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Replacing valve guides. B44 #789653 11/10/19 12:51 am
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Frank the Welder Offline OP
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I need a complete valve job. The combustion chamber looks great, seats are flush but valve guides are really bad. I have access to a valve seat grinder but seek some advice on removing/installing guides and getting everything squared up. ill have a look at the grinder in a few days. Thank you, Frank

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Re: Replacing valve guides. B44 [Re: Frank the Welder] #789667 11/10/19 7:21 am
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kommando Online Content
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Removing and replacing guides runs the risk of scraping the head, look at getting the current guides lined, should be easy to do for a guide liner as VW,s guide bores are dimensionally very close.

Re: Replacing valve guides. B44 [Re: kommando] #789750 11/10/19 11:10 pm
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Frank the Welder Offline OP
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Interesting.. thanks.

so how much play at full lift is considered acceptable?

Last edited by Frank the Welder; 11/10/19 11:13 pm. Reason: lack of knowlege.
Re: Replacing valve guides. B44 [Re: Frank the Welder] #789788 11/11/19 8:55 am
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Mitch Offline
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I've done a few (quite a few) I've also done a bunch of aircraft cylinders in my career as a professional mechanic, working at an engine repair station. and done cars and others too. so... heat the head to about 600F (there are crayon markers to indicate temp) (or heat until spit sizzles right off the head),a slide hammer that flows cold water through the guide mandrill is best, but a chilled mandrel will work. let it chill 10 seconds, bonk it out and be ready with the new guides. or, install guides later, but in any case guides need to be chilled in the freezer overnight, and the head needs to be back up at 600. oil them and don't fool around, poke them in the hole and drive them home. when done check the guide bores, they get tighter. the seats will need to be recut for sure. I have switched to Neweay cutters 20 years ago... its the easiest way to go

Re: Replacing valve guides. B44 [Re: Frank the Welder] #789791 11/11/19 9:11 am
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Mitch Offline
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the wobble method for checking clearance... very subjective. best to measure

Re: Replacing valve guides. B44 [Re: Mitch] #789879 11/12/19 12:32 am
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Frank the Welder Offline OP
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Originally Posted by Mitch
I've done a few (quite a few) I've also done a bunch of aircraft cylinders in my career as a professional mechanic, working at an engine repair station. and done cars and others too. so... heat the head to about 600F (there are crayon markers to indicate temp) (or heat until spit sizzles right off the head),a slide hammer that flows cold water through the guide mandrill is best, but a chilled mandrel will work. let it chill 10 seconds, bonk it out and be ready with the new guides. or, install guides later, but in any case guides need to be chilled in the freezer overnight, and the head needs to be back up at 600. oil them and don't fool around, poke them in the hole and drive them home. when done check the guide bores, they get tighter. the seats will need to be recut for sure. I have switched to Neweay cutters 20 years ago... its the easiest way to go


Thank you for your time and thorough explanation. I have a lot of what is needed already and will research Neweay cutters.

Ill also get some specific measurements for the valve stem play. and will go from there. Thanks again, Frank

Re: Replacing valve guides. B44 [Re: Mitch] #789934 11/12/19 11:34 pm
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Frank the Welder Offline OP
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Originally Posted by Mitch
the wobble method for checking clearance... very subjective. best to measure


That Neweay system is amazing. It sounds configurable so the cost of entry for personal use is reasonable.

I measure the valve head movement at .3" lift and it was over .050"+ out typically.

I suspect the centerline of the valve stem isn't in the middle of the valve seat. The valve guide is by far the most worn part of the bike.

Re: Replacing valve guides. B44 [Re: Frank the Welder] #789953 11/13/19 8:02 am
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I’ve found with some valves that I buy for the A65 that they are a fraction over size on the stem, it means that an old valve comes out that wobbles, reamer goes in the guide and I end up with the new valve that spins but without feeling any wobble. I’ve also bought some valves which are under size also from different suppliers and they quality hasn’t been quite as good as the other (SRM) if you can find a decent place that does K-liners these are good to have and saves the risk of the head being damaged in the process. But find a shop with recommendations for doing them. Some places are good and some not so.


beerchug
Re: Replacing valve guides. B44 [Re: Allan Gill] #789998 11/13/19 11:57 pm
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Frank the Welder Offline OP
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Originally Posted by Allan Gill
I’ve found with some valves that I buy for the A65 that they are a fraction over size on the stem, it means that an old valve comes out that wobbles, reamer goes in the guide and I end up with the new valve that spins but without feeling any wobble. I’ve also bought some valves which are under size also from different suppliers and they quality hasn’t been quite as good as the other (SRM) if you can find a decent place that does K-liners these are good to have and saves the risk of the head being damaged in the process. But find a shop with recommendations for doing them. Some places are good and some not so.


My Intake valve stem was .3085" top to bottom and round to the 10th.

