Valve Guide Material?

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captainkirk

Valve Guide Material?

Post by captainkirk »

I am rebuilding a Royal Enfield Bullet Motorcycle (India built model) and I have hit on a snag in the cylinder head. It appears that the factory bored the hole for one of the valve guides too large and instead of being a press fit you can push it in and out with finger pressure. The second problem is that the valve doesn't fit correctly into the guide that does press fit, it's a sloppy fit way to much slop.
I have tried new valve guides and valves and they have the same fit, so either I can sleeve the hole with an insert or I can get a bigger valve guide, I'm leaning toward either purchasing larger valve guides (don't know where?) or making one for the experience, but I don't know what type of bronze to make it out of, and a source for it.
Any help with the best solution would be greatly appreciated (either way I would like to know what type of bronze they are made from)
Skeeter5000

Re: Valve Guide Material?

Post by Skeeter5000 »

Hello Captain,

I don't know much about motorcycles, but I have rebuilt a number of heads in the past. You could check with a local engine rebuilder and see what type/size of valve guides he has that drive in. This could be from any kind of engine.

He may have something that will adapt to your engine.

Just a thought.

Good luck.
oheider

Re: Valve Guide Material?

Post by oheider »

Captain
Some guides are made of nodular cast iron--get a camshaft and turn a guide out of that. Some high performance guides are made from silicon bronze. You should be able to get some stock from an engine rebuilder supply house. Ask Hanz from Hanzenginehous that is his line of work.

Otto
Hanz
Posts: 155
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Location: Orlando
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Re: Valve Guide Material?

Post by Hanz »

Are oversize OD guides available? That would be the easiest. I have a customer that gets his Royal Enfield parts from a guy in Texas, maybe you know of the place.

Second easiest would be to modify a shelf guide, by looking at size specs in the back of a valve guide book. It would probably be available in cast, which actually wears very good. Possibly in bronze. I have always found guides that I could modify when I needed, so I don't really know what you would use for raw stock if you wanted to make custom bronze guides.

If you need help in matching, and post the Royal sizes, I can help find something close. Hanz
[url=http://www.hanzenginehouse.com]www.hanzenginehouse.com[/url]
J_Tiers

Re: Valve Guide Material?

Post by J_Tiers »

I have seen where that kind of problem was solved by knurling the valve guide to get a tighter fit. It would have to be good, since the guide takes some side forces and you don't want it to walk out.

If it is a slip fit now, it should be tighter if knurled. If it is wobbly loose, then I don't think knurling is a very good idea.
jpfalt
Posts: 982
Joined: Sun Jan 05, 2003 12:55 pm

Re: Valve Guide Material?

Post by jpfalt »

I have seeen valve guides knurled on the ID to get a tighter fit by expanding the valve guide and the knurl is then reamed to fit the valve stem. It leaves a less than 100% surface on the valve stem, but seems to be good for getting lubricant into the guide. These were bronze guides in Volkswagen engines.
Jerry B

Re: Valve Guide Material?

Post by Jerry B »

I have installed, knurled and, lined my share of valve guides.

Find a guide slightly larger on the OD than the guides you have now. Don't worry too much about the stem diameter right now. Ream the head to a press fit for them.

After installing the guides in the head, use a bronze liner to bring the ID to the size of the valve stem. Of course this means having some machine work done of you don't have the tools to install the liners.
captainkirk

Re: Valve Guide Material?

Post by captainkirk »

Thanks for your offer I won't get to measure it till later this week, I'll email you the dimensions and see if an "off the shelf" guide can be purchased, that will probably be the best solution, failing that I'll have to sleeve one. I don't like the knurling idea on this particular engine design because the side loading is fairly high.
captainkirk

Re: Valve Guide Material?

Post by captainkirk »

Thanks for the reply I will definitely need some help with reaming clearances and press fit instructions so if an off the shelf guide can't be found that fits correctly I'll go your route.
captainkirk

Re: Valve Guide Material?

Post by captainkirk »

Thanks for your post I'll get to it this weekend and see which way is best to go
captainkirk

Re: Valve Guide Material?

Post by captainkirk »

Thanks for the information on the nodular cast iron I know where a number of old shafts can be had. If the other options con't work out I might go that route.
pete913
Posts: 42
Joined: Sun Sep 07, 2003 6:51 pm

Re: Valve Guide Material?

Post by pete913 »

Having done many a valve job in my time, I have to say that I'm not a fan of any type of bronze valve guide. My experience has been that they don't stand up anywheres near as well as a nodular cast iron guide. Knurling guides works for awhile, but it's just that much less bearing surface. I'd ream the old hole oversize, and if you can't find a guide that fits, make a guide out of an old car camshaft.
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