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Old 06-16-2004, 09:41 AM
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Automotive Myths Debunked- Add Your Knowledge!

Hey Rodders, I figured it would be good in the Intro forum to write a thread compiling as much knowledge as we could about the myths of hotrodding, and things people are commonly confused about. If this thread takes off I think it could be a useful read for beginners, if not, oh well I tried!

Here are a few I thought of:

Aside from popular belief, roller cams do not make most of their power from friction losses regained, the ramps of roller cams are more aggressive due to the angle of attack available on the roller of the lifter.

Too much carb does not always make your ride faster, a lower intake velocity can actually hurt throttle response and low end power.

Most Roller tip rockers do not roll at all- most of them don't even have a bearing in the roller tip! So when the pressure of the spring is put into the "roller" the coefficient of friction is so great, that the tip simply slides across the valve without rolling, just like a stamped rocker that costs 30-50 dollars less for a set!

Yes you can put 305 heads on a 350, no they don't flow enough to make it worthwhile, and the port job will cost you 600 dollars if you don't know how ot do it yourself. Wives tale- not a good idea.

Assuming you have the octane to run the compression: if you make two heads, one out of iron, one out of aluminum and otherwise these two heads are exactly the same, the iron head will make more power. Why? Because Aluminum acts as a heat-sink and moves heat away from the combustion chamber. Heat is what makes the explosion more violent (and more powerful). The goal of boosting compression is boosting the amount of heat generated in the combustion chamber. Given the heat-sinking properties of aluminum, roughly 1 point of compression is "lost." Therefore, when one runs aluminum heads, the compression must be boosted approximately 1 point to compensate. Many believe that you "can" run an extra point of compression with aluminum heads- rather: you "must" run an extra point, or risk falling out of the compression range you desired originally!

Aluminum intakes do not make your ride run any cooler. In fact, just like above, iron and aluminum flow exactly the same. Aluminum is known as a performance product due to its weight saving properties, therefore an aluminum manifold only does one thing: saves weight (well that and there aren't any similar iron manifolds!). As a matter of fact, an engine reaches its operating temperature and more or less stays there the entire time its running. The heat of an engine actually rises after its shut off because the heat is no longer being dissipated by the cooling system. On average, an engine will get 20 or more degrees hotter after it is shut down.

Crankshafts will not bend by laying them on the floor- wives tale.

Batteries do not lose their charge if you don't put a piece of wood on them or get them off the ground- wives tale.


Anybody else got some? I think this is useful stuff!

K

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Old 06-16-2004, 05:18 PM
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wow i thought that the battery thing was true just thismorning i put mine on a 2x4 to charge on instead of being on the ground
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Old 06-16-2004, 10:23 PM
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Rubber cased tar top batteries from the past would lose their charge. Modern batteries with a plastic case will not.

Do not act cool and say you added Nitromethane to your tank. I doubt you know where to find it and the long burn rate actually make you lose power in an engine designed to burn gas!
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Old 06-17-2004, 08:13 PM
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I'd argue the bit about roller tipped rockers. Mine show an even wear pattern all the way around the roller--evidence that it spins. I would guess that with the solid cam I am using, the roller has a chance to spin ever so slightly as the valve tip makes and breaks contact with the roller, perhaps in a ratcheting manner.

tom
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Old 06-17-2004, 08:40 PM
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Quote:
Originally posted by machine shop tom
I'd argue the bit about roller tipped rockers. Mine show an even wear pattern all the way around the roller--evidence that it spins. I would guess that with the solid cam I am using, the roller has a chance to spin ever so slightly as the valve tip makes and breaks contact with the roller, perhaps in a ratcheting manner.

tom
Yeah, one of my roller tips has a flat spot that I just let ride on the flat spot. So I know the others have to be spinning. I call it "ol'Blue", because it appears to have gotten quite a bit hotter than the others when they were on the previous owners low buck race engine.

Explosions aren't supposed to happen in the combustion chamber, that's detonation. What's desired is a controlled burn.

