L92 valve guide cracked, need insight

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Oct 27, 2013 | 06:06 PM

schreurs1

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L92 valve guide cracked, need insight

Just bought an L92 for my fox. Motor is a core that broke a valve spring, bent a valve and pushrod, broke the lifter and tray and scuffed the piston. Piston looks ok but when the valve bent, it cracked the guide and put a hairline crack in the surrounding aluminum. My question is what should a guy do with that crack? Weld it? Leave it? Machine the guide support out completely? On our aluminum headed sprint car engines, the guides have no surrounding aluminum support where the guide enters the runner so that makes me wonder if I can't just leave it or grind it down. It's only cracked on one side so I don't think it will drop a chunk of aluminum into the motor, but I'm also not an engine builder either. So what would you do?

Oct 27, 2013 | 07:58 PM

litle88

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Pics?

Oct 28, 2013 | 01:20 PM

schreurs1

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Here is a pic of the guide. Obviously the guide itself will need to be replaced. To left of the guide is the hairline crack in the casting.

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L92 valve guide cracked, need insight-guid2.jpg

Oct 28, 2013 | 01:25 PM

schreurs1

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will try to get a better picture tonight

Oct 28, 2013 | 01:49 PM

1989GTA

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Welding is an option. However you just might be better off buying a new head. Will wait for a better picture.

Oct 28, 2013 | 04:55 PM

schreurs1

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Oct 28, 2013 | 04:56 PM

schreurs1

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Our ASCS engines don't have the aluminum where the crack is, just a guide hangin out in the runner. And that's a lot more abusive environment as well.

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Oct 30, 2013 | 10:51 AM

KCS

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From: Conroe, TX

I'd pop the guide out and then take a look.

If it isn't too bad, you may be able to just grind it out and keep material removal to a minimum to keep the crack from spreading further. If it gets to where you have to weld and then remachine the guide boss, it may be more cost effective to find another head and chalk this one up as a practice or mock up head.