Questions about heating cylinder head to pull out the valve guides

dobba99 said:
Same result as hammering the guide out = a ruined hole
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Even when heated to 300F?

Comstock does them that way, (has a FAST puller/pusher) HOT.

While I've machined/ground/cut/welded things to reduce their tight internal fit, and if a person possess the ways & means, great.
But hot in and out has worked SUCCESSFULLY for a lot of people, for a long time.
 
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Over the years past over 90% of guides were removed with heat and drifting them out, and hopefully they heated the heads. A lot of it is how you prepare to do it and the prep work before and during the job. I did start to use the tool to install guides and rigged up ways to do it as quickly as possible. It seems like with a threaded tool to "pull" them in, they when in "straighter" or truer to the valve seat.

It is just not a job for a "first timer" with no practice or sense of feel. Luckily in my Town we have a machine shop that does a motorcycle valve job very reasonable and fast, and does a good job of it. The main thing is to use good new parts and use the proper stem clearance that is recommended. NOT the sloppy stem clearance in shop manuals.
 
If you are installing bronze guides by driving them in, hot or not, be sure and have them reamed to proper clearance on the valve stem. They tend to collapse a bit during installation.
 
marshg246 said:
Are you positive you need to change them? It's not a job to do "just because"!

Get a laser thermometer. When the aluminum around the guide is at least 150C and no more than 200C you're fine. Lots of ways to do it. Cold or preheated makes little difference - think about how the engine runs! If it doesn't move, get it hotter rather than hit it harder. Of course, you're supposed to pull them out and in - I never have that tool, but I have the right sized drift so I drift them out and in. However you do it - be sure you start absolutely straight.
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.
 
Stephen Hill said:
I don't claim to be a diva machinist, but I do have some talent, a half decent mill, lots of milling cutters, and a large adjustable angle plate. I found setting up the head to mill the guides out a royal pain in the ass. My mill has some limitations on vertical capacity. Reaching the tool deep enough to complete the boring operation was a challenge. Getting the angle correct enough so I felt confident in leaving a thin guide without compromising the bore was not easy. Halfway through I gave up and resorted to a drift and heat.
I wonder how many shops you took your head to would say they would mill it out for you? And actually do it once you left the shop? Pounding them out or pulling them out would be 10 times faster. Are you really going to pay them 10 times as much to machine them out?
Unless you are doing it in your own shop, with all the right tools and skills, the milling approach sounds kind of unlikely to me.
But then maybe I am just bitter and twisted because I resorted to the caveman approach.
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If your drilling out guides to leave say. 060" aside, drill from port side and stop before spring seat, you can do this by hand easily, this should be enough to relieve interference, heat head and tap out. K liners are the way to go, unless you have to do guides.
 
I have ordered new valves and will check how much slop they have in the existing valve guides when they arrive. Machine shop said that they do valve guide liners, but that the liners cannot be used on Phosphor Bronze guides, only cast iron. Luckily my existing guides attract a magnet so valve guide liners can be used
Dennis
 
I would not use cast iron valve guides. If a valve clips a piston, the guide can facture and a small piece of cast iron can damage a valve seat - but do no other damage. It is difficult to detect.
 
DennisMo said:
Machine shop just reported that the guides are too worn to sleeve so I will get new Phosphor Bronze guides when they tell me the sizes
Thanks
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Change machine shop, Think the sleeves are like a cylinder liner, you have to bore the guide to accept the liner. I think that machine shop is telling you porkies. (lies) they probably haven't got the liner equipment and are talking you into a more expensive job. Have you watched the K liners vid on Post no6 ? you see them boring the guide out to take the bronze liner. Did you measure the valve stems and guides? or did you just hand the head over to the machine shop?
If it requires new guides and they won't (or can't) fit liners ask them to do the following. If they remove the old guides make sure they machine out the old guide as per my post 17. Ask to see the old guides after they have been removed, and if they look intact they have not been machined out., they will have been pulled or hammered out and have enlarged the hole in the head. They should look something like the photo in post 17. If they say that it now needs oversize guides they have ruined the hole in the head as per my post 5. Did you check how much wiggle a new valve is in the guide before approaching the 'machine shop'?
 
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I did look at the K-liner info. There was a lot of wiggle in the guide. Old owner had done new valves at some point but not guides. The valve guides actually seemed to have very little wear. I could not find any ridges on the stem. The Shop does do K-liners and said that guides are too worn to drill guide to accept liner.

