assuming oil gap between moving parts is "0" displacement, it's .093 but you're a lot closer than Jeff, and I'd be happy to crank your car any day! :D

it got too complicated for this simple guy and a pencil and paper, and I had to rely on a piston movement calculator, so I cheated... :lol:
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Re: Question re setting timer position at full retard…

Post by Mark Nunn » Tue Jun 06, 2023 8:22 am

Scott, I did some of that engineer sh1t and made a simple 2-D drawing of piston travel. I did this back when I modified a dial indicator with an offset tip. Zero lash and 15.5 degrees ATDC is .093". I attached a pdf of that drawing. (Who needs pencils when you have full-feature design software at your fingertips.) ;)
TDC.gif
Crank timing.pdf
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Re: Question re setting timer position at full retard…

Post by nsbrassnut » Tue Jun 06, 2023 12:37 pm

Hi Mark

Agreed, 1/2" or so is way far retarded. And too much retard will make them very hard to start, especially on the hand crank. I actually target near TDC on my own cars. So please ignore my earlier comment on piston position.

So to help with the discussion I went out this afternoon and actually measured (more or less) where my '15 is currently set for full retard.

I think that I originally targeted TDC or where the piston just started to move down. Its current setting is actually slightly BEFORE TDC to fire the coil on battery. The coil is firing about 1/16" +- before TDC. And even there I can choke the engine cold, turn 5 spins full throttle, then turn the throttle back to 1/2 or so, and get a free start 4 times out of 5 cold. And it will start hot with only a pull or two and needs very little throttle to start hot.

And I haven't experienced any "kick back" hand cranking with it in this position either. Although I would recommend aiming for more for TDC or just where the piston changes direction.

Here is a picture of where my crank is when the coil is firing on battery. And also one of my low buck home made piston position indicator. A pipe plug with a small holed drilled in the middle and a coat hanger wire indicator. The top of the wire is bend over to point in the same direction as the wire that will sit over the piston so that you can check that its aligned.

Drive Safe

Jeff
Attachments
Ford piston gauge a.png
Ford crank position a.png


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Re: Question re setting timer position at full retard…

Post by Scott_Conger » Tue Jun 06, 2023 5:37 pm

I haven't experienced any "kick back" hand cranking with it in this position either.
Jeff, you will, eventually as it is a mechanical and statistical certainty. With only the slightest wear in the linkage, your timer will be even more advanced than it is and it is going to bite you. With a hand crank car, I'd really suggest that you rethink your position ;)

For those with good insurance an high tolerance for pain, timing the car at TDC is how you get the most performance and greatest advance possible when running on a 6V battery and has been the "secret" performance improvement of many "T" owners for years. I would not recommend it. And, I'd advise folks who do, to only use a starter and keep a repairman's phone # close at hand!

There is another 6V performance "secret" which involves coils but I do not wish to bat that bee's nest today.
Last edited by Scott_Conger on Tue Jun 06, 2023 10:40 pm, edited 1 time in total.
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves
Obsolete carburetor parts manufactured


Jerry VanOoteghem
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Re: Question re setting timer position at full retard…

Post by Jerry VanOoteghem » Tue Jun 06, 2023 7:16 pm

nsbrassnut wrote:
Tue Jun 06, 2023 12:37 pm
Hi Mark

Agreed, 1/2" or so is way far retarded. And too much retard will make them very hard to start, especially on the hand crank. I actually target near TDC on my own cars. So please ignore my earlier comment on piston position.

So to help with the discussion I went out this afternoon and actually measured (more or less) where my '15 is currently set for full retard.

I think that I originally targeted TDC or where the piston just started to move down. Its current setting is actually slightly BEFORE TDC to fire the coil on battery. The coil is firing about 1/16" +- before TDC. And even there I can choke the engine cold, turn 5 spins full throttle, then turn the throttle back to 1/2 or so, and get a free start 4 times out of 5 cold. And it will start hot with only a pull or two and needs very little throttle to start hot.

And I haven't experienced any "kick back" hand cranking with it in this position either. Although I would recommend aiming for more for TDC or just where the piston changes direction.

Here is a picture of where my crank is when the coil is firing on battery. And also one of my low buck home made piston position indicator. A pipe plug with a small holed drilled in the middle and a coat hanger wire indicator. The top of the wire is bend over to point in the same direction as the wire that will sit over the piston so that you can check that its aligned.

Drive Safe

Jeff
And, this is why I never like to crank someone else's car! I have a friend who's car tried to bite me twice. He claimed, "oh, it's never kicked on me..." Uh huh...


robert daniello
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Re: Question re setting timer position at full retard…

Post by robert daniello » Tue Jun 06, 2023 9:36 pm

Although I have not tried, it should be simple enough to redesign the linkage arm to achieve full retard at start and full advance on the hand lever. Doing so may require driving with the spark lever a bit more and backing off on the timing when the engine is at low speed. With all of the "improvements" out there this one should be easy to undo without irreversibly altering the car.


Scott_Conger
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Re: Question re setting timer position at full retard…

Post by Scott_Conger » Tue Jun 06, 2023 9:50 pm

That's a great idea, and perhaps that's why the car was designed to do just that, late in 1908. ;)
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves
Obsolete carburetor parts manufactured


robert daniello
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Re: Question re setting timer position at full retard…

Post by robert daniello » Tue Jun 06, 2023 10:07 pm

The increased travel may still not be enough for some...Regardless with modern fuel and at the relatively higher speeds that we are using these cars today a bit more advance should be perfectly acceptable, provided that it can be done without affecting timing at start and low rpm...


Scott_Conger
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Re: Question re setting timer position at full retard…

Post by Scott_Conger » Tue Jun 06, 2023 11:02 pm

Is 64 degrees advance as designed, not enough advance?

at higher speeds, the time it takes for the coil to actually fire is a significant consideration and the solution to faster firing, is higher voltage...surprise, surprise, the magneto does just that
Scott Conger

Tyranny under the guise of law is still Tyranny

NH Full Flow Float Valves
Obsolete carburetor parts manufactured


nsbrassnut
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Re: Question re setting timer position at full retard…

Post by nsbrassnut » Wed Jun 07, 2023 6:49 pm

Hi Scott and all

I went out and re-adjusted my timing linkage today to get the full retard to be very slightly after TDC where I had originally set it. A bit of play developed over the last few years which I had not noticed as it was working well. To go much further will need me to make a new rod to the timer. The RHD timer rods are straight with a threaded end swivel at the bottom of the steering column.

And a note back towards one of Chris's earlier questions.

My current timer is an old original RHD timer that is in good condition. RHD timers haven't been available for some time so I would consider it either "factory" or "in period" in manufacture. And based on the hand crank position, the 4 coils fire in nearly identical positions so the timer was made fairly well.

I'm current running a correct rebuild Holley G, rebuilt coils (that all pass the EECT test), aluminum pistons and an otherwise stock rebuilt engine. And so far it runs just fine for me. I wanted to start as near stock as possible to see what the car would have been like back then. Then if something becomes an issue, then I'll consider an "upgrade" if needed.

Drive Safe
Jeff

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