I know there are a lot of people with more experience than myself but there are a clear set of procedures for this type of work and I am able to follow instructions if nothing else. I may to a little large on the valve head size. I need to do some research yet.

I found this 2K (F) oven and the head fits right in there. 600 should be easy!

[Linked Image from live.staticflickr.com]Untitled by barnstormerbikes, on Flickr

Re: Replacing valve guides. B44 [Re: Frank the Welder] #790008 11/14/19 2:49 am
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600 F. seems way to hot for an old piece of aluminum

Re: Replacing valve guides. B44 [Re: Frank the Welder] #790020 11/14/19 6:28 am
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600F is fine. you can easy go to 800 is your temperature measuring equipment is good. the best way to do this is punch out the old guide, cool to room temp and measure the bore. the new guide needs to be .0005 to .0015 bigger than the hole, and maybe as much as .001 more on the exhaust side. you can only know this by precision measurement and good technique. the fit is tight by design. if too loose, the guide will move when hot. if too tight... you won't get it in the hole, and a cast iron guide might break in the process. I would not try any fit tighter than .0015 unless you can obtain the heat (600 minimum). again, chill the guides in oil. the guides may need to be reamed after install. the seats will absolutely need to be re-centered

Re: Replacing valve guides. B44 [Re: Frank the Welder] #790025 11/14/19 9:35 am
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To remove the danger of carbon deposits dragging on the head guide bore as the oil guide is forced out, and creating scores that generate oil leaks, the guide bottom needs removing if possible or at least being cleaned back to bare guide material.

Re: Replacing valve guides. B44 [Re: kommando] #790081 11/14/19 11:23 pm
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Frank the Welder Offline OP
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Originally Posted by kommando
To remove the danger of carbon deposits dragging on the head guide bore as the oil guide is forced out, and creating scores that generate oil leaks, the guide bottom needs removing if possible or at least being cleaned back to bare guide material.


Good thinking. I am still on the fence with with guide removal.

Re: Replacing valve guides. B44 [Re: Mitch] #790082 11/14/19 11:34 pm
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Frank the Welder Offline OP
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Originally Posted by Mitch
600F is fine. you can easy go to 800 is your temperature measuring equipment is good. the best way to do this is punch out the old guide, cool to room temp and measure the bore. the new guide needs to be .0005 to .0015 bigger than the hole, and maybe as much as .001 more on the exhaust side. you can only know this by precision measurement and good technique. the fit is tight by design. if too loose, the guide will move when hot. if too tight... you won't get it in the hole, and a cast iron guide might break in the process. I would not try any fit tighter than .0015 unless you can obtain the heat (600 minimum). again, chill the guides in oil. the guides may need to be reamed after install. the seats will absolutely need to be re-centered



I have two measuring instruments (one is Fluke). Thanks for the solid numbers.

Re: Replacing valve guides. B44 [Re: quinten] #790083 11/14/19 11:42 pm
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Frank the Welder Offline OP
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Originally Posted by quinten

600 F. seems way to hot for an old piece of aluminum


Don't forget this motorcycle was on fire and the fuel tank and carb burned to nothing which is 1000F or so.

Re: Replacing valve guides. B44 [Re: Frank the Welder] #790248 11/16/19 6:26 pm
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John Healy Offline
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Frank I checked out your web sit I recommend other members to do the same. Just google "frank the welder bellows falls" I have to admit you are a good welder.
As such you understand that aluminum expands with the application of heat. Now a lot of these heads have valve seats that are held into the head by an interference fit.
These aluminum British motorcycle heads are made from a low-expansion alloy, with a coefficient of expansion of around .00002" per °C. At 300°C (572° F) you will see around .006" expansion.

Even when a cast iron is chosen for the seat that is also a low expansion variety, they are fit with around .004" to .006" interference. So just because you can, I think you can see why you shouldn't.

The common recommendation in Factory manuals is to heat the head in boiling water when removing, or installing, guides. The trick when heating aluminum, whether it be a head to remove or install a guide, aluminum cylinder to remove or replace a sleeve or crankcase to remove or install a bearing it is important to heat it to around 212°F and let the entire casting soak in the heat to reach this temperature.


Re: Replacing valve guides. B44 [Re: John Healy] #790388 11/17/19 10:09 pm
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Frank the Welder Offline OP
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Originally Posted by John Healy
Frank I checked out your web sit I recommend other members to do the same. Just google "frank the welder bellows falls" I have to admit you are a good welder.
As such you understand that aluminum expands with the application of heat. Now a lot of these heads have valve seats that are held into the head by an interference fit.
These aluminum British motorcycle heads are made from a low-expansion alloy, with a coefficient of expansion of around .00002" per °C. At 300°C (572° F) you will see around .006" expansion.

