Advancing cam gear

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Model T Ford Forum: Forum 2005: Advancing cam gear
Top of pagePrevious messageNext messageBottom of page Link to this message  By Ross Harris on Thursday, January 24, 2008 - 07:54 pm:

I read on hear sometime back about advancing the cam gear like to have information how to do this and advantages.Can you buy a gear or do you have to redrill holes in gear thanks Ross


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim ( Gen3AntiqueAuto ) on Thursday, January 24, 2008 - 08:16 pm:

Ross, I use a blank gear and drill my own holes. I also use a degree wheel to set it up right instead of guessing. Advancing or retarding the cam simply moves the "power band" to a different rpm range.

i.e. If peak power is 1500 rpm, advancing x# degrees it will bring it down to 1200 OR retarding a cam x# degrees would bring that peak power to 2000. You also loose a little off the other end.

You can use offset dowel pins, or turn the gear 90 and drill your own holes where you want them.

If you want to advance yours on blind faith, try 1/2 tooth and let us know how it turns out!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck on Thursday, January 24, 2008 - 09:24 pm:

Tim is correct that changing the cam timing moves the power band.

Advancing the cam will not only lower the peak torque speed, it will increase the peak torque. For those of us with no auxiliary transmissions that don't like to wind out low gear, advancing the valve timing can be a step in the right direction.

That is, if you know where you are before you change things, like Tim said. A half tooth is 7.5 crankshaft degrees. I'd probably take a baby step and go one third of a tooth - 5 crankshaft degrees.....Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim ( Gen3AntiqueAuto ) on Thursday, January 24, 2008 - 10:08 pm:

Ross, results will vary too.

I tried 7.5 degrees (a true 7.5, not a guess) on my fordor and it did very very little for me. This is a worn out engine with a vaporizer on it, who knows what the cam grind is. It didn't hurt it any, it just was not worth the effort.

On a customers car, the same 7.5 with a new 280 cam felt like I had added on two extra cyls (the one idling in the video on my website here: www.modeltmotor.com/news.htm ). That car takes off like a rocket.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken - SAT on Thursday, January 24, 2008 - 11:16 pm:

LOL... Don't know about the "two extra cyls" but the 280 cam alone adds nearly two horsepower (10%). It also stretches the torque band out an extra 200rpm and just about reaches the HP peak range. But you loose a little torque (about 6%) on the low end and gain about 6% on the high end. Advancing the cam is probably adjusting the 280 torque curve back in line on the low end.

Simply raising the compression to 6:1 on a stock cam will blow both mods out of the "running". A 25% gain in HP and a 12% gain in torque is not unusual.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jeff Hood on Friday, January 25, 2008 - 12:03 am:

I have no idea of the history or mileage on the engine in my touring. It would easily run to over 45mph, but was weak on hills, and made lots of Model T noises. I don't know how it was timed since the cam nut came loose, and the fiber gear came off of the cam. The nut looked like it had been tightened with a pipe wrench! I put it back together with an original steel gear, and I advanced it 1 whole tooth. (I was in a hurry) It still goes about 45mph, although it takes it a little longer to get there, it hums right along at 40, and it pulls hills much better. Once it finds it's power rpm it just hunkers down and pulls the hill. It has a slight lope at idle, and it still makes a lot of noise.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom on Friday, January 25, 2008 - 08:05 am:

I have had good luck with advancing the cam 1/2 tooth. There are 48 teeth on the cam gear and 7 1/2 degrees between each tooth. One half tooth is very easy to line up using a jig made from an old gear. The angular difference between the teeth for 1/2 tooth of advance is 3 3/4 degrees which will give you 7 1/2 degrees advance in valve timing. It helped a great deal with the low end torque of my touring which has a 3:1 ring and pinion and needed some assistance. I also did the same for a buddy of mine on his depot hack and the improvement was immediatly noticable.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem on Friday, January 25, 2008 - 10:58 am:

My dad did the same thing to our 25 Touring with great results. If I'm not mistaken, I think what some of us would like to see here is for one of the suppliers to offer an "advanced" timing gear, (in aluminum and bronze)? Glenn? Don? Dan?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, January 25, 2008 - 11:08 am:

How about a new gear with three sets of holes, or more?