The shop has not said anything about phosphor Bronze versus regular guides. Those were my words. I gather that phosphor Bronze are recommended as they are better lubricating material. Love to get ll your thoughts on this
Dennis
 
According to this advice

When Guides Cannot Be K-Lined
  • Excessive Wear: If the original guides are worn more than .030 inches (approx. 0.76mm) or are otherwise severely damaged, they are generally not candidates for liners.
  • Cracks: If the guide itself or the surrounding cylinder head casting is cracked, a liner will not fix the structural integrity.
  • Insufficient Material: On some small engines with 4mm or 5mm valve stems, there may not be enough parent material to safely bore the guide to accept a liner.
  • Material Thinning: If the guide is already quite thin (e.g., in certain bronze guide applications), adding a liner might make it too weak, risking fracture.
There must be a large amount of wear, 0.76mm is huge. Ask them what wear they can see, if its a lot less that 0.76mm then take the head to a better K-linering outfit.
 
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DennisMo said:
I did look at the K-liner info. There was a lot of wiggle in the guide. Old owner had done new valves at some point but not guides. The valve guides actually seemed to have very little wear. I could not find any ridges on the stem. The Shop does do K-liners and said that guides are too worn to drill guide to accept liner.

The shop has not said anything about phosphor Bronze versus regular guides. Those were my words. I gather that phosphor Bronze are recommended as they are better lubricating material. Love to get ll your thoughts on this
Dennis
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The standard guides for your engine are iron. the "Go faster stuff" section of AN does have bronze guides: https://andover-norton.co.uk/en/shop-category/69/go-faster-stuff-norton

I have no clue if they are "Phosphor Bronze", they are CW713R: "CW 713R is a high tensile brass which is alloyed with aluminum, manganese and silicon etc. By alloying brass with strength-increasing elements, you get an alloy that is almost as hard as aluminum bronze, but considerably easier to process. The material also has good corrosion and wear resistance."

No, what about the "size" you mentioned.
 
General thoughts - take with a grain of salt:

I've replaced lot of Norton and Triumph guides. I've never had to recut the seats and they have lapped in without problem.

Unless you have a way to setup the head perfectly in a mill when lining guides will surely require at least recutting the seats if not replacing them.

If you do Norton heads often and have a mill, then making a fixture would make lining guides easy.

Watch Jim, Comstock do it here:
 
kommando said:
According to this advice

When Guides Cannot Be K-Lined
  • Excessive Wear: If the original guides are worn more than .030 inches (approx. 0.76mm) or are otherwise severely damaged, they are generally not candidates for liners.
  • Cracks: If the guide itself or the surrounding cylinder head casting is cracked, a liner will not fix the structural integrity.
  • Insufficient Material: On some small engines with 4mm or 5mm valve stems, there may not be enough parent material to safely bore the guide to accept a liner.
  • Material Thinning: If the guide is already quite thin (e.g., in certain bronze guide applications), adding a liner might make it too weak, risking fracture.
There must be a large amount of wear, 0.76mm is huge. Ask them what wear they can see, if its a lot less that 0.76mm then take the head to a better K-linering outfit.
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You can measure the worn guide with a drill bit used as a gauge. The valve stems are a couple of thou under 5/16" and the guide bore reamed to 5/16" If you cannot get a 8.5mm (11/32") drillbit into the guide, the guides are suitable for K-liners. Report back what size the worn guides are.
 
DennisMo said:
Machine shop just reported that the guides are too worn to sleeve so I will get new Phosphor Bronze guides when they tell me the sizes
Thanks
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"The valve guides actually seemed to have very little wear."




Does anyone else see the lunacy going on here?

This thread goes around in circles.
 
dobba99 said:
The valve guide removal section of the workshop manual should be deleted. Heating the head to remove the guides and then drifting them out will ruin the hole in the head. You will remove some little lumps of alloy along with the guide. This is because the hard carbon adhering to the guide will pick up and gall dragging the alloy with it. Even if you blast clean the guide this will happen. The way to ensure that the guide comes out clean is to machine most of the guide away with a sized counterbore, leaving a thin shell of cast iron that then will pull or drift out without galling.
If you do drift the guides out, you WILL be fitting oversize guides because std size guides will just drop in as you will have opened the holes up. Also the holes won't be straight and round so its a trip to an engine reconditioners to get them reamed to suit.
Removing the guides by machining the inside of the guide away leaves the hole in the head intact so refitting std size guides is easy (shrink them in pipe freeze spray) and fit them to the heated head. A big plus is that the valve seats will only need lapping in, no seat cutting required.
Why do you think they sell oversize guides? It is because this 'hole ruining' takes place!
I sometimes think the workshop manual section on valve guide removal was included to create business for engine reconditioners and repeat sales for oversize valve guides.
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Just a thought. On 850 heads could you remove the C clip and drift the guide into the combustion chamber?
 

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