Even when a cast iron is chosen for the seat that is also a low expansion variety, they are fit with around .004" to .006" interference. So just because you can, I think you can see why you shouldn't.

The common recommendation in Factory manuals is to heat the head in boiling water when removing, or installing, guides. The trick when heating aluminum, whether it be a head to remove or install a guide, aluminum cylinder to remove or replace a sleeve or crankcase to remove or install a bearing it is important to heat it to around 212°F and let the entire casting soak in the heat to reach this temperature.


Thanks for the kind words. We are all good at something!

That all sounds fine with me. There is nothing like direct experience with a certain procedure and I don't want to drop the valve seats out during the process. I think it will be fun the make a water-cooled guide extractor. I have an old pump from a TIG torch cooler that I could use and use a air operated rivet driver to do the hard work. Since I am going to remove/replace at different times, I will have some info from the extraction to work from. Thanks for your input.

Re: Replacing valve guides. B44 [Re: Frank the Welder] #790391 11/17/19 10:26 pm
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There are those that have stopped driving out the valve guides. With the modern valve equipment (Serdi (form tool) and Newen (single point) ) they are able to bore out the guide saving the head from having carbon leaving striations in the hole for oil to drain into the port. Then instead of driving the guide into the head they use a threaded rod assembly to draw the guide into place. This makes sure the guide stays aligned with the original guide hole. This is especially helpful with triumph heads as the guide does not have 360° support for the full length of the hole. As such the guide tends to drift out of line and you have to remove a lot of seat material to get a decent valve seat. This is why you see so many Triumph heads with sunken valve seats.

It is interesting to note that Triumph pressed the guides into the head without heating the head. They just applied a bit of grease and pressed the guide into the head with a device that insured the guides went in straight. I admit this is not common practice in the industry.


Re: Replacing valve guides. B44 [Re: John Healy] #790650 11/20/19 12:38 am
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Frank the Welder Offline OP
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Originally Posted by John Healy
There are those that have stopped driving out the valve guides. With the modern valve equipment (Serdi (form tool) and Newen (single point) ) they are able to bore out the guide saving the head from having carbon leaving striations in the hole for oil to drain into the port. Then instead of driving the guide into the head they use a threaded rod assembly to draw the guide into place. This makes sure the guide stays aligned with the original guide hole. This is especially helpful with triumph heads as the guide does not have 360° support for the full length of the hole. As such the guide tends to drift out of line and you have to remove a lot of seat material to get a decent valve seat. This is why you see so many Triumph heads with sunken valve seats.

It is interesting to note that Triumph pressed the guides into the head without heating the head. They just applied a bit of grease and pressed the guide into the head with a device that insured the guides went in straight. I admit this is not common practice in the industry.


(I deleted my original reply which was off topic)

Boring out the guide to remove it is a great idea. The valve seat is still in original location so I should be able to use that for reference. I can't tell for sure but it looks like the valve guide hole in the port is at an angle and not counterbored which seems like what you are talking about. I wonder if it could be avoided if the guide was trued with a mill cutter before reaming?





Last edited by Frank the Welder; 11/23/19 11:59 pm.
Re: Replacing valve guides. B44 [Re: Frank the Welder] #790676 11/20/19 12:30 pm
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When guides are replaced the valve seat is re cut to suit, guide wear is not from seat missalignment , it comes from poor rocker geometry, not much you can do about that except play with pushrod length. Guide materials are better now ( if you look for the good ones). Re lining guides has a lot to be said for it, removing guides can bring fresh problems.


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Re: Replacing valve guides. B44 [Re: Frank the Welder] #790688 11/20/19 3:22 pm
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I made a tool similar to the factory one, an aluminum cylinder with a 45 degree angle on the seat side and a long rod threaded above the top of the fitted guide. A bronze pusher block (from an old guide) and long coupling nut. The cylinder keeps the guide rod square with the seat when pushing it in. The top of the guide will collapse slightly from the load and it has to be reamed afterwards. I use Dow 340 silicone heat sink compound on the guide as a lube and to aid the heat transfer to the head.
The whole arrangement could be inverted also with the rod going through the pusher block, guide and head, coming out the seat block. With that arrangement a ball thrust bearing could be used against the block to reduce the friction.

Re: Replacing valve guides. B44 [Re: gavin eisler] #791124 11/24/19 12:36 am
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Originally Posted by gavin eisler
When guides are replaced the valve seat is re cut to suit, guide wear is not from seat missalignment , it comes from poor rocker geometry, not much you can do about that except play with pushrod length. Guide materials are better now ( if you look for the good ones). Re lining guides has a lot to be said for it, removing guides can bring fresh problems.


Over the past few weeks I have researched the cost of parts to rebuild /upgrade the motor for acceleration and it's not working out. I am thinking about a trials bike. As a powerplant the B44 seems to be pretty ideal in stock form and very cost effective and I don't need remove the bumps in the ports.


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