Dan?

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim ( Gen3AntiqueAuto ) on Friday, January 25, 2008 - 12:17 pm:

I already offer them. But they are the "evil nylon" gears that were mentioned in another thread. I buy the gears a few at a time without any holes in them, if you wanted stock and advanced 1/2, that's easy.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim ( Gen3AntiqueAuto ) on Friday, January 25, 2008 - 12:18 pm:

You can see where I used green for "go", if you look close you see two green lines to show which holes to use (just so there are no mistakes). I wiped them off after mounting. The red dot is the standard timing mark.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe on Friday, January 25, 2008 - 12:34 pm:

Seth, a full tooth is 7.5 degrees, a half tooth is 3.75 degrees, a third of a tooth -- a "baby step" -- would be 2.5 degrees. At least that is the way I figure it. 48 teeth, 360 degrees = 7.5 per tooth.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck on Friday, January 25, 2008 - 12:47 pm:

There are 24 teeth on the crankshaft gear - 15 degrees per tooth. Valve timing is expressed in crankshaft degrees. That's how I figured it and that's why I always like to add the word crankshaft.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom on Friday, January 25, 2008 - 12:50 pm:

I did the same except I engraved which timing mark was stock and which one was advanced. I also marked (engraved) the dowel pin holes so it should be evident to the installer. This particular gear is currently in my car. I bought it from Texas T Parts and it appears to be 7075T6 aluminum.
Gear


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim ( Gen3AntiqueAuto ) on Friday, January 25, 2008 - 01:10 pm:

Gary that is much better diagram than the one I use to prevent mistakes. It explains it well.

And one full tooth is 15 degrees Stan, the cam runs 1/2 speed so your 7.5 is really 7.5 x 2 I get such a headache figuring this out. By the time I do it again I've already forgotten the last time and have to start over.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Bamford on Friday, January 25, 2008 - 01:24 pm:

I'm embarking on a powerplant overhaul for my '26 Canadian touring. This thread has got me thinking about advancing the cam gear a half tooth, and I welcome your comments on how this setup might affect my particular car...

I bought the car two years ago at a local auction. A bit of research turned up the identities of several recent owners and the widow and son of the fellow who restored it in the early '60s. It appears they did decent paint and upholstery/top and maybe touched up the engine, otherwise it's pretty much original. The side curtain parts are all there, along with the tools, rear mat and Henry's own wood throughout.

When the dust settles, the engine will be sporting this Z Head, new valves, aluminum pistons, 280 cam, rebuilt coils, 6vt battery and magneto. I run stock rear gears and brakes with no auxiliary transmission.

My driving is mostly urban -- we live in a river city, right near the valley with a selection of grades only minutes away, and I frequently carry one or more passengers.

In summer, we give countless rides at Fort Edmonton (Canada's largest living history museum) for which smooth low-speed operation and easy crank starts are a must.

So whaddaya think?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim ( Gen3AntiqueAuto ) on Friday, January 25, 2008 - 01:30 pm:

I think you should consider a ruckstell or 4:1 gears in addition to advancing the cam 1/2 tooth. I highly recommend using a degree wheel to verify you have what you want. Just lining up the dots is a crap shoot.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom on Friday, January 25, 2008 - 02:02 pm:

On other thing to consider is the timer rod will have to be bent to compensate for the advance of the cam. The timer rotor advances with the cam which means ignition will also occur 7 1/2 degrees sooner (on battery). Failure to do this may result in a car with no tendancy to kick to all of a sudden kick while trying to start. Just so ya'll know.

If you don't rebend it, when running on mag the timer lever will not be allowed to be pulled down as far as before as the range in which connection takes places has moved.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, January 25, 2008 - 02:52 pm:

Oh, what are all you guys thinking? One change leads to another, and another, and another... Do you really think you can improve on Henry's best?

Seriously, why isn't stock timing the best compromise?

