Reaming C630 valve guides

I ordered a new set of 750 valve guides from OldBritts and was sent a set of Kibblewhite's C630 Bronze alloy ones. Looking at Kibblewhite's website, they warn not to use HSS reamers or carbide reamers on C630 alloy. These guides are 0.3105 as received and factory are 0.3135 (nominal) so I'm sure some metal will need to be removed. I haven't miked the valve stems yet (new valves).

How do you size these C630 guides? Diamond brush hone?

You would be at them a long time with just a brush hone. And they would likely end up bell mouthed.
I use a carbide reamer to take them to <.002 under finished size and then use a Sunnen guide hone to finish them. Jim

Actually, I think you are misreading Kibblewhite's warning. They are saying that the carbide reamers they sell are specifically made for use with their cast iron or manganese bronze valve guides, but should not be use on C630 bronze guides. I think that only applies to their specific reamers. Carbide reamers have been the standard tool for reaming bronze guides for a long time. We've always been advised against using high speed steel reamers in bronze guides because they go dull so fast. I've verified that by sad experience. The HSS reamers work fine on the stock cast iron guides. The usual recommendation now is to use carbide reamers and then finish with a hone. It used to be common to just ream the guides after installing, and many British bikes were done that way with no problems. It helps that the Commando valve stem is large diameter by today's standards, so doesn't require as much attention to guide finish as modern engines with skinny valve stems. Still, the best way is to ream with a carbide reamer meant for that purpose, and then hone, as Jim does. I did a lot of bronze Commando guides back in the day with a reamer and brush hone, and they worked just fine. I did eventually buy a guide hone, mostly for the skinny valves in Japanese bikes, and now also use it for Nortons.

Ken

I have used a HSS reamer on manganese bronze guides also, but these are the first C630 high nickel bronze guides for me. I don't know why Kibblewhite would sell a carbide reamer that would not work with the guides they supply if reamers from other suppliers work.

In any event, I guess I'll find a local shop that can size the C630 guides. Spending $250 on a single carbide reamer that may or may not be suitable isn't worth the risk. I miss having Bill Moeller (Bore-Tech) a short drive away.

Thanks, Ken and Jim.

For those who might be wondering, C630 (or C63000) is also known as Ampco 45, AMS 4640, ASME SB150, ASTM B150/B150M, ASTM B124/B124M, SAE J461; SAE J463, and has been popular of high performance valve guides for several decades, at least.

Ken

lcrken said:

For those who might be wondering, C630 (or C63000) is also known as Ampco 45, AMS 4640, ASME SB150, ASTM B150/B150M, ASTM B124/B124M, SAE J461; SAE J463, and has been popular of high performance valve guides for several decades, at least.

Ken

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