Over sixty percent of an engines heat is dissipated through convection. Therefore aluminum would be beneficial to aid in the cooling process due to it's capability to conduct heat better.

Every shop manual I've ever read as well as my text books say to stand a crank on end when storing.
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Old 06-17-2004, 08:50 PM
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Well my point about the rockers is that even if they do move a little, if they don't have a bearing what's the point? Either the non-bearing stamped rocker slides on the valve, or the non-bearing "roller" tip rocker slides on the inside of the flat metal of the roller with no bearing, then on the valve. There aren't friction losses gained there!

You could make an engine out of aluminum and another out of iron and they'd run at the same temprature regardless of convection. The engine is constantly creating more heat that either aluminum or iron can dissipate through convection, that's why we have radiators and thermostats. THe only difference is the engine made of aluminum would probably cool off faster after the car is off.

There's never been a case of a crank that's warped on its side. There used to be a myth that if you used your cell phone at a gas pump that the gas could expode too. Some gas stations even put it on the gas pumps! ONe of my friends was made to actually hang up on me a few years ago because he was talking on the cell while filling the tank. THis myth has also been debunked.

Ok well, maybe this thread isn't going to work. Too much of this hobby is based on advertisments (which in the united states do not have to be truthful) and hearsay.

Gotta love it though-

K
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Old 06-17-2004, 09:06 PM
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one of my favorites is that people seem to have to mention that there engine is bored out...or gonna get it bored out. like its a big power maker.
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Old 06-17-2004, 09:26 PM
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I have to dispell a myth about Pontiacs... Certain persons of ethnicity do not actually mistake them for Cadillacs.

Either Killer is going to think that was funny, or he is going to carry on about how that wasn't very politically correct. Bets? Anyone?
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Old 06-17-2004, 10:08 PM
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Quote:
Originally posted by killerformula
Well my point about the rockers is that even if they do move a little, if they don't have a bearing what's the point? Either the non-bearing stamped rocker slides on the valve, or the non-bearing "roller" tip rocker slides on the inside of the flat metal of the roller with no bearing, then on the valve. There aren't friction losses gained there!

You could make an engine out of aluminum and another out of iron and they'd run at the same temprature regardless of convection. The engine is constantly creating more heat that either aluminum or iron can dissipate through convection, that's why we have radiators and thermostats. THe only difference is the engine made of aluminum would probably cool off faster after the car is off.

There's never been a case of a crank that's warped on its side. There used to be a myth that if you used your cell phone at a gas pump that the gas could expode too. Some gas stations even put it on the gas pumps! ONe of my friends was made to actually hang up on me a few years ago because he was talking on the cell while filling the tank. THis myth has also been debunked.

Ok well, maybe this thread isn't going to work. Too much of this hobby is based on advertisments (which in the united states do not have to be truthful) and hearsay.

Gotta love it though-

K
Roller tips do roll, end of story. Whether or not they free up horsepower, or reduce friction is beside the point of your original statement that "most roller tips don't roll". And besides that, due to the fact that they roll, guide wear is gonna be reduced at the least.

The motors would in fact run at the same temps whether it's made from aluminum or cast iron. That's by design to maintain operating temperature, not the properties of the materials they're made with. You even admitted to the fact that the aluminum engine would cool down faster after shutdown. That's because the rate of convection is greater with aluminum. What that means is that the aluminum would be able to dissipate more heat (by convection) if the demand on the cooling system were at the limits of it's capabilities. A most desirable trait for high performance use.

I would like to know where you learned of there never being a case of a crank being warped from laying on it's side.

I'm sorry you bought a "Ding King" and feel deceived by their advertising because it wouldn't pull your whole quarter panel back into shape. "Too much of YOUR perception of this hobby is based on advertisements", is what you should have said. Most of us live it, day in and day out.

You really have no idea what you're talking about do you?
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Old 06-17-2004, 10:21 PM
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hey best, post a pic of a crank that's warped by laying on its side, if there are so many...