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck on Friday, January 25, 2008 - 03:38 pm:

Fuel quality - low octane may have been the reason that Ford could not advance the valve timing.

More torque is the result of the increase in cylinder charging, so also is higher cylinder pressure and tendency to knock.

We have it made today with modern gasolines. They allow us to fit high-compression heads and advance the valve timing and are perfectly content with regular unleaded after doing so.

My guess anyway!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe on Friday, January 25, 2008 - 03:40 pm:

Well, I'm smarter than I was even tho some of you are talking degrees of advance on the cam gear and some are talking degrees of advance on the crank gear. I'd like to hear what Steve Coniff has to say about all this. He has done mountains of testing on cam timing. Also, the Carnegie brothers have done a lot of testing of various cam timiings in the real world.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom on Friday, January 25, 2008 - 03:50 pm:

In my case (3:1 gears with Ruxtell) the reduction in RPM is fine for high speed running however, at each little hill I would have to shift the Ruxtell to low as the best torque RPM range didn't make the same RPM reduction. With the advanced gear the car is now very equal in torque to a standard ratio touring car which means I don't use the Ruxtell near as often.

I see very little difference in top RPM performance. My car will do over 50 MPH but I rarely drive it over 30-35 as even with Rocky Mountain Brakes you don't have a great ability to stop. I like to engage the low pedal and immediatly step off of it and let the car chug away in high. Couldn't do that before, can now.

BTW, you can't be serious? OHV, 4-wheel brakes, ect., etc. Talk about one mod leading to another.....


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Walker, NW AR. on Friday, January 25, 2008 - 06:52 pm:

Stan -- I bought one of the Carnegies' reground cams for Bev's Huckster. Their recommendation for that cam is to advance the cam timing a half-tooth.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Friday, January 25, 2008 - 07:11 pm:

Gary, it's fun to take the job of Original Cop once in awhile, just to see how the other half thinks...

"The modifications on MY car make it safer, more reliable and improve itís appearance. The modifications on YOUR car are unnecessary, troublesome, gaudy and ruin the whole character of the Model T!" ... . Borrowed from a Model A guy.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan McEachern on Friday, January 25, 2008 - 11:57 pm:

To answer Ralph's question, I can supply cam gears with any advance or retard of the dowel pin holes. It is possible to put up to 3 pairs of holes in the same gear before the space between the holes gets thin. The dowel pin holes on our gears are machined on a CNC mill, so a simple program change can move the holes in fractions of a degree increments. We always try to have gears with blank hubs on the shelf for this purpose.

Just a comment on advancing the cam a whole tooth- I've built well over 200 engines and never have I found it necessary or to advance or retard a cam over about 3 degrees either way to get the cam timing to come in to the grinder's specs.
If your goal is to change valve timing, do it correctly and have a cam ground to your specs and set it according to the specs. There are about a Ĺ dozen things that can have an effect on cam timing- only two of them can be the fault of the gear manufacturer.
I hope this answers some of your questions.
Dan


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les Von Nordheim on Saturday, January 26, 2008 - 02:00 am:

I find the above information to be Good Stuff!! Very interesting. Dan, rdr and others that have walked the walk....The late Fred UpShaw would advance the crank shaft gear 1/2 the keyway thickness on chev crankshafts modified for T's. How does this compare to advancing the cam gear 1/2 tooth as discussed above? I know it is much more difficult to change the crank shaft gear location compaired to the cam gear. I am mainly interested in improving performance on hills....not necessarly going faster on the flat. My T all ready goes fast enough on the flat to scare the "H" out of me..smile! Thanks, "Les"


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Saturday, January 26, 2008 - 02:35 am:

If I ever tear down the Fronty engine that was put together by Fred Upshaw, I'll look at the gear...

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard Gould on Saturday, January 26, 2008 - 11:24 am:

Hey Chris, I am responding to your post where you say:

"When the dust settles, the engine will be sporting this Z Head, new valves, aluminum pistons, 280 cam, rebuilt coils, 6vt battery and magneto. I run stock rear gears and brakes with no auxiliary transmission.
* * * * * *
So whaddaya think?"

