Author Topic: colisbro guides  (Read 307 times)

Online sean

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colisbro guides
« on: 28.03. 2020 19:34 »
hi
what are people using to hone colisbro material valve guides after fitting to the head  and where are you buying hone from ?
thanks
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Offline RDfella

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Re: colisbro guides
« Reply #1 on: 28.03. 2020 20:25 »
As far as I know a flexi-hone is what's required.  I see MSC (sales@mscdirect.co.uk) list them.
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Online sean

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Re: colisbro guides
« Reply #2 on: 28.03. 2020 21:46 »
i am across the pond in canada been looking on kibblewhites site and a couple of others they say their hones arent made for this material

I have e mailed srm to see if they sell a hone but havent got a reply .

thanks
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Online Klaus

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Re: colisbro guides
« Reply #3 on: 29.03. 2020 08:43 »
I never honed a colsibro guide. Get them  from SRM in different oversizes in combination with the valves. There is no need to hone them.
I use a spezial selfmade drifting tool with a spigot cooling the guidewith the tool in the freezer and hot up the head in an oven as hot he can.
Usual the guide is slipping easy and I give only one or two punches to be sure the guide is sitting perfect.

cheers Klaus
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Offline Fergie

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Re: colisbro guides
« Reply #4 on: 12.04. 2020 00:56 »
hi
what are people using to hone colisbro material valve guides after fitting to the head  and where are you buying hone from ?
thanks

I'm making my own guides and i will ream them after fitting in the head. A hone is not required just a good brand of reamer that will give the right clearance.
A problem with hones is that they must be kept moving from top to bottom (in and out) in the valve bore and you need to flood the guide with cutting oil when honing. It's the same as honing your barrels only on a much smaller scale.
Its an engineering shop job unless you have the right equipment whereas you will get good results with a reamer, if care is taken.

Hope that helps. Fergie. 
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Offline BSAmoto

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Re: colisbro guides
« Reply #5 on: 12.04. 2020 22:42 »
Got some honing " stones" which I use in all guides that I make for lots of cylinderheads. Some of them contain diamond pieces that are glued/sintered in metal, others are made with siliciumcarbide. I hone them before inserting in the head to slide just over the valve stem. Depending on the ratio between outer diameter and valve stem, many valve guides shrink where they are sitting in the head as the hot head contracts the guide a bit when cooling down so they end up a bit like an hourglass shape. (DonĀ“t overheat the aluminium heads - above 200 centigrades the aluminium loses a lot of strength)So far only the Norton 850 with the silly 16mm guides does not contract measurably.
Once the head has cooled down completely a quick session on the sunnen hone brings the perfect shape and correct diameter back. I tried (expensive) reamers many years ago but found several problems that put me off: good bronce guide materials are quite difficult to ream properly, valve stem diameters vary in each batch that I can buy - sometimes more than 3/100 mm, and finally I repair so many different heads that I would have to buy dozens of reamers to have the correct size at hand.
cheers, Harty
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