Another "bushing"material question

[tderonne]

Ok nerds.

Another bushing material type question.

Valve guides. Material is free. I've often heard people say that means they can trim the portion of the guide that protrudes into the intake and exhaust runners, air being the alternate material.

So. Is it? Or has the design of the guide been altered?

Would a poll of who's done it help? I haven't.

[joeg]

A "shortened" guide is made of various materials, including air.

Peace.

[Bill Miller]

Sticky question Tim. Material is free, but is design? Can they be multi-component? (e.g. bronze and air)

[Andy Bettencourt]

Is it too early to start :birra: ?


AB

[Joe Harlan]

Is it too early to start :birra: ?
AB
[/b]


Well it's not an answer but I use replacements of OE design or bronze guideliners just to be sure they will pass inspection.

[bldn10]

My engine doesn't have valves so I may be missing something technical but let me ask this - if you were writing the rule and you wanted to allow design modifications to the valve guides, would you settle on "Valve guide material is unrestricted?" Or would you say "Valve guides are unrestricted?" Although the rules are not always logical, there is a presumption that they mean what they say. Hey, is a valve guide like a bushing - a sleeve or tubular insert? :wacko:

[Greg Amy]

I wish I had the motivation to compare individuals' answers on this question to their position on the suspension bushings/spherical bearings contre-temps. Methinks there may be conflict there...

Me? I aint' steppin' in this pile, but I do have my "beating a dead horse" emoticon at the ready... - GA

[tderonne]

Hmmm, thought this would be a pretty clear cut way to look at the whole material vs. design issue. Perhaps it's too clear cut?

I'd even listen to the argument that a shorter guide is still the same design, since it still performs the required function.

Maybe folks doing it, know what it's worth and are shutting up?

[Rabbit07]

Tim,


You know I am a fan of air for bushings.

Chris

[bldn10]

"I'd even listen to the argument that a shorter guide is still the same design, since it still performs the required function."

Performance of the intended function may be relevant to help explain how an ambiguous rule should be applied to a particular part but it is not one and the same, and that notion needs to be wiped out once and for all. I.e. it is simply not correct to say that an OEM "design" has not changed simply because the part still performs the OEM function. On the other hand, if it does not still perform that function, it ceases to be the same part and is illegal unless otherwise specifically allowed. Likewise, performance of an additional function may render it illegal even if it also still performs the legal function. If the rule is unambiguous on its face, "the argument that a shorter guide is still the same design, since it still performs the required function," does not even come into play.

I assume that shortening the guide cleans up flow in the head? I don't see where that is an allowed function of a valve guide. But it makes no difference anyway because you can only change the "material" and air, although a clever suggestion, is not "material" w/i the meaning of the rule. Although I don't think it is necessary to take it this far, you could also say that the rule only allows a complete material change and that, if air is a material, you cannot use guides made of 2 or more materials.

[Ron Earp]

Hey, is a valve guide like a bushing - a sleeve or tubular insert? :wacko:
[/b]

Ooooo, a valve guide is precisely like a bushing! :dead_horse:

[jake7140]

So I could shorten my upper control arms (on say an old gm car) to get more neg camber??? No.

[RSTPerformance]

For Real??? :119: this is something that people do? or find acceptable???

I think you will have to work real hard to prove that the Air is your alternate material, especially where it is not consealed in a certain area to perform the function of an alternate material...

Raymond "I will let the rules nerds get out the GCR, and in my mind I will make my ruling!!!" Blethen


PS: It is very interesting sometimes to read these crazy ideas, and think about how I would look at them when stewarding... so in fact debate away :014: ... I am off :eclipsee_steering: to do as Andy has... :023: cheers :birra:

[tderonne]

So how about this. I have a head rebuilt including installing new valve guides. The removed guides, factory ones, were 2" long. The replacement ones are 1.75". Checking the service manual, there is no guide dimension listed. Is the 1.75" guide a legal replacement?

[Gary L]

To quote someone in a nearby thread....

"Things are legal or thay are not."

Oops! Was that you? :D

No... 1.75" long valve guides are not legal replacements for 2.00" long valve guides. That same service manual probably doesn't give you the weight of the crankshaft, either. That doesn't mean you can replace the stock crank with one that weighs 10 pounds less.

[tderonne]

I can present the other side's argument every once in a while, right?

Mine are bone stock. Some of the folks on the track with me aren't.

[zracre]

No... 1.75" long valve guides are not legal replacements for 2.00" long valve guides. That same service manual probably doesn't give you the weight of the crankshaft, either. That doesn't mean you can replace the stock crank with one that weighs 10 pounds less.
[/quote]

My interp is if valve guide materials are open, then they are free to be made out of jello if it works...you can't replace the crank with a 10# unit anyways...that is specifically outlined. Lets say someone came up with a liquid compound that hardens to replace valve guides (highly unlikely) it would still be legal regardless of its size. If it says it may be replaced with a stock replacement alternative, then you have a problem...

[Gary L]

I can present the other side's argument every once in a while, right?
[/b]
No prollum... go for it.


Mine are bone stock. Some of the folks on the track with me aren't. [/b]
If I know this to be the case, "some of the folks on the track" are about to be protested.

[Gary L]

My interp is if valve guide materials are open, then they are free to be made out of jello if it works...you can't replace the crank with a 10# unit anyways...that is specifically outlined. Lets say someone came up with a liquid compound that hardens to replace valve guides (highly unlikely) it would still be legal regardless of its size. If it says it may be replaced with a stock replacement alternative, then you have a problem...
[/b]

I repeat... "some of the folks on the track" are about to be protested. I have no problem whatsoever with valve guides made of jello, silly putty, or carbon fiber reinforced unobtainium. But in this case, they damned well better be 2.0 inches long. Same old argument, really; it is very specifically the material that is allowed to be changed, not the dimensions. ITCS page one... if it doesn't say "yes", it means "no".

[Andy Bettencourt]

I have no problem whatsoever with valve guides made of jello, silly putty, or carbon fiber reinforced unobtainium. But in this case, they damned well better be 2.0 inches long. Same old argument, really; it is very specifically the material that is allowed to be changed, not the dimensions. ITCS page one... if it doesn't say "yes", it means "no".
[/b]

Yup.