Torque against RPM

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Model T Ford Forum: Forum 2012: Torque against RPM
Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Allen Vitko on Monday, May 21, 2012 - 01:48 pm:

Where I live and drive its flat except a few miles inland.

Most of my driving is short runs usually at 35-45mph. Some times the speed gets over 50mph for a few miles to get out of traffic behind.

With an over and under I can lower my rpm's BUT my thinking is with a well balanced engine and transmission and a 26 crank I am better off to spin the engine with more rpm's then twist that crank any more then necessary.

What do the Montana 500 boys do?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Huson, Berthoud, Co. on Thursday, May 24, 2012 - 04:25 pm:

Paul Vitko:

I am not sure what you are asking. You can not use auxillary transmissions in the 500. I don't know what the RPMs are but I have seen 70MPH downhill with everything pretty well stock. The first three motors are torn down at the end of the race and go/no go instruments are used to check every thing. The carbs are checked with a go/no go before the race. The carbs, heads and oil pan inspection plates are sealed before the race. If the seals are found broken after the race you are given the slow time for the day plus one hour
racer


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Huson, Berthoud, Co. on Thursday, May 24, 2012 - 04:34 pm:

racer

stay on the porch


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Thursday, May 24, 2012 - 05:05 pm:

Stock gearing is 40 rpm per mph.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Huson, Berthoud, Co. on Thursday, May 24, 2012 - 05:35 pm:

If that correct,it sounds like 2800 RPM to me. All I know is that the motors are screaming from the time the flag down to the time they go down again. Racing in the Montana 500 is most fun I have ever had with a Model T. I especially liked drafting.

fender to fender

We raced fender to fender for 20 some miles and could not shake the other. We were so close at the next pit stop that they gave us a tie.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Thursday, May 24, 2012 - 07:28 pm:

I prefer stock gearing for stock cars. I think 3.63 is really about as good as you can get. If I had to choose some other ratio, I'd go with 4 to 1 rather than 3.25 or 3 to 1 or 3.08, or any other tall ratio. I don't like aux. trannies, as they rob power and are a pain to drive with, in my opinion.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Allen Vitko on Thursday, May 24, 2012 - 08:30 pm:

I am not racing in the 500, My interest is making the most with what I have to work with.
My bride and I love to garage sale often finding tools parts etc folks would not bring out without seeing the T pull into there driveway.
Astoria is very steep some hills are likely 40 percent the under drive is sometimes used up or down those hills even with disc brakes. The overdrive is almost never used because the stock 3.63 is right for most conditions.
The old saying with garage sales is you snooze you lose so its pedal to the metal from one to the other sometimes a few blocks or other times ten miles.
My question is I think its easier on the engine with good balance to spin it then to gear up and lug it. Most or should I say many drive slower then my comfort level usually 35-55mph on the flats between Seaside, Warrenton, Astoria and Knappa.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Huson, Berthoud, Co. on Thursday, May 24, 2012 - 08:58 pm:

Paul Vitko:

If you can do 55 you would do well in the Montana 500 if you are stock. You ought to give it a try. Most of those that do try the Montana 500 are addicted and return no matter where they finish, its that much fun. The first year I went up I took my old heavy Center Door. I could not qualify for placing in the race because I had a Haibe Head and a Borg Worner Overdrive. But they logged me out and kept my time anyway. I ran fender to fender with a Doctor out of Livingston Montana. We flagged out at Big Timber. After the pit stop I got in a four way hook up with some others up a long steep hill into Bozeman. Finally near the top the guy I was hooked to from California dropped out and I was done for. I enjoyed the race so much that I went back home and started looked for T to build for the race. I ended up going to 12 races. Try it you will like it. By the way I finished 7th in the race.
A365c


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Allen Vitko on Thursday, May 24, 2012 - 09:21 pm:

If my ship came in with Bakken oil rights in ND the 500 would be a blast even just meeting folks in person met on the forum.
Its differant strokes for differant folks so keeping my bride happy and having some T time just talking T stuff with many folks is my fun!!
Folks down from Portland rarely if ever see a 22 touring doing fifty down the road!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Darin Hull on Thursday, May 24, 2012 - 09:48 pm:

Do the T's in this 500 deviate from stock when it comes to brakes? I was curious with the speeds at 50+ if folks relied on something other than transmission bands.

