bronze valve seats

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bangkokbob
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bronze valve seats

#1

Post by bangkokbob » Fri Sep 13, 2019 2:14 pm

Hi all in Panhead land.

I am doing my heads for the first time.I have the bronze 2 cut seats that should clean up with a 3 cut.
Now my question is -

Will bronze seats run OK with lead free gasoline?

I will be replaceing the HD valves with kibblewhite valves, new KW valve springs and cast KW valve guides.

Regards in advance B.B.



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Re: bronze valve seats

#2

Post by RooDog » Fri Sep 13, 2019 2:38 pm

I see no reason why the stock, cast in, bronze alloy seats will not work with your KW valves. I would rather leave the stock seats in place than to trust pressing in replacement seats and risking having one come loose and falling out. Do you feel lucky? Also, there is a lot of mythology regarding unleaded fuel, most of it is gloom and doom babbling. Unless you are an abusive racer, running that vintage engine hard and fast for long periods of time I would feel the stock seats to be just fine unless they are thoroughly worn out, and then perhaps a slightly oversize valve will take care of that issue. Shovelhead intakes are 1/16 OS, and I bet KW offers OS Ex valves.....
Just my Opinion. I may be wrong, but I doubt it.....
...RooDog....

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Re: bronze valve seats

#3

Post by Buddhahoodvatoloco » Fri Sep 13, 2019 10:24 pm

Ahh kibblewhite, music, music.

bangkokbob
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Re: bronze valve seats

#4

Post by bangkokbob » Sat Sep 14, 2019 1:51 am

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bangkokbob
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Re: bronze valve seats

#5

Post by bangkokbob » Sat Sep 14, 2019 7:40 am

Hi all.
Just to be more specific.

I don"t intend to replace valve seats. These seem to be in good condition.
Will these seats be OK with unleaded fuel?
The KW valves would be OK with unleaded fuel.
So do I need to continue to use valve added lubricant to protect the seats?

Regards B.B.

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Re: bronze valve seats

#6

Post by panhead » Sat Sep 14, 2019 8:24 am

If they are in good condition I wouldn't replace them. I don't believe the impact of running unleaded fuel will manifest itself in short term.

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Re: bronze valve seats

#7

Post by Andygears » Sat Sep 14, 2019 2:09 pm

Down here in Daytona, the AMCA sunshine chapter have a lot of panhead guys. They have become “The Panhead Committee”. As a committee, most if not all of them, don’t replace seats. The cast in bronze seats are cherished and seem to be durable because most of these guys ride a lot more than I. Like to Milwaukee for the anniversary last year, to Davenport, to Waseon, etc. I never heard any of them complain that the seats were the problem when they dropped a valve, or otherwise broke their bike. I have heard of multiple cases of replacement seats dropping out due to heat expansion of the aluminum heads.

Think of it like “Original Paint”: It’s only original once, and although not perfect, it’s still better than any replacement.

My two cents
Andygears

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Re: bronze valve seats

#8

Post by hdmarkus » Sat Sep 14, 2019 6:34 pm

I had often discussed this with friends. Conversion to lead free is money making. If the original valve seats are still good, I would leave the original ones.

Markus

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Re: bronze valve seats

#9

Post by Bone Head » Sun Sep 15, 2019 10:15 am

I had a highly respected Harley mechanic (R.I.P. Boone) tell me that the bronze valve seats were just as hard if not harder than the new unleaded seats everyone was converting to in the '80s. I did research (metallurgical engineer at work) and found he was correct. With new valves they should be fine.

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Re: bronze valve seats

#10

Post by bangkokbob » Sun Sep 15, 2019 11:31 am

Thanks Bone Head.

Thats the answer and what I thought I had read somewhere in the past.
As I originally stated doing the heads my first time and at 55.5k miles it looks like possibly since it left the factory.
I will also be putting in new KW springs so motor should outlast me now.

Regards B.B.

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Re: bronze valve seats

#11

Post by dontsink » Sun Sep 15, 2019 3:29 pm

Bone Head wrote:
Sun Sep 15, 2019 10:15 am
I had a highly respected Harley mechanic (R.I.P. Boone) tell me that the bronze valve seats were just as hard if not harder than the new unleaded seats everyone was converting to in the '80s. I did research (metallurgical engineer at work) and found he was correct. With new valves they should be fine.
Bronze never can be as hard as the replacement inserts made of steel.

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Re: bronze valve seats

#12

Post by flatboy1950 » Sun Sep 15, 2019 3:39 pm

I guess it depends on the bronze ... Aluminium bronze valve guides cannot be cut with a reamer & have to be honed out to size ....

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Re: bronze valve seats

#13

Post by RooDog » Sun Sep 15, 2019 3:42 pm

No matter how hard one tries, or how abusive a rider is, the factory bronze seats will never come loose and fall out destroying an engine. That is a fact, not an opinion....
....RooDog....

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Re: bronze valve seats

#14

Post by dontsink » Thu Sep 19, 2019 8:04 am

I found this article in the web, basically it says, when done right, the seats won´t come out. Even with aluminium heads.
It seems, that the bad experience of failed valve seats is related to not insert the seats correctly.
https://www.aa1car.com/library/ar993.htm

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Re: bronze valve seats

#15

Post by Bone Head » Thu Sep 19, 2019 11:49 am

dontsink wrote:
Thu Sep 19, 2019 8:04 am
I found this article in the web, basically it says, when done right, the seats won´t come out. Even with aluminium heads.
It seems, that the bad experience of failed valve seats is related to not insert the seats correctly.
https://www.aa1car.com/library/ar993.htm
That's a good article with automotive applications, which are water cooled and vibration-free compared to our pans. I think air cooled motors will run hotter and thermal expansion rates are more critical. Could be another reason a pan has bronze seats is the expansion rates for bronze and aluminum are pretty close.

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