Get new valves or lap the old ones ?

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acarlson
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Get new valves or lap the old ones ?

Unread post by acarlson » Thu Apr 27, 2017 1:01 pm

My exhaust valves have some pitting around the edges. The intakes could use a cleaning. The valve seats look like they're in pretty good shape. For a little over $200 I could put all new valves (from Clarks) in the heads. What's the opinion of the peanut gallery here ? Lap and reuse the old or replace with new ?

Alec
1965 Regal Red Corsa 4 Speed Turbo Convertible

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cnicol
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Re: Get new valves or lap the old ones ?

Unread post by cnicol » Thu Apr 27, 2017 1:40 pm

You have to measure the valve's "margin" to know if they have enough meat left for resurfacing. I don't know the spec offhand but it's something like .050". If the valve is too thin at the margin it will overheat and/or warp.
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Jerry Whitt
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Re: Get new valves or lap the old ones ?

Unread post by Jerry Whitt » Thu Apr 27, 2017 7:09 pm

Also measure valve guide inside diameter, valve stem diameter and check specs.
With valves out, you can now check valve spring pressures as well.
Are you replacing the valve stem seals?

Lapping is not considered top quality work, but that of a backyard guy trying to save a buck rather than do a really good job. After a really good machine shop has done the valve grind, they quite often will lap the valves as one of the last steps, not instead of doing good quality work.

Take the heads to a really good machine shop. Then you don't have to worry once its been reassembled.
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66vairguy
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Re: Get new valves or lap the old ones ?

Unread post by 66vairguy » Fri Apr 28, 2017 9:29 am

I don't know why, but over the decades many Corvair owners have complained that shortly after "lapping" in the valves the seat(s) would drop out.

Now it's rarely done because of the high mileage on these engines which usually means the valve guides are worn beyond specification, valve springs are weak, etc.

The Corvair, unlike most 60's domestic engines, had hardened valve seats and quality valves that are usually trouble free until they are so worn they require a complete head rebuild. The exception is overheating the head that can do severe damage. It is necessary to find a shop that specializes in Corvair heads. It won't be inexpensive!!!

Tell us what area you are in and folks can make suggestions.

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acarlson
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Re: Get new valves or lap the old ones ?

Unread post by acarlson » Fri Apr 28, 2017 10:48 am

66vairguy wrote:
Fri Apr 28, 2017 9:29 am
Tell us what area you are in and folks can make suggestions.
I live in north Georgia - in the foothills of the Appalachian Mountains. I'd like to find a shop that understands corvairs. Ted gave me a lead to some guy here. I drove out to his address - it's a house with a garage. No signage that would indicate there was a business there. I called him and left him a message. He hasn't responded. It's easy for those of you that live in a civilized part of the country but that's not north Georgia.

I don't know that I need a full valve job. I measured a few intake/exhaust valve guides & stems and they were within spec (.002 intake, .0035 exhaust). The service guys at Clarks recommended that I lap the valves - even if I get new ones. I'd like to be able to take my heads somewhere, have them double-check my measurements and tell me what is necessary rather then what would be nice to have.
1965 Regal Red Corsa 4 Speed Turbo Convertible

funvairs
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Re: Get new valves or lap the old ones ?

Unread post by funvairs » Fri Apr 28, 2017 2:23 pm

I would suggest that you drive over to the Corvair event in Helen Sat. morning. Ask around for Bill McColl or Bill Pritchet. There are probably others that could help you out.
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acarlson
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Re: Get new valves or lap the old ones ?

Unread post by acarlson » Fri Apr 28, 2017 4:33 pm

funvairs wrote:
Fri Apr 28, 2017 2:23 pm
I would suggest that you drive over to the Corvair event in Helen Sat. morning. Ask around for Bill McColl or Bill Pritchet. There are probably others that could help you out.
Actually I was there this morning. My 1st Vair fest. It was interesting - I bought some parts I needed and watched the races. I'm hoping to drive my Corsa there next year and be a participant rather then a spectator. I won't be able to return tomorrow - I'm judging a BBQ competition all day. In any case keep the suggestions coming - I appreciate all your help ! :tu:
1965 Regal Red Corsa 4 Speed Turbo Convertible

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