Darin


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Thursday, May 24, 2012 - 09:56 pm:

We have stock brakes, but don't use 'em. :-) Stopping is way over rated in my book. On the highway you rarely use your brakes. In town is more where you need them and a following distance and vigilance can make up for sketchy brakes.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Allen Vitko on Thursday, May 24, 2012 - 11:26 pm:

True to a degree Tom but have a stupid elk, deer, or dog jump in front or get half way up a steep hill and have to stop for a kid chasing his skate board across the road and my Honda disc brakes make me very happy!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Friday, May 25, 2012 - 02:55 am:

Paul, of course stuff can happen. Do you really think that your Honda brakes will make a significant difference if something jumps in front of you?

I wonder if anyone has done any tests comparing stock brakes to the various aftermarket brakes, or do they just assume that they are better?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Friday, May 25, 2012 - 06:59 am:

Tom

That would be interesting.

Data from early source , M Fahenstock, made list of stopping distances for the T. Common one is traveling 20mph in a T, it takes 35 feet to stop.

Empirical feel of the Rocky Mtn brakes on my '27 over the stock brakes on my '24 to me seems to make the outside rear brakes added to be better in stopping. But haven't done a test on the road.

Two chalk lines in the pavement 35' apart down the level neighborhood street should be a good test track :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, May 25, 2012 - 07:33 am:

We discussed this at length mebbe a month ago. With the tranny brake only, you will slow in a straight line, and the distance depends on the wheel with the least traction.

With rear wheel brakes, one wheel losing traction causes the car to swerve.

Front brakes are the worthwhile upgrade.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Neil Kaminar on Friday, May 25, 2012 - 07:55 am:

If it is 40 rpm per mph, at 10,000 rpm you would be going 250 mph.

Neil


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Friday, May 25, 2012 - 08:15 am:

:-) Wonder at what rpm the magnets starts flying through the hogshead?


Top of pagePrevious messageNext messageBottom of page Link to this message  By George_Cherry Hill NJ on Friday, May 25, 2012 - 09:06 am:

Roger,

I think they come through just after the flywheel explodes due to the tangential stress limit letting go at the press fit triple gear pins. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Allen Vitko on Friday, May 25, 2012 - 10:11 am:

All of the mentioned reasons for brakes have happened to me. Ones not mentioned are being cut off with distance behind a car ahead with a car passing me gaining 50 feet and a string of cars a mile ahead of the passing car.
Other times moving with the traffic at 50 a light changes to yellow and the one car ahead plants his brakes hard with plenty of time to go through the yellow light.
During the summer many folks come to fish, clam, and crab. They are un familiar with the area and do some strange driving.
The one single best modification done to my T is disc brakes, I can relax where before some drives were much slower and white knuckle


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug - Braidwood (glow in the dark), IL on Friday, May 25, 2012 - 05:59 pm:

Paul, not to sidetrack the discussion, but your statement "The one single best modification done to my T is disc brakes, I can relax where before some drives were much slower and white knuckle" is exactly what concerns me. Now, you will drive as though you have brakes and you really don't know how much your stopping distance has changed nor what the car will do in the above panic scenarios.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Allen Vitko on Friday, May 25, 2012 - 09:42 pm:

My discussion was wanting to know if spinning the T engine was easier on the crank then using a high gear slowing the engine down but twisting the crank more with torque to keep up the speed.
In a stock T after you drive it for a while you know its limitations.
After going to disc brakes and I am sure after using front brakes or rockies you know there limitations.
I have not stopped on a say 40 percent hill with rockies or driven in wet conditions but I have with discs up down or backward with no problems.
They are not like modern car brakes but one hell of a lot better then stock T. So no! I do not know!! Use what you want and I will use what I want.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Saturday, May 26, 2012 - 10:05 am:

Failure limits of any forged steel crankshaft are going to be met more quickly by increasing either frequency (RPM) or force (ft - lbs of torque). Your Model T will last longer if you treat it gently. There's not going to be any particular advantage to high RPM instead of finding a way to develop the same amount of power at lower engine speeds.