With the kind of driving you do, I would substitute a 250 Stipe cam for the 280 you are thinking about. In my experience, there is a let down in performance on a 280 at the shifting point between low and high gear. I do a lot of city/residential driving in gentle hill country with a lot of shifting between gears. I tried a 280 cam and wasn't satisfied, so I pulled it. I find the 250 pulls nicely at low rpm and still has plenty of power at the top speeds I am confortable driving, the 35 - 38 mph range.

I run a Richardo head with coils, an NH carb, a high volume intake manifold and standard timing. I get really nice performance. Nothing earth shattering, but smooth running and shifting with adequate power at all speeds.

Others opinions may vary.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Anthony Bennett - Australia on Sunday, January 27, 2008 - 12:25 am:

Just a thought chaps,

If there were to be an aluminium timing gear made with multiple dowel holes for different cam timing, would it not be feasable to use only one dowel?

Small block ford V8's use only one 5/16 dowel and so with a model T there could be more than 3 positions offered on one gear.

Maybe the cheapest answer could be an offset dowel... how much change could be accomodated with the dowel diameter do you think?

I have noticed a considerable difference in the drillings of production gears... I assume quality control is responsible for that.

I'm off to the shed for a measure up:-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Coniff on Sunday, January 27, 2008 - 02:14 am:

Stan Howe asked me to commet on the cam thread. This imformation should help people understand advancing and retarding of the cam. The two most important events on a cam is the intake closing and the exhaust opening. The intake valve closes at 50 degrees past bottom dead center on a stock T cam. Advancing the cam say 5 degrees would make the intake close at 45 degrees. What advantage does this have? Runing at lower RPM like a T does 5 degrees would give 5 more degrees of piston movement to compress the mixture a little bit more causing more power to be imparted to the piston when ignited. Ed Winfield, in his two up and two down circle track engine closed the intake valve around 33 degrees. He needed the extra power to pull off the corners. Retarding the cam has its advantage in higher RPM use where an engine can really breathe and go fast. Advancing a T cam 5 degrees with stock timing at -10 ATDC and 50 ABDC will give you -15 ATDC and 45 ABDC. The exhaust lobe timing is around 34 degrees BBDC and 0 degrees. With 5 degrees advance the exhaust valve would open at 39 degrees and close at 5 degrees ATDC. What will this do? Holding the exhaust charge in the cylinder a long time will allow the burning charge to impart its power to the piston. It also causes more heat to build up in the cylinder. Holding the charge in the cylinder too long can loose power just as letting it escape too soon will do the same thing. Engines with say 10 to 1 compression can open their exhaust earler than an 8 to 1 motor. This is because the mixture is compress tighter with higher compression and burns faster so you can let it loose sooner. Many engines may open the exhaust at 65 or 75 degrees BBDC. I hope this helps a little. I have some numbers that work well in a T. I will post them, let me know.
Steve Coniff


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Bamford on Sunday, January 27, 2008 - 10:07 am:

Thank you Richard (and Tim) for your comments.

Richard advocates a 250 cam rather than a 280 for my motor, to reduce the low-high shift bogdown.

Comments upthread indicate that advancing the cam gear a wee bit helps low speed torque. Could this then offset the lack of lower after shifting that he saw with the 280 cam?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Trevor Davis on Sunday, January 27, 2008 - 05:49 pm:

Concerning Steve Coniff's offer I would like to see the numbers which he said work well in a T. If possible I would also like to send Steve the numbers measured on my car for his comments but lack his email address. Can someone help?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Trevor Davis on Sunday, January 27, 2008 - 10:25 pm:

As a further comment on the information provided by Steve Coniff I have now got a much better grasp of what effects advancing the cam gear has on engine performance. However I have run into a problem. When I calculate the angular durations that the inlet and exhaust valves are open from Steve's figures it seems that the durations change by 10 degrees when the cam gear is moved by 5 degrees. I am unable to understand why the durations that the inlet and exhaust valves are open should change at all. Can someone figure out if or where I have made a mistake please?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan McEachern on Monday, January 28, 2008 - 01:06 am:

