I am having an EJ 20 rebuilt and the rebuilder swears by bronze valve guide sleeves. With anything proposed as non standard I prefer to check out claims.
Attached is my evaluation
If anybody has experience with these sleeves I would be very interested.
Bronze sleeves in valve guides
Bronze sleeves in valve guides
- Attachments
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[The extension pdf has been deactivated and can no longer be displayed.]
Are you sure about sintered bronze? There are no such claims from makers or rebuilders and any oil is going to get very hot at exhaust valve a likely to carbonise. Heat transfer is not only related to material but surface area. The sleeves I have seen have surface area substantially reduced due to many so called oil retaining grooves. What oil?
Normally heat transfers from the valve stem total surface area to cast iron. With a reduced surface area bronze interposed this will actually increase the thermal resistance and impede heat flow by a small amount. There is no way heat flow is improved.
Certainly I am concerned that rebuilders and manufacturers make dubious claims about these split bronze sleeves with no factual reliability data.
That is why I have posted to see if anybody has any experience of these in engines. Whilst an engine rebuilder may claim installing thousands without problem. What does this really mean? Seeing that most rebuild warrantees are one year. Not long for an engine life. There is no come back if failure occurrs after one year so the rebuilder would not necessarily be aware of relatively short term engine life problems.
Hope somebody has some good facts about reliability.
Normally heat transfers from the valve stem total surface area to cast iron. With a reduced surface area bronze interposed this will actually increase the thermal resistance and impede heat flow by a small amount. There is no way heat flow is improved.
Certainly I am concerned that rebuilders and manufacturers make dubious claims about these split bronze sleeves with no factual reliability data.
That is why I have posted to see if anybody has any experience of these in engines. Whilst an engine rebuilder may claim installing thousands without problem. What does this really mean? Seeing that most rebuild warrantees are one year. Not long for an engine life. There is no come back if failure occurrs after one year so the rebuilder would not necessarily be aware of relatively short term engine life problems.
Hope somebody has some good facts about reliability.
It is my experince the sintered bronze bearings are only used in somewhat lower temp applications, many in fan motors. They are usually heated in oil to remove air and then allowed to cool and draw in oil.
I cannot see them being applied to exhaust valve stems, too hot.
Nobody has yet declared any experienced benefit of the phosphor bronze sleeves for guides. Not well known I guess.
On another subject. I have used petrol to soften and remove RTV silicone.
I cannot see them being applied to exhaust valve stems, too hot.
Nobody has yet declared any experienced benefit of the phosphor bronze sleeves for guides. Not well known I guess.
On another subject. I have used petrol to soften and remove RTV silicone.
Well I have searched and searched and found one mileage experience for bronze liners.
Quote: You do not need hardened guides for unleaded fuel. Seats are a good idea but GM is still using the same old basic cast iron in their heads that has been around forever. The bronze liners are not a problem if they are installed properly.
We have even used them in both big & small block propane engines that have well over 60,000 miles on them. One is a 383 in a service truck for a propane company & the other is a 496 in a motor home.
Been using them for over 15 years & have had no problems that were the fault of the guide
But again like anything else they do have to be installed properly including broaching & honing to size.
As for seals, I like the metal encapsulated viton ones.
Quote: You do not need hardened guides for unleaded fuel. Seats are a good idea but GM is still using the same old basic cast iron in their heads that has been around forever. The bronze liners are not a problem if they are installed properly.
We have even used them in both big & small block propane engines that have well over 60,000 miles on them. One is a 383 in a service truck for a propane company & the other is a 496 in a motor home.
Been using them for over 15 years & have had no problems that were the fault of the guide
But again like anything else they do have to be installed properly including broaching & honing to size.
As for seals, I like the metal encapsulated viton ones.
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discopotato03
- Senior Member
- Posts: 2134
- Joined: Sun Mar 18, 2007 9:29 am
- Location: Sydney
One brand name you could search is K Line , I think my exhaust guides were K Lined which is cheaper and easier than R/R guides in an aluminium head .
Basically the machine shop drills and runs a coarse thread tap throught the existing guides . The liner is inserted and a ball shaped mandrel is pushed through the liner to expand and lock it into the guide . From memory the liner is finish reamed to suit the valve stem and whatever clearance is specified .
To do this successfuly the valve stems need to be parallel and uniform , pointless having a good guide and a tapered valve stem .
Anyway search K Line , should show you how they work . I'm only using memory and its a lot of years since I watched someone do it .
Cheers A .
Basically the machine shop drills and runs a coarse thread tap throught the existing guides . The liner is inserted and a ball shaped mandrel is pushed through the liner to expand and lock it into the guide . From memory the liner is finish reamed to suit the valve stem and whatever clearance is specified .
To do this successfuly the valve stems need to be parallel and uniform , pointless having a good guide and a tapered valve stem .
Anyway search K Line , should show you how they work . I'm only using memory and its a lot of years since I watched someone do it .
Cheers A .
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discopotato03
- Senior Member
- Posts: 2134
- Joined: Sun Mar 18, 2007 9:29 am
- Location: Sydney
thanks discopotato03 for your useful info. I have in fact read all these and familiar with process. What I have been looking for is actual experience in operation. Rebuilders claim a lot and favour bronze liners , it is simple and low cost. It is very hard to find anybody quoting actual operational experience. K-line show comparative tests that look promising.
I guess that if there are problems there would be plenty of posts. So it would appear that no news on op performance is good news.
I hope you read my document attached to the first post where I have covered claims and raised issues and risk factors.
I guess that if there are problems there would be plenty of posts. So it would appear that no news on op performance is good news.
I hope you read my document attached to the first post where I have covered claims and raised issues and risk factors.
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steptoe
- Master Member
- Posts: 11582
- Joined: Thu Oct 06, 2005 10:00 am
- Location: 14 miles outside Gotham City
BREAKING NEWS
Was asking a head shop guy about this odd tag hanging from a valve guide of a head that was apparently serviced 10 - 20,000km ago. Sounds to be what can be described as a brass insert sleeve similar to K____ if not same, a good for race application with stainless valves, or an 'affordable' repair option but he says if he was to do a head for good service life it is cast iron insert with std 'black' valves . That is how mine will be done when it comes time for more sheckles to be spent.
Was asking a head shop guy about this odd tag hanging from a valve guide of a head that was apparently serviced 10 - 20,000km ago. Sounds to be what can be described as a brass insert sleeve similar to K____ if not same, a good for race application with stainless valves, or an 'affordable' repair option but he says if he was to do a head for good service life it is cast iron insert with std 'black' valves . That is how mine will be done when it comes time for more sheckles to be spent.