In general, raising compression and increasing air flow in an internal combustion engine will increase torque at lower engine speeds.

Specifically, one of the aluminum high compression cylinder heads and a modern camshaft grind will make more power at the same RPM. Increased valve diameter helps too. None of these things are legal for the Montana 500.

All of these things have been done to my '15 touring. I typically cruise at 30 - 35 MPH for longevity and safety's sake. The suspension, brakes, wheels and tires are not safe at higher speeds, although this T will easily top 50 MPH. I am much more interested in reliability and being able to climb any hill with four adults on board than I am in achieving unsafe cruising speeds.

Spinning the stock engine faster is not too effective and is generally a recipe for rapid engine failure.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Saturday, May 26, 2012 - 10:11 am:

In general, raising compression in an internal combustion engine will increase torque at ALL engine speeds.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Saturday, May 26, 2012 - 10:22 am:

Ralph - Agreed. Increasing cubic inches also raises torque at all engine speeds.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug - Braidwood, IL on Saturday, May 26, 2012 - 11:25 am:

Paul's question remains, is it harder on the engine to increase torque or harder on it to spin it faster?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Saturday, May 26, 2012 - 11:41 am:

What is the weak link in a T engine? It has to be the crankshaft. Which is worse, flexing it a little real fast, or flexing it more not so fast? It may be a wash.

With a well balanced engine as Paul has, I prefer spinning it faster. YMMV

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Saturday, May 26, 2012 - 07:40 pm:

Doug - my answer was that the Model T was designed for low end torque. Higher RPM is not a good idea, notr are higher road speeds. I do wholeheartedly recommend balancing the engine and transmission. It is mandatory for any T engine I rebuild for myself. It adds longevity.

You don't know when a T crankshaft will break, but you know it will some day.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Allen Vitko on Sunday, May 27, 2012 - 09:55 am:

Mostly agree with you Royce, I would just as soon drive at 40mph but a stock T is like a black powder gun hunting elk, you had better get your one shot right with today's speeds!
If I lived where Ralph lives my T would have front brakes and a 25 pound Chev crank.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Sunday, May 27, 2012 - 10:21 am:

I look at it this way Paul - if I want to drive 50 - 60 MPH I will buy a Model A.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Allen Vitko on Sunday, May 27, 2012 - 11:10 am:

Not my bag Royce, Model A-s look to much like a real car. Had a 29 tinker toy roadster for years.

The T I am excited about is a 16 blacksmith built roadster pickup. Its going to stay with the dents and bailing wire but run well. I have a nice running board tool box but the bent box used for a step stool looks much better. A vintage doctors bag will set next to it holding the battery for the 26 engine. Brakes will be Honda with 11 3/4 rotors, my 22 has 10 7/8 rotors
Bet it will grab as much attention as a perfect T. and the box will hold lots of garage sale stuff.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Monday, May 28, 2012 - 07:50 am:

Not to change the tack of this thread, but I feel the need to disabuse people of the notion that "speed kills" in a Model T.

Royce said: "I am much more interested in reliability and being able to climb any hill with four adults on board than I am in achieving unsafe cruising speeds."

I think that most serious T accidents happen because of travelling too slowly in a T. I have had two friends involved in very serious accidents in T's where they were rear-ended. The cause of this kind of accident is directly attributable to driving too slowly. I can't think of any serious T accidents (in a stock T) that are directly attributable to driving too fast.


Since I'm posting, I'll give my opinion to the subject at hand. I think that high speed (assuming proper lubrication) is no real problem as long as you avoid the "thrum" speed. The "thrum" is a harmonic that all T's have at around 2000 rpm's. I have T motors with 10's of thousands of miles that have been driven fast all along the way.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money - Braidwood, IL on Monday, May 28, 2012 - 10:08 am:

Tom, does balance affect thrum? Can you drive through thrum where it disappears at a higher rpm?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Allen Vitko on Monday, May 28, 2012 - 11:17 am:

Thanks Tom! That's what I was trying to learn at the start of this thred. Who better to ask!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Monday, May 28, 2012 - 12:04 pm:

Doug, two jolly good questions. I will answer the second one first.

