Valve seat issue

Ralph Moore

Ralph Moore

Well-known member
This is the problem I spoke of on th "29A rods" thread.
The pics are not too clear, but in the second you can see the seat has been peened in, and there is some of the block surface damaged to the left of the seat. Additionally the surface machining took a small amount of material from the top portion of most of the valve seats on that side of the block. It's not into the seat face, but it appears the block face was not level when cut.
Can this be run as is, or can it be saved, or have I got an expensive coffee table stand?

Thanks,

Ralph
 

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It is normal for that side of the block to expose the seat ring so when a deck cut is made it will machine the upper edge of seat ring. There was probably no error in the machine set-up.

Because that is an exhaust seat, and subject to much more temperature differential than an intake seat, I would not use it without adding a couple of "dutchman" screws to be absolutely certain the ring will stay in place. The alternative would be to install a new, larger diameter seat ring.
 
I'm not familar with the dutchman screws your talking of. Will the machine shop know or can I install them myself?
 
Take a small hammer and tap the inside of the seat... You don't want to hear a dull thunck... Tap a couple of the others, compare the sound... You're looking for a loose seat... If you find one, I would remove it. The seats need to be tight for the heat exchange (no offence) I would not want screws holding my seats in... Speedway, and probably others makes an oversize seat- these can be cut in a lathe to fit the size hole that you have without machining the block to fit the seat... Feel free to contact... Karl
 
Can the area where the block is dinged be welded up and then machined? Living where I do, I have very limited sources for machine shops, but there are plenty of guys that are into old fords.
 
That seat area has always been a problem area for cracks when the operatring temps get too high. All those peened areas set up stress risers where a crack could start. Cast can be welded sucessfully but it has to be done by a specialist in that field. The block has to be heated to weld and then cooled down very slowly. Bad welds can cause even worse crack problems than an overheated block. A new oversized seat will need a nice strait bore to go into so a machine shop with this capability is a must. It may work OK even if some of the peen marks are still there as long as they a smoothed around any sharp edges.

Kerby
 
Welding and remachining is not necessary. However, if you have acces to someone who can "machine" after welded they can certainly machine, without welding, slightly oversize to accomodate a new seat ring. Using a slightly larger ring in the existing counterbore is probably a bad idea. It would be a very welcome surprise to find it to be round and smooth after the old ring is removed.
 
I had one similar to that in an old 21stud motor. The marks at the side of the seat are made by a previous seat when it popped out and wedged between the valve and the block.
In my case the seat popped out again and I was able to successfully remachine the block to accept a (factory supplied) oversize seat.
I didn't peen it like that and it was in a stock small displacement motor and it was a good serviceable repair.
Mart.
 
That makes sense that those marks were caused by a popped out seat. I was planning on running this motor in my 30 coupe. Isky cam and dual carbs, lake pipes, but mostly stock other than that. I have other motors I can use, but none are as far along as this one.
 
I understand Karl's concern for a loose exhaust seat regarding poor heat conduction, but I believe JWL's solution of "dutchmen" screws to be OK if seat is not excessively loose - when the seat begins to heat, it will expand and tighten sufficiently to work properly, IMHO.....Bob L
 
Yes, the screws work just fine. I am aware of a couple of engines still running, after many years, with an "emergency" seat repair done while engine was in the car. But why argue? Just offer correct information and let people either use it, or, ignore it.
 
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