Why are you so personally offended by my comments? No roller tips don't roll. They might move a little, but they most certainly don't "roll" like they are advertised to. 90% of those boxes say "Free up Horsepower!!!!" I think its crap that they deceive people with no real proof.

You know best, for all your griping and making fun of me and my projects, lets see a pic of you or some of your projects or your hotrod! Do you even have one? Seriously man, lighten up.

The material your motor is made of does not add into its capacity to cool. After your motor is at its operating temp the capacity of the convection cooling is gone. If it were true that an all aluminum motor cooled better (say a certain percentage) than an all iron motor, you could build two identically, put a high-performance cooling system on the iron one, and since the aluminum one is made of all aluminum, you wouldn't need all that fancy radiator and pump, because everything is aluminum, right? Well?

As far as your comment Luc, WTF have I ever said to you man? I've been nothing but cool with you since day one, thanks for the comment.

K
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Old 06-17-2004, 10:36 PM
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I didn't know I said anything that should be offensive to you.

What I was alluding to was the fact that you have been overreacting to peoples posts a little lately. I mean don't get me wrong, I can give some snappy answers to stupid questions, but you gotta get back to good humor every once in a while.

Anyway, if you haven't heard the funny PONTIAC acronym before, I guess my joke wouldn't have made much sense to you. Have one of your local rednecks explain it to you.
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Old 06-17-2004, 10:40 PM
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You're trying to present facts as "wives tales" without even having a clue as to what you're saying. I'm not personally offended by your comments I'm trying to keep you from spreading even more myths/ignorance.

You should stick to subjects like "How to live with homos", or "How to be politically correct to the point of pointlessness".

You really haven't a clue as to what you speak about with such authority do you? For being an educated person, you really have no common sense do you?
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Old 06-17-2004, 10:51 PM
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Hey genius, you still haven't presented any reasonable evidence for your claims either.

BTW, where did you say the pic of your hotrod was? Just checkin. Given that its pretty obvious you don't even own one, and I've worked hard on mine, what gives you the authority and makes you judge and jury on my comments?

Why are you bringing up again that one of the guys in my house is gay again? ***** dude, you bring it up and think about it more than I do!!! Who's got the problem with it again? ha ha ha... that's pretty funny.

I've been building motors since I was a kid man, that's what gives me the authority to make comments on this board. And unlike you, I've been known to admit when I'm wrong. Honestly man, you prove it, I'll swallow my words. That's what this thread was supposed to be about. BTW, its important to know that cranks don't warp when you lay them on their side, because its a much safer way to store them! WHy stand them up if they don't absolutely need it, you risk them falling!

Give it a rest man, I don't understand what you're so insecure about. NOtice that you're the one who decided to make this personal, not me. Congratulations, you don't act your age. Give me some time, I'll figure out your prize.

K
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Old 06-17-2004, 11:16 PM
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I'm talking about automotive 101 here moron.

You've been building motors since you were a kid.......that's why you can't replace brake shoes? That's why you throw money/parts at your Jeep when it doesn't run, instead of doing simple troubleshooting and resistance/voltage checks on various sensors/components?

Let me draw you a picture.....

Yes the capacity for convection is for the most part gone when the motor is at operating temps. However the cooling system in the aluminum engine is not having to work as hard to keep up with demand due to the convection rate of the aluminum being more efficient. Thus the TOTAL cooling capacity is increased with aluminum.

I took my photos out of my album a while back because I was leaving and fed up with dip*****s like you on here. Don't worry, I'll be sure to put them back in as soon as possible.

You wouldn't make a pimple on a mechanic's *****.
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Old 06-18-2004, 12:32 AM
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ennough with the ****ing arguments, this is turning into a skateboarding topic. whine whine whine ***** ***** *****........
lets carry on cause this is interesting reading.
i would add some but i cant think of any.


CHEVYS R BETTER THAN FORDS FOR THE MONEY YOU SPEND

NO ARGUMENTS

NO REPLACEMENT FOR DISPLACEMENT
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