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Phosphor Bronze Valve Guides?
#800519 03/09/20 7:52 pm
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Hello,

I have a quick question.I have been browsing for valve guides and came across (steadfastcycles) valve guide set that is made of a Phosphor Bronze.

Here are their claims:

"These guides are Phosphor Bronze which is the best material to use for guides on these Classic Bikes. Silicon Bronze which is the next grade up tends to wear out the valve neck so we stay away from it. With these bikes the Phosphor Bronze offers better lubrication and they live better in the aluminum heads." There are many opinions on this subject but this is our information after 30 years of testing in many different environments, and conditions. Our tolerance on these guides is tighter and more accurate than many of the other leading suppliers, (the hole is closest to center than any other guide available)."

Does anybody have any opinions or experience with these

Thanks

Last edited by Jaybird79; 03/09/20 7:55 pm.
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Re: Phosphor Bronze Valve Guides?
Jaybird79 #800521 03/09/20 7:56 pm
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They don’t last very long in a road going Triumph twin.

I get much better service from cast iron guides. The modern aluminium bronze guides may be better still: I don’t know.


Amateur Loctite enthusiast.
Re: Phosphor Bronze Valve Guides?
Jaybird79 #800530 03/09/20 8:54 pm
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There are many different materials available for guides these days, as well as valve (stems) themselves. Which works best with what is worthy of a PhD thesis.
Other considerations such as lubrication (or not) and rocker geometry/condition of rocker to valve tip surface would need to be factored in.

Another factor is that bronze expands with temperature closer to that of alloy, reducing the possibility of the guide becoming loose in the head. This is a major pain when it happens.
An iron guide in an alloy head should have a tighter interference fit than a bronze guide requires.

I didn't see which particular engine being discussed, but if it happens to be a 650/750 with alloy head, I've exclusively used bronze guides for decades.
The only time I experienced rapid guide wear was when I used some valves which I can only describe as made of crap. The tips of the valves developed deep depressions at the contact areas with the rocker pins. It's easy to appreciate how this would exert excessive fore/aft force on the valve tips.
That isn't usually so extreme a problem, and there are different adjuster tips available (though I've not used them).

Just thoughts.

Re: Phosphor Bronze Valve Guides?
Jaybird79 #800546 03/09/20 10:43 pm
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Problem is with good aluminium or silicon aluminium bronze guides, finish honing has to be done rather than reaming.
Most blokes don't have a guide hone in their tool kit but will have a guide reamer. This rules out doing a diy guide job using
PM or the latest MAP guides, either of which are excellent material. Some guys swear to having guides lined, but not
having any experience with that or knowing what material they use i can't comment, other than the fact the original guides
must be very trusted in the head before considering this option. The use of better materials does allow closer fits for the valves
as well as giving better heat transfer and longevity, whether any of these matter to you is about what the bike is used for.

Re: Phosphor Bronze Valve Guides?
Jaybird79 #800549 03/09/20 11:03 pm
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https://www.fagengine.com/pages/cylinder-head-rebuilding
He also sells the parts and is in N Hollywood if that is close to you. It's worth the trip just to see the shop.


1968 T120R
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Any advice given is without a warranty expressed or implied.
Re: Phosphor Bronze Valve Guides?
Jaybird79 #800575 03/10/20 2:33 am
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Thanks for the reply's.For those wondering I have a unit 500.The bike is a regular street bike.I do have new stock cast guides and valves but was thinking about using bronze instead. I know many say KPMI is the best you can get but seen these for sale and wanted to see if there was any input on them.

Re: Phosphor Bronze Valve Guides?
triton thrasher #800579 03/10/20 3:38 am
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Originally Posted by triton thrasher
I get much better service from cast iron guides.
I only ever tried one set of cast guides - everyone warned me that they will grab a valve - and they were right. I went back to bronze as soon as I got home. I admit I was on a long ride [10 hours+], on a hot day, loaded up with tent, swag, saddlebags etc, and doing a consistent 120-130km/h, not sure if this contributed?
Never had it happen with bronze.

Re: Phosphor Bronze Valve Guides?
tridentt150v #800593 03/10/20 6:36 am
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Originally Posted by tridentt150v
Originally Posted by triton thrasher
I get much better service from cast iron guides.
I only ever tried one set of cast guides - everyone warned me that they will grab a valve - and they were right. I went back to bronze as soon as I got home. I admit I was on a long ride [10 hours+], on a hot day, loaded up with tent, swag, saddlebags etc, and doing a consistent 120-130km/h, not sure if this contributed?
Never had it happen with bronze.

There’s a correct clearance for any of the combinations of valve and guide materials. Too tight and it sticks.


Amateur Loctite enthusiast.
Re: Phosphor Bronze Valve Guides?
Jaybird79 #800598 03/10/20 7:06 am
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When I did the head on my Trident I got those guides from Steadfast and used a Kibblewhite hone to size them.
So far, so good, but I haven't covered a lot of miles on that engine yet.
Their guides also have a notch on the outside for oil seals if you've a mind to use them.


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71 A65L "Zelda"
92 BMW K100rs "Gustav"
72 T120V cafe project "Mr. Jim"
72 T150V "Wotan"
Re: Phosphor Bronze Valve Guides?
Jaybird79 #800609 03/10/20 9:05 am
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I think the triples and unit 500’s rely a lot on the top end to get clean reliable power.

I wouldn’t be pinching pennies on the top end of those motors.

The long stroke 650’s are different.


'51 C11 in a '54 C10L frame. Back on the road...
'70 Triumph Trophy 500. Next on the bench for a refresh!
'72 Triumph Tiger 650. Back on the road...

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