Valve Guide Material Comparison

[cjburr]

I have been told that manganese/bronze valve guides are a better alternative than cast iron guides for street use.

I would appreciate anyones opinion as to the pros and cons of both materials.

Thought this would have been a subject talked about before and did a search, but didn't find my answer in the first 10 pages or so.

If this subject has been rehashed many times, a link to the threads would be appreciated.

Chris

[Pete]

Hi Chris , and Welcome to the place. Enjoy your stay.

There is a thread in this section on Valve guide materials which may provide a starting point for you.

Have a look on Google as well.

Cheers , Pete.

[cjburr]

thanks Pete, saw that one but it didn't have the info I was looking for.

I'll try more google.

[Sir Yun]

I would think that the use of manganese bronze for guides has a lot to do with the use of the material of the valve. A cast iron guide used in conjuction with a chrome stemmed valve is a common combination used by OEM's ( by definition excelently suited to high mileage use).

an raw uncoated stainless valve wil gall in a cast iron guide so you have to use bronze

there are a few types of bronze ( or maybe one should say yellowish coloured material) that have been used for guides. ranging from PB1/navy bronze that is very soft (and thus wears quickly) to something like Colisbro (copper-nickel-silicon ),Trojan or Copper-cobalt-beryllium (which has serious health warnings).

[panic]

Ampco 45 = good.

[cjburr]

I found this while googling

Myth: Bronze guides don’t last.

Fact: Early silicon based bronze alloys used in valve guide applications quickly earned the reputation of having poor wear performance. It wasn’t until high nickel based bronze alloys (AMPCO 45) were introduced that the valve guide market was able to offer a superior bronze valve guide, suitable for high heat applications (Nitro-methane etc…).

But still, people realised that that material was not lasting as long as cast iron. One of the main reasons is because this material needs to be fit at a looser clearance to prevent seizing problems.

After extensive research, the majority of automotive and motorcycle racing head manufacturers and rebuilders are now installing manganese bronze alloy guides. The two principal advantages of this alloy is superior heat transfer and also that the engine builder is able to fit the guides at a tighter clearance for a better oil film control and longer life. We should call this alloy ‘’zinc bronze alloy’’ instead of manganese bronze because it contains nearly 30% zinc, 2-3% manganese. Manganese is the hard part of the recipe and the zinc is the bearing ingredient, a material which is also a self lubricant.

Myth: Why use manganese bronze alloy when I know that a stock Evo or Twin Cam guide can last 60,000 miles or more?

Fact: It’s true that for stock replacement, cast iron guides work fine. However, the problem starts with the high performance applications. In high lift applications, the guides need to be shortened. With more heat and side load from the valve involved, the oil film between valve and guide deteriorates more quickly. In addition to increased viscosity breakdown, cast iron guides are also an abrasive material which induces the premature wear that we’re used to see with this application. In cases where valves have collided with each other or with the piston, cast iron guides have been found to fracture and deposit damaging fragments into the cylinder and combustion chamber. This is not the case with manganese bronze guides.

Here they talk about premature wear but it seems that if OEM's are using cast iron and chrome stem valves for longevity that combo should be fine in most applications unless you're going the high performance route.

Chris

[SWR]

But still, people realised that that material was not lasting as long as cast iron. One of the main reasons is because this material needs to be fit at a looser clearance to prevent seizing problems.

I think that's the myth...that you have to have them really loose with Trojan or A-45. I always make them even tighter with bronze guides than cast iron ones...and,maybe I'm just lucky,but I never had a seize problem doing this...

[bobqzzi]

But still, people realised that that material was not lasting as long as cast iron. One of the main reasons is because this material needs to be fit at a looser clearance to prevent seizing problems.

I think that's the myth...that you have to have them really loose with Trojan or A-45. I always make them even tighter with bronze guides than cast iron ones...and,maybe I'm just lucky,but I never had a seize problem doing this...

Bjorn,

How tight do you go on high output turbo cars?

[SWR]

Bjorn,

How tight do you go on high output turbo cars?

Unless their main goal is going dragracing,where they risk not getting the whole thing up to temp evenly before flooring it,I do about one - one and a half thou,sometimes less...depends a bit on stem dia and material. And projected use,of course.

[cjburr]

But still, people realised that that material was not lasting as long as cast iron. One of the main reasons is because this material needs to be fit at a looser clearance to prevent seizing problems.

I think that's the myth...that you have to have them really loose with Trojan or A-45. I always make them even tighter with bronze guides than cast iron ones...and,maybe I'm just lucky,but I never had a seize problem doing this...

that statement was about the silicon/bronze guides that came out long ago.
I believe the Trojan and A-45 are manganese/bronze and can be fitted to much tighter specs than their predecessors.

[SWR]

I believe the Trojan and A-45 are manganese/bronze and can be fitted to much tighter specs than their predecessors.

Trojan is copper-nickel-silicon from what I know..

[GregGood]

I found this while googling


Myth: Why use manganese bronze alloy when I know that a stock Evo or Twin Cam guide can last 60,000 miles or more?

Fact: It’s true that for stock replacement, cast iron guides work fine. However, the problem starts with the high performance applications. In high lift applications, the guides need to be shortened. With more heat and side load from the valve involved, the oil film between valve and guide deteriorates more quickly. In addition to increased viscosity breakdown, cast iron guides are also an abrasive material which induces the premature wear that we’re used to see with this application. In cases where valves have collided with each other or with the piston, cast iron guides have been found to fracture and deposit damaging fragments into the cylinder and combustion chamber. This is not the case with manganese bronze guides.

Here they talk about premature wear but it seems that if OEM's are using cast iron and chrome stem valves for longevity that combo should be fine in most applications unless you're going the high performance route.

Chris

The type of cast iron used by Harley is very hard and non-typical of what the automotive aftermarket uses, so essentially there's no comparison between them and automotive cast guides. I have no issue with using factory Harley guides. The main drawback to them is as stated above, that they are brittle and if you bend a valve bad enough, pieces will break off and get into the cylinder. A bronze guide will just bend along with the valve.


I like manganese bronze for most apps, but when running titanium valves I prefer phosphorous bronze, aka "copper bronze" because it is easy on valve stems and is a "sacrificial bronze". I'd rather wear out a $200 set of guides than a $1500 set of Ti valves. Also, the phosphorous bronze performs better on the exhaust side of high heat apps like turbo. Manganese guides that are exposed into the exhaust port can split and break away.

[cjburr]

thanks all for your wisdom on this subject, the motor I'm currently running is an 06 Sportster with 1250 kit, stage3 heads, 11 to 1 compression, 30 degree squish/matching pistons, and nicasil Axtell cylinders.

the shop that did my heads neglected to seat the seals on the guides and over reamed the guides to .005, when I had another shop fix the heads they installed cast iron guides with the proper clearances.

I believe the iron guides will serve me well and will post if I have any issues with them.

[MOPAR MAN]

Wow for a new guy to this kinda thing making a decision when there really seems to be no right answer is difficult. lol I am planning on using Ferrea ti intakes and Super alloy exhausts for a supercharged application... what would you guy's recommend I use?