Doug asked:"Can you drive through thrum where it disappears at a higher rpm?"

Yes! If you have enough power. If your thrum is just below your top speed, it is very, very difficult to push through it. It takes a bit of extra power over and above to push through, but once you do, you have a little extra to stay above it.


Doug asked: "does balance affect thrum?" I am not sure. My gut reaction in that it has little effect on it. I would think any dampening would help reduce thrum. For example, loose bearings would tend to allow more thrum I would think.

Just thinking back on my three Montana 500 motors (which are all well balanced): Number one, which was in Tweety Bird, that I used to win in 1977, has hardly any thrum at all. This is the car that I gave to my sister, which she won with a couple of years ago. My second car (Bear Mobile) had a horrible thrum at about 52 mph. Just the speed that you spend a lot of time in at the Montana 500. One year I drove it hard at thrum speed (I was trying to catch the car ahead of me while fighting a headwind) and broke the crank. I replaced it with an early "diamond web" crank, and the thrum went from 52mph to 47 mph. That was a nice thrum speed. Some jerk then complained about that crank, so I replaced it with a "square web" (26-7) one. The thrum is now at 51 mph, and quite light. My newest car has a 26-7 crank and a light thrum at 51 mph, which I can usually push through.

In summary: The thrum seems to be a function of the crank, which lends credence to Ralph's contention of the superiority of the Chevy crank, at least in this area.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Money - Braidwood, IL on Monday, May 28, 2012 - 12:58 pm:

When it comes to highest rpm, if one switches to a SCAT or Chevy or A crank, does the crank type seem to be the limiting factor on engine speed? I imagine babbitt will only tolerate a certain rpm, is there anything else? What rpm do the Montana cars run at?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Allen Vitko on Monday, May 28, 2012 - 02:26 pm:

Its interesting to me after weight testing the twist and bend in early or late cranks the early ones say 22-25 test weaker then 26-27. The early T 498 crank like in my 16 engine tested the weakest of all the cranks tested. Two of the T 498 cranks were tested.
If you weigh the cranks the early ones are the lightest at about 14 pounds with the 26- 27 cranks at about 15 pounds.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Tuesday, May 29, 2012 - 04:10 am:

Doug, I can't answer your first two questions because I don't really know. The answer to the third is: "about 2000 to 2200 average, maxing out at around 2800".


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Tuesday, May 29, 2012 - 04:33 am:

Thanks Tom for your valuable input :-) Your talk about "thum" reminded me about Reid Welch's excellent discussion on the problem with Dunn weights for T cranks, preserved at the Montana 500 site among other excellent T tips from the early days of the forum: http://www.antiqueautoranch.com/montana500/adrian/webinfo.html

"DUNN weights. Some guys swear by them! The weights were a great seller 80 years ago, and many sets were sold. I bought into the hearsay and ad. testimonials. I installed a pair. I put them on right. I spin balanced the crank to 5k. Perfect. I felt the car ran like gangbusters and was very happy and smug for a while. Later on I realized the hidden danger of counterweights on a stock T crank. I took them off. Even though I _thought_ the car ran smoother with the counterweights- once they were gone- what was this? the car ran just as well, if not better. I was fooled by the famous Placebo Effect. But I took the Dunns off for a seriously scary good: I'd finally figured out that the extra mass of the weights, which are nothing but extra flywheels distributed along the crank, caused the bent wire T crank to twist and squirm very severely at certain engine speeds. Twist and untwist as it never did before. Added counterweights can very well wear out a T crank. Meaning, it breaks without warning.