Trevor- most likely you have made an error in your calculations- duration is totally a function of lobe profile and is not affected at all by advancing or retarding the cam. The opening and closing events will still happen the same number of degrees apart but they will be shifted by the amount of cam advance or retard.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe on Monday, January 28, 2008 - 01:33 am:

Steve, thanks for the intelligent and well presented explanation. I'd like to see more of your numbers, knowing that they are based on actual experience as opposed to theoretical hypotheses.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Trevor Davis on Monday, January 28, 2008 - 04:47 am:

To Dan McEachern my thanks for your response - I agree with you entirely and this is exactly my point which you appear to have misunderstood in my statement. It is Steve Coniff's sets of figures that I believe to be in error and which on calculation imply increased durations. If you calculate the durations yourself you will see what I mean. The durations should not alter and on this we are in total agreement. I am hoping that Steve will notice our comments and resolve this anomaly.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mack Jeffrey Cole on Monday, January 28, 2008 - 10:00 am:

Well,I aint a rocket scientist but I do play 1 in the back yard once in a while.What I have fiqured out is no matter where the gear is on the cam shaft,it aint gona change the amount of lift the valve recieves.And I hardly see how it can change the length of time,or duration,that the valve is open.The only thing changeing gear postion is going to do is allow you to control when the valve is lifted.Nothing else.



Let me throw something the mix.
On small Briggs and Kolher engines used for pulling tractors and high speed go carts,folkes have learned that useing some heat from a torch and a vise,and a pair of channel locks on a cam shaft can help give 1 lobe or the other a slight twist 1 way or the other to change valve timeing of only 1 valve.
They also weld onto the cam lobe and then grind it to allow for more lift and time that the valve is lifted.
Would this help a T to twist the camshaft in certain areas to change valve timeing of only the exhaust or intake valves?

Personaly I think I will just leave mine as ol Henry made it because He has designed more engines than most of us and if he decided the gear is in a good place,I will take his word for it.But there aint a thing wrong with experimenting either.If Henry and others had not experimented,we would be argueing over which hay produces less "emissons" for us to scoop out of the stable.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck on Monday, January 28, 2008 - 10:43 am:

Mackster,

I used to race go-karts and that trick does work - retarding the intake timing to improve the high-speed power. But where we used it was on plastic camshaft Briggs 3.5 horse engines where the camshaft, lobes, and gear were nylon, molded over a steel shaft.

It might be a little tricky to pull that off on a T's camshaft, but what the heck would I know since I haven't done it even once, let alone a thousand times!

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom on Monday, January 28, 2008 - 11:29 am:

The original post was "I read on hear sometime back about advancing the cam gear like to have information how to do this and advantages.Can you buy a gear or do you have to redrill holes in gear thanks Ross".

My original responce was "I have had good luck with advancing the cam 1/2 tooth. There are 48 teeth on the cam gear and 7 1/2 degrees between each tooth. One half tooth is very easy to line up using a jig made from an old gear. The angular difference between the teeth for 1/2 tooth of advance is 3 3/4 degrees which will give you 7 1/2 degrees advance in valve timing. It helped a great deal with the low end torque of my touring which has a 3:1 ring and pinion and needed some assistance. I also did the same for a buddy of mine on his depot hack and the improvement was immediatly noticable."

The original poster wanted to know the advantages and how to accomplish it. I merely posted the experience I had with it. I did it because I have a reground cam that cam from the Northwestern portion of the states with a .290 lift and it was rumored to me that advancing the gear would help with low end torque. I communicated with the cam grinder who confirmed to me 1/2 tooth advance will help it and told me how to accomplish it. I then made a jig to drill the new holes in the correct position.

I have had good luck as on my car the RPM range for best torque is now lower and the car will pull a hill better than before. With stock valve timing and 3:1 gearing if I got behind a car that was pulling a hill at 23-24 MPH my RPM was well below his and I would have to use the Ruxtell everytime. Nobody is twisting anybodys arm to try anything. If this isn't something you want to try, then don't.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck on Monday, January 28, 2008 - 11:41 am:

Gary,

Your point is well taken, by me anyway. Unless you've done it many, many times and have dyno results to prove its effect, you might as well stop wasting your time by posting your results here.

