The Ford Barn

Bud BC · 03-26-2012, 11:23 AM

One of the exhaust valve seats is mildly messed up, there appears to be less than a necessity for a new seat installation but more than a simple lapping can correct. I am wondering if there is a direct replacement valve available that has a slightly larger diameter head but will have all the same stem size/length as the original. Thanks for any info.

1928Pickuppain · 03-26-2012, 12:40 PM

Is it that the valve seat is scored a little deep than a lapping would be able to resuface?

Patrick L. · 03-26-2012, 02:32 PM

I think the seat would have to be really bad that it couldn't be re-cut or ground to place the contact area where it needs to be.. If the seat can be cut so the contact area doesn't run off the valve face and is .080"-.090" wide you'll be fine.. If the valve can be re-faced so there is still a good margin and isn't too loose in the guide it'll be fine..

Bud BC · 03-26-2012, 03:22 PM

I suppose my first step should be to do a thorough lapping job and see whats what. I wanted to be prepared with a slightly bigger valve just in case. Thanks for the response.

James Rogers · 03-26-2012, 05:25 PM

Quote:

Originally Posted by Bud BC

One of the exhaust valve seats is mildly messed up, there appears to be less than a necessity for a new seat installation but more than a simple lapping can correct. I am wondering if there is a direct replacement valve available that has a slightly larger diameter head but will have all the same stem size/length as the original. Thanks for any info.

To answer your question, if you are using the old style mushroom valves, no. You might find a modern style that is slightly larger but probably not. You probably need to just have the seat cut slightly and the valve faced and put it back together. That is how most modern engines are repaired. Beside this, you would be better off to find someone who can put a seat in without tearing the engine down. I do seats like that all the time. I use a KO Lee knockout tool to cut the seat and drive the seat in, recut the seat to the valve and I am done.

columbiA · 03-26-2012, 08:26 PM

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I would find some one with a portable seat grinder & they can do the job in a matter of minutes.For me,the seat would have to be very bad before I would resort to installing an insert.I have seen numerous engines where the seats have have come loose.Obviously,if the job is done properly,they should never loosen,but why take the chance.As for installing hard seats for unleaded gas,thats a crock of BS.These are low speed ,low comp engines that ran on unleaded when new.

Patrick L. · 03-27-2012, 08:05 AM

It appears Bud has his heart set on lapping that valve.. If he completely spins that valve he'll see a full compound lap ring and think the problem is fixed..

03-26-2012, 11:23 AM	#1
Bud BC Junior Member Join Date: May 2010 Location: Surrey, British Columbia Posts: 13	Replacement oversize valve? One of the exhaust valve seats is mildly messed up, there appears to be less than a necessity for a new seat installation but more than a simple lapping can correct. I am wondering if there is a direct replacement valve available that has a slightly larger diameter head but will have all the same stem size/length as the original. Thanks for any info.

03-26-2012, 12:40 PM	#2
1928Pickuppain Senior Member Join Date: May 2010 Location: Billerica, Ma Posts: 461	Re: Replacement oversize valve? Is it that the valve seat is scored a little deep than a lapping would be able to resuface?

03-26-2012, 02:32 PM	#3
Patrick L. Senior Member Join Date: May 2010 Location: Largo Florida Posts: 7,225	Re: Replacement oversize valve? I think the seat would have to be really bad that it couldn't be re-cut or ground to place the contact area where it needs to be.. If the seat can be cut so the contact area doesn't run off the valve face and is .080"-.090" wide you'll be fine.. If the valve can be re-faced so there is still a good margin and isn't too loose in the guide it'll be fine..

03-26-2012, 03:22 PM	#4
Bud BC Junior Member Join Date: May 2010 Location: Surrey, British Columbia Posts: 13	Re: Replacement oversize valve? I suppose my first step should be to do a thorough lapping job and see whats what. I wanted to be prepared with a slightly bigger valve just in case. Thanks for the response.

03-26-2012, 08:26 PM	#6
columbiA Senior Member Join Date: Nov 2011 Location: B.C. Canada Posts: 1,746	Re: Replacement oversize valve? Sponsored Links (Register now to hide all advertisements) I would find some one with a portable seat grinder & they can do the job in a matter of minutes.For me,the seat would have to be very bad before I would resort to installing an insert.I have seen numerous engines where the seats have have come loose.Obviously,if the job is done properly,they should never loosen,but why take the chance.As for installing hard seats for unleaded gas,thats a crock of BS.These are low speed ,low comp engines that ran on unleaded when new.

03-27-2012, 08:05 AM	#7
Patrick L. Senior Member Join Date: May 2010 Location: Largo Florida Posts: 7,225	Re: Replacement oversize valve? It appears Bud has his heart set on lapping that valve.. If he completely spins that valve he'll see a full compound lap ring and think the problem is fixed..