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Valve Guides Reaming And Clearance


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#1 JonnyAlpha

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Posted 14 April 2021 - 09:30 PM

Need some advice on valve guides, reaming and clearance.

 

I'll be fitting cast iron valve guides and understand the ID is 9/32 or 7.14mm, is this before or after reaming?

 

If reaming (and I have found some info suggesting that cast iron guides don't get reamed), what size reamer do I need and where can I get one?

 

I understand from searching on here that the clearance should be 0.012"

 

Many thanks 



#2 ACDodd

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Posted 14 April 2021 - 10:04 PM

Valve guides close up when inserted. The finished size is that produced by a 9/32” reamer. HSS reamers wear quickly, I have had much more success with a solid carbide reamer. MSC direct sell a budget solid carbide chucking reamer which is what I now use.
I used HSS reamers for years the trick to getting them to last is to modify them.

Ac

#3 Turbo Phil

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Posted 14 April 2021 - 10:25 PM

The guides always need reaming to provide clearance regardless of material type.

Phil.

#4 dotmatrix

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Posted 15 April 2021 - 08:38 AM

I bought an adjustable reamer that I use because when I change valve guides but not valves, the size differ a little bit from valve to valve especially in engines that have had e.g a burned valve changed, so the guides may not need to be the same diameter all of them.

I'm not sure its the correct practice but this is what I do



#5 JonnyAlpha

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Posted 15 April 2021 - 10:16 AM

Should only be doing a couple of heads, unless I am successful then I might start doing other peoples, nothing like a bit of competition 😉
I’ll look at the carbide ones from MSC but if they are Uber expensive, I’ll get a HSS one.

Thanks for the info.

#6 JonnyAlpha

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Posted 17 April 2021 - 08:28 AM

Found a 9/32 Hand Reamer here, although it does not specify the length of the tool so I have messaged the company.

 

I already have a T Bar which I bout for cleaning out threads.

Wonder if I could use this in a bench drill?



#7 JonnyAlpha

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Posted 19 April 2021 - 01:35 PM

Had a reply from the company selling these.
Details are:
Overall Length: 108mm.
Cutting Length: 60mm.

Don’t have a head with me at the mo, but as a standard deck is 70mm, these reamers should be ok.

#8 Icey

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Posted 19 April 2021 - 02:29 PM

Found a 9/32 Hand Reamer here, although it does not specify the length of the tool so I have messaged the company.

 

I already have a T Bar which I bout for cleaning out threads.

Wonder if I could use this in a bench drill?

I've used Arceuro to buy quite a bit of machine stuff. The cutters I've had from them have been good. I did chip an end mill but that was by being stupid rather than the tool.






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