Just my hypothetical opinion! LOL!

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky on Monday, January 28, 2008 - 03:34 pm:

Theoretical hypotheses is what got us to the Moon and back so there's nothing wrong with an educated prediction (design). I almost said "educated guess" but there's no guessing when the theory is a proven fact. Without theorems we'd still be counting with beads. Factual assumptions are the bases for proving any idea whether it's counting beads or building engines. Let's not discount a hypotheses as theoretical simply because you lack the knowledge to understand it.

Just my opinion and I'm sticking to it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe on Monday, January 28, 2008 - 11:39 pm:

Once it is a proven fact it is no longer a theory, it is a fact. There is a considerable difference between a random hypothesis and a hypothesis based on actual and factual knowledge which has then been tested in real world analysis. In my opinion -- and I'll stick to this based on my years of personal experience with people who actually do something and those who just talk about doing something -- I will put considerably more stock in the experience of someone who has developed his knowledge based on years of real world testing than someone who parrots what is stated in a book of theories, whether it is camshaft design or going to the moon. If every theory worked exactly as it is supposed to, and few do, there would be no testing aspect of development, all designs would be final at first completion of the design.

Incidentally, all hyphotheses, by definition, are theoretical. It is a redundant and ambiguous statement but one which is commonly used and understood.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Kopsky on Tuesday, January 29, 2008 - 12:15 am:


quote:

...knowing that they are based on actual experience as opposed to theoretical hypotheses.



That was your terminology, not mine. I know the definition of hypotheses.

By your qualification of meaningful dialog, engineers should be ignored and we should listen to experienced garbage collectors. Do as you wish but I'll stick with the math; theory or not.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Vitko on Tuesday, January 29, 2008 - 01:30 am:

The skunk works built some awesome stuff with the COMBINATION of good engineers and craftsman working together. I seriously doubt that the black bird would have came about without one or the other.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth Harbuck on Tuesday, January 29, 2008 - 10:11 am:

What we are all talking about here is an adjustment of a parameter that affects the way a four-stroke engine performs. We aren't talking about designing or redesigning anything. This same bickering could go on in another thread regarding where to set the mixture needle on the carburetor, the only reason it probably doesn't is that nobody has any reference point other than turns out on the mixture needle and not fuel flow. Or in another thread about where the spark lever needs to be. We're talking about teeth on gears here and some people want a "magic number" as to what is perfect.

What Paul Vitko considers perfect for his Z headed touring car with over and under auxiliary transmission under HIS driving conditions is not going to be the same as the guy running his "stock enough to be legal" roadster in the Montana 500.

Develop nothing. Cut a few gears and try it out for yourself and find the one that best suits you. And whatever you do, don't even begin to think that there is some "magic sweet spot" of some extra 10% somewhere between two of those gears. There is not.

Since I haven't done it on any engine that produces maximum power at a snail's pace, I stated that I would take baby steps. I know EXACTLY what effect valve timing has on ANY four-stroke engine - because I know WHY. I do not know the SLOPE of that effect - so I'd take baby steps.

Why all the bitching because I understand without having done it? Did I tell anyone what the magic number was or that there even is a magic number?

Stop looking down your nose at engineers. You can thank them and all those that worked with them for the easy life that you enjoy and take for granted.

Seth


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Tuesday, January 29, 2008 - 10:54 am:

Engineer In Training:

An Indian walks into a cafe with a shotgun in one hand and a bucket of bull manure in the other. He says to the waiter: "Me want coffee."

The waiter says: "Sure chief, coming right up." He gets the Indian a tall mug of coffee and the Indian drinks it down in one gulp, picks up the bucket, throws the manure into the air and blasts it with the shotgun, then he walks out.

Four days later the Indian returns. He has his shotgun in one hand and another bucket of manure in the other. He walks up to the counter and says to the waiter: "Me want coffee."

The waiter says: "Whoa, Tonto, we're still cleaning up from the last time you were in here. What was that all about, anyway?"

