Valve guide

[Excalibur]

Anyone seen this sort of break? I'd noticed the guide looked loose from above and after prodding and wiggling, it snapped right off. Witness marks show it was only just hanging on.
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Is it common? Perhaps from fitting guides with a drift and hammer? It does have an O-ring which means the diameter is wasted by about .080".

Other head exhaust guide is already removed but I've turned my attention to both intakes. They both look good and have satisfactory fit to valve. Am I being over cautious?

Thanks for any thoughts, tips, experience etc.

[capn]

Had one snap off exactly like that.Happened when I tried to get the seal off.It looked cracked already also.Time for a valve job.I ended up buying new Ultima heads.

[Hillside Motorcycle]

Probably fractured at the point of installation, and finally failed.
Easily repaired.

[capn]

Valves and guides are cheap.While its all apart might as well get it right.

[Excalibur]

Yeah, you're right. Pulled all guides. Bit of a can of worms. Rear exhaust had +.008" and guide hole in head is awful. Other holes are up to .0015 out-of-round, though guides were standard.
I can't remember cleaning up guide holes before but I have done numerous guide installs over the years. What's the way to get it sorted? Is it to be line reamed with a pilot true to seat?

Is fit .0015 - .0025" according to Kibblewhite the go?

Thanks for any help, tips, pointers etc.

[Don D]

I hone the holes with a Sunnen P190.

[Excalibur]

Studying the P-190, it looks like that's for doing the guides fit-to-valve clearance.? Not for sizing the hole in the head itself.??
Guide bore in head is .625" (standard) minus the interference. Old school must have a nice way of tickling a thou or two out of these holes?

[Hillside Motorcycle]

We fixture the head and then precision bore to establish a straight, round, true guide bore, and if a custom guide needs to be manufactured, that is then done as well, from guide blanks, or raw bar stock.
JUST finished that scenario for a Shovel client, from PA, including the manufacture of a valve seat for him.
Easy, peasy.

[crock]

We fixture the head and then precision bore to establish a straight, round, true guide bore, and if a custom guide needs to be manufactured, that is then done as well, from guide blanks, or raw bar stock.
JUST finished that scenario for a Shovel client, from PA, including the manufacture of a valve seat for him.
Easy, peasy.

Old school/New school. Gotta love how much easier it is to keep old iron running compared to 20 years ago

[capn]

Instead of all that machining you can buy bare heads with guides and seats from ultima.Or complete if you want.They will install a .600 lift set up for $100 extra.

[crock]

Instead of all that machining you can buy bare heads with guides and seats from ultima.Or complete if you want.They will install a .600 lift set up for $100 extra.

AWWWW Where's the fun in that