Head Rebuild

Butch LeBlanc · Jan 11, 2012

This head has bad valve seats, Don't know if they are inserts or not.The engine is a IH Ser# U-AA-24699 I believe it is a C123. Two of the seats are real bad.Can they be repaired or should I look for another head? I would appreciate any help.

Fritz Maurer · Jan 11, 2012

Installing valve seats is exceedingly easy. Any machine shop can do it at a modest price. Just a tip: change the guides first. This way the tooling to cut the counterbore will be concentric with the guide. Next, have the resurfacing done last, so you don't scratch the heck out of it while doing all the other work. Guides are cheap, seats are cheaper. No reason not to do both.

Fritz Maurer · Jan 11, 2012

Sand blast the valve pockets and look real close at the seat. If you are real lucky, someone else might have already installed seat inserts. If so, all you need is a narrow (1/4" max), sharp chisel driven under the insert to pry it out. Then just go to your local machinist for new inserts.

rustred · Jan 12, 2012

do as fritz says. dont you trust your machine shop? that is all machine shop work. any reputable shop experienced in head rebuilding will do it right, by replacing seats , guides, valves, and all work that goes with the job. the average person knows little about head rebuilding.

Butch LeBlanc · Jan 12, 2012

Thanks for the help. I will look into it as you sugested, (Repair Shop)Would be the best way. Thanks again, Butch

rustyfarmall · Jan 12, 2012

(quoted from post at 19:49:38 01/11/12) Sand blast the valve pockets and look real close at the seat. If you are real lucky, someone else might have already installed seat inserts. If so, all you need is a narrow (1/4" max), sharp chisel driven under the insert to pry it out. Then just go to your local machinist for new inserts.

Sandblasting a cylinder head is NOT a good idea. I speak from experience. I worked and worked to get all the sand out of it, and then took the head to the machine shop where more sand began falling out. I had to pay the machinist a little extra to wash all that sand out.

LJD · Jan 12, 2012

If it actually has seat-inserts-it's not very difficult to pull them out and press in new ones. If no inserts - you can either grind (or cut) a new seat if not too bad . . . or have a machine shop cut the head so hardened inserts can be installed. Cast-iron heads are easy. Aluminum heads usually require super-cooling the seats before installing. I use liquid nitrogen since the local cow inseminator always has some available.

If cutting or grinding seats - depth is critical on many diesels - and not so critical on many gas engines. You just have to reclaim any lost spring tension by adding shims to offset any valve depth added by redressing. Increasing valve depth takes tension off the valve springs.

As to valve guides - some are inserts and are easy to replace with a press. If not? They can be knurled and resized if not too bad - or - machined for new inserts.

Fritz Maurer · Jan 12, 2012

I didn't mean the whole frigging head!!!

Head Rebuild

Butch LeBlanc

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Fritz Maurer

Well-known Member

Fritz Maurer

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rustred

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Butch LeBlanc

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rustyfarmall

Well-known Member

LJD

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Fritz Maurer

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