Ask around about a real, aftermarket counterweighted crank made in the 1920’s- it was a big seller, and not Mickey-Mouse looking like the bolt on Dunn weights. It had integral, forged counterweights of much smaller mass than the Dunn weights. This "SureMike" crank promised you'd "Run faster with less vibration", and indeed there was merit to SureMikes's claims. It would be better named, however, "SureBreak" because they have a reputation for letting go sooner or later. Why? Maybe the forging wasn't equal to Ford's work... OR.... Analysis of the problem involves explaining some basics about the behavior of a crankshaft in the running engine. It is long, it is skinny, it is undamped at the forward end. It has crooks or bends and forging flaws and usually, hidden cracks due to long use and old age. The crank throws receive terrific power impulses, reoccuring in a certain order. Each explosion forces a twist into the springy crank. This is a torsional vibration. If the torsional vibration becomes large in amplitude the crank will quickly fatigue, much as when you bend a paper clip back and forth. Hopping up a T engine to produce double it’s stock horsepower is a good way to break a crank. The metal only knows twist. More twist less life span. This is why modern cars and quality cars of olden days have much thicker cranks than in the T, to reduce torsional flex.

Another crank-breaker is harmonic vibration. Any object that can be flexed has what is called a "natural period of vibration". A piano string has a natural period of vibration- for that is where it will vibrate with greatest amplitude with minimum power input. So does a wooden yardstick clamped to a table edge and sprung by the hand.

A crankshaft, loaded with reciprocating pistons and rods, and having a number of kinks and changes of cross section along its length also has a natural period of torsional vibration- perhaps several! In practically every engine, the rear end of the crankshaft is loaded (or constrained) by a massive flywheel. The flywheel cannot suddenly reverse its direction. And even though torsional vibrations will not be reduced one bit, the flywheel checks harmonic vibrations. In practically every modern engine, we find a "harmonic damper" attached to the free, front end of the crank. Whatever it’s design, the harmonic damper’s job is to absorb torsional movements at the end of the crank. The T has no harmonic damper, which is a bit of a shame, because it would really benefit from a damper. Now, what happens when we add upwards of 16 pounds of rotating mass to the flywheel, distributed between the one and two and also, between the three and four cylinders? The harmonic resonance point of the engine has been drastically altered.

When harmonic vibrations occur- and they occur just as they did before, only at different bands of engine rpms- the extra mass of the Dunn weights makes the crank suffer far larger harmonic excursions than before. Like this rough example- extend your arm outward and wave it up and down through an arc of six inches. Do this as fast as possible. Next take a weight of some sort in the hand and repeat the test, trying to get the same up-down speed and keeping the same restricted arc of motion. You cannot- not without using much more muscle! The T crank does not have muscle; only springy steel. And so, the result to the T is that the torsional vibrations increase in amplitude. I found in my own car that at a road speed of 42 mph the harmonic vibrations became so powerful as to make the whole engine and car thrum very loudly. This was a dynamically balanced crank, btw. One night I was out doing a speed run and when passing through that critical speed of 42-45 mph the fiber timing gear suddenly was stripped of its teeth. I had to get a flatbed ride home. The Dunn weights did it. How? Because at the critical speed of resonance the back-and-forth _shimmy_ at the front end of the crankshaft actually turned the steel crank gear into an immensely powerful battering ram- to the fiber timing gear. It fractured a fiber tooth and that spelled destruction for the remaining teeth. Wham! What a noise it made at 45 mph!

When replacing the timing gear with yet another fiber gear I pulled the lower cover to clean out the gear debris. And take off the Dunn Weights. Next ride I found there was no more distress at 42. None at all. As I said, even a stock crank has considerable periods of harmonic vibration. They are made much, much more intense