The Indian says, "Me in training for job as Aerospace Engineer: drink coffee, shoot the bull, and disappear for a few days.

rdr
Aerospace Engineer (ret)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Tuesday, January 29, 2008 - 11:22 am:

Yeh, that one has been around since the Mercury program or before, complete with the terminology of the day. Sorry if it offended. I just ran across it in my files, and the first thing I thought when I read the first line was a guy from India. But I digress.

What I take away from this whole thread is that Henry set the cam timing as the best compromise for the entire variety of cars and trucks built. Did it ever change during the entire production run? Nobody has said so.

Adjusting the cam to get more low end torque is a zero sum game. Horsepower, which accelerates you up to cruise speed, is torque times RPM.

Are you prudent to advance the timing to get more torque at low end for your heavy sedan or hack? Henry addressed that by offering the 10 tooth pinion as an option in later years.

This discussion would hardly exist if the T had a second gear. There is just too wide a gap between the 2.75:1 low and 1:1 direct. Sliding gear trannies of the era typically had 3:1, 2:1 and 1:1 gearing. The lack of a second gear is what made aux trannies so popular over all these years.

Every aux tranny is cumbersome to use in concert with the T tranny. In some cases, you need three hands, or even a foot feed. Mostly, they do a poor job of filling the gap between Ford low and direct.

It's really too bad Henry didn't come up with a three speed planetary. The Model A and later cars would never have had sliding gear trannies, and maybe Ford would have been first with an automatic.

Brits have reported on this or the other Forum that a few English cars did have 3-speed planetaries.

rdr


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tim ( www.ModelTengine.com ) on Tuesday, January 29, 2008 - 01:05 pm:

The original question was "I read on hear sometime back about advancing the cam gear like to have information how to do this and advantages. Can you buy a gear or do you have to redrill holes in gear thanks Ross"

It looks like Ross is no longer with us? I hope he got his answer before all the bickering started. Ross, the answer is "yes".

I believe a few of us answered his question and added more information than was expected, before it became the usual show of emotions.

The heated topics, timing theory and gear material:

I offer nylon gears with one or two sets of holes, as a side line to our engine rebuilding service. Dan offers Bronze. We each feel our own choice of material is the best way to go.

Both us us do this for a living and both of us are very good at what we do - which proves that sometimes there are two or more correct answers for the same question.

I build "high performance", top of the line, blueprinted, balanced, mildly ported, complete T power plants here. We check the gears in the motor with a degree wheel before final assembly - every motor, even stock timing. So far we've have found several gears that were not drilled and marked properly. Some were problems with the small gear and some were the large gear. The worst so far was 13 degrees retarded. If we had not found that little mistake, I doubt that the engine would have run at all. We here feel it's best to check the little details and avoid costly mistakes that create unhappy customers.

Dan sells both gears as a set and has a reputation for getting them right. I have used his gears (bought in pairs) as well, and no problems were found. I believe he also rebuilds engines.

On my website ( www.ModelTengine.com ) you will see the nylon gears for sale under "products". These are aircraft grade nylon, and I've been using them since 2005. To the best of my knowledge, none of them have swelled up, melted, shed any teeth, or worn out early. Unlike the bronze, aluminum, or steel gears, these nylon gears are SILENT.

I can provide these large gears with whatever advance or retard your little heart desires. I don't sell the small gear, so some faith is required if you go this route. I recommend 7.5 degree advance.

The one that didn't work out: I went wild and put one in my own car with 8.5 degrees advance a few months ago. My own car has been the only failure. I believe this is due to a worn engine, with 1/8" slop in the front cam bearing and a camshaft that is worn down to the nub, and the vaporizer intake. Or maybe my crank gear is off, no way to tell with the engine in the car. There was no noticeable difference with the gear swap. No decrease in performance, but no increase either. This "failure" still runs and drives just like it used to.

Although I have worked as an engineer for many years in an unrelated field, and I have been playing with and around T's for almost 40 years, I don't know about the angle of the lobe vs. the alignment of the valve geometry when the moon is full nor do I try to tell anyone why moving valve openings to the X variation of the BDC makes it work. It's irrelevant. The fact is that it works if you do it right, and unless your designing a new custom camshaft, who cares why?

I do feel (by the seat of my pants experience) that it moves the "power band" to a different rpm range, and if you bring it to a lower rpm range, it make the car more fun to drive.

In my humble opinion, a stock T's "breathing" is so restricted that it can't reach it's true potential. By that I mean that the stock cam grind would work better in an engine that turns up in the 3000 rpm range, sucking though two little 1" holes won't allow the engine spin that fast and the bearings won't survive anyway. Advancing the cam only moves that potential power into a range that the T engine can actually use.

A couple of very learned T people told me about this "trick", one would probably give Einstein a run for his money with theories and logarithms, the other came to the fact that it works by trial and error. I spent hours on the phone with each of them independently as they explained how they came to know that this works. One used a dyno for the results and the other routinely wins long distance races with an average speed in excess of 55 MPH in a bone stock T. Neither knew at the time that I talked to the other and they both told me the same thing - 7.5 degrees advanced = more usable power. I am grateful to both of them for taking time out of their busy lives to share this knowledge with me.

Bottom line, do what you want with your car. It's yours and no one else's. If you don't want to try this, then put it in the old fashioned way - dot to dot, trusting that the gear manufacturers got it right. It's been working fairly well for 100 years now.

If you want to modify a large gear (nylon, fiber, bronze, aluminum, steel, whatever you like best) and need advice on how, give me a call or email and I'll tell you the easiest way to do it - it takes less than five minutes.

If you prefer to try this the "right way", and have an entire "balanced and blueprinted" power plant that involved no guesswork, blind faith, or theories built for you, we're here for you as well.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson on Tuesday, January 29, 2008 - 07:52 pm:

Hi all
I am happy to see Steve Coniff posted some of his extensive knowledge on this subject. Steve is a friend and can tell you every word he speaks comes from actually creating many experimental Model T camshafts and testing them in Model T cars. Steve is way beyond simply moving the cam/crankshaft gear relationship around and give it a try stage. He is into changing the shape of camshaft lobes to provide optimal Model T engine performance.
Pay close attention to everything Steve says.
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By Fred Houston, Broken Arrow, OK on Tuesday, January 29, 2008 - 08:53 pm:

Me thinks Patterson wants a free ride up the mountain.


Top of pagePrevious messageNext messageBottom of page Link to this message  By jack daron-Indy. on Tuesday, January 29, 2008 - 09:23 pm:

Do you think?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ron Patterson on Tuesday, January 29, 2008 - 11:14 pm:

Fred & Jack
I can get ride with Steve anywhere I like.
See you in Seattle in 2009
Ron the Coilman


Top of pagePrevious messageNext messageBottom of page Link to this message  By jack daron-Indy. on Tuesday, January 29, 2008 - 11:28 pm:

You have away to much money.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom on Wednesday, January 30, 2008 - 08:58 am:

My final post on the subject. I for one am appreciative for the experimental nature of many Americans. This country won WWII because of it. The reason we broke through the hedge rows in France was because we had smart kids right off the farm weld up some angle iron to the front of our tanks and cut through it. They understood it didn't have to be perfect, optimal, or a work of art. It merely had to last for the 5-10 minutes it would take to cut through. Our opponents took great pride in their engineering efforts of everything they did and the superior level of quality they produced. They were not able to adapt, react, and accomplish like we were (because of course they knew better).

The Wright brothers were not aerospace engineers either, yet they accomplished what others stated wasn't possible (I believe it was the experts by the way that were the naysayers). This also make me wonder what the heck was Sir Frank Whittle thinking with this jet propulsion thing, or Sanford Moss with the turbo charger. Trial and error (aka testing based on probable known outcome) is still a valid way of accomplishing results. The theory being understood and the testing is proof of concept. I beleive that is how the polio vaccine finally came to be.

Again, I posted my experiece with my car and a buddies depot hack. We were both please by the increase in low end torque and choose not to do further testing. If 11 degrees advance is optimum, then somebody will figure it out one day through trial and error.


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