by Dunn counterweights. On my own car the barometer of harmonic activity in the crank is my fan belt. Yet- seriously. My fan belt runs tight. It’s treated with an anti-slip compound. It runs straight and true on a ball bearing fan hub. I drive with the hood off, and I can glance at the belt while driving. At several road speeds the belt can be seen to flutter. I avoid steady driving at about 32 mph, for instance, because this is a belt fluttering speed. Close the throttle and the flutter instantly stops. Open wide, and the flutter gets worse- but only over a road speed band about 2mph wide. With the Dunn weights that flutter at 42 mph extended up to 45 mph. The belt whipped and flapped so violently that I thought the loud thrumming noise must be from the belt itself! It was not. I slipped the belt off the pulley and ran up the critical speed again. No belt, and the thrumming was louder than ever. I determined in fact, that a low-slip fanbelt actually confers a very useful degree of harmonic damping to the T crankshaft. Harmonic damping is a good thing. Much more recently I read in a book on vibration theory that close coupled engine accessories do indeed help damp the crankshaft contortions. The harmonic damper is better, however, because it is a full time, purpose built device. If one carries this logic to it’s conclusion, it is quite clear that if a crank is so heavy and beefy that it twists very little, it will hardly ever fatigue. If it is twisty as a paper clip, and you force it to twist further than intended it will break sooner than later. Dunn counterweights force the T crank into much larger torsional excursions at resonance. Similarly in a sense, doubling engine HP forces larger excursions at all rpms. But even at double HP, the maximum excursions of the stock crank in a highly hopped engine by my guess are not so severe as those brought on by the heavy Dunn weights in a 20 HP T running at the critical speed of forced harmonic vibrations.

What the T needs is not counterweights. It needs a thicker crank. Reid"




Model A Fords has better oiling for the mains and generally a heavier and stiffer crank - does anybody know what's the typical top rpm a model A can withstand for cross country driving?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Vince M on Tuesday, May 29, 2012 - 10:22 am:

I think the T crank gets a lot of wear and tear and flex from a considerable amount of engine braking typically done to save the bands.

Regarding the speed vs. torque, without any testing i would defer to the cars intended design as the most favorable - which is low RPM's.

In addition, a break at high rpms has the potential for much more collateral damage.

Vince


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie on Tuesday, May 29, 2012 - 10:59 am:

Roger, very interesting! Also note that the force at harmonic resonance can exceed the input force. It is a function of the q-factor of the resonating member. Q-factor is the amount that the system is underdamped. An example of an underdamped system is a bell. A bell with a cloth over it would have a lower q-factor. A front end that shimmies has a high q-factor. A front end with a steering stabilizer has a low q-factor.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Allen Vitko on Tuesday, May 29, 2012 - 11:07 am:

Very interesting post Roger!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Allen Vitko on Tuesday, May 29, 2012 - 11:31 am:

I think someone needs to invent a simple thrum gage for us folks using a stock T crank. I drive with a hood and am to busy watching for other issues.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Tuesday, May 29, 2012 - 06:41 pm:

I think what needs to be said is Reid could invent a justification for any scenario without regard for the facts of the matter. While I have to admit Reid had a way with words, I disagree with the premise of his arguments in many cases.

Reid's fiber timing gear did not die because of anything named "thrum". It died because it was a fiber timing gear.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Tuesday, May 29, 2012 - 09:39 pm:

Roger, your whole post is clearly Opinion on your part, which is fine with me, but it has nothing to do with reality, or any kind of fact for any engine, not alone a Model T which needs it the most.

To get the most Longevity out of any engine, is Balance, Balance, Balance!, and that is assuming every thing else was done the way it should be.

I will use Dunn Weights as an example, as I have used in some of our engines about 84 to date, all balanced afterward, except my first set at 19, when I put on a set on my center door, with out balance. I would not run a Model T of my own, with out a Balanced crank.

The Power stroke of the first rod does tend to impulse and want to twist the crank, but with say the Dunn weights, they counter act the impulse, and Dampen it, and also reinforce the web between 1&2, and 3&4 Rods, by being clamped there.

Roger, there are so many variables that you formulated your Opinion on, with out there consideration.

Like, and one of the most important, was your crank ground on the exact center line, was the center main ground and pushed out, and if its is it an old rebuild, is the align bore still true, or does it have a lot of miles on it.

I have looked on, and off since this morning, and I finally found an article, that explains it all, it is on Model T's also, but as I said it holds true for all engines, of this type.

The book is The Model T Ford Owner, by Murray Fahnestock, Pages 360, to 366. There is just no argument that can be used against balance!

Herm.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kohnke Rebabbitting on Tuesday, May 29, 2012 - 09:42 pm:

Royce is right on the Fiber Gear.


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