Valve Seat Replacement?
- Thread starter skeeter
- Start date
glenn in camino
Well-known member
If the seats are ok, leave them alone.
If the seats are in good shape I would leave them alone. But if you want to change them, you will need a long narrow punch or chisel. Some you can go through the valve ports to dislodge. Or you can use a long narrow chisel, insert it just under the edge of the seat and pry it out. Cover the seats with a shop towel as they usually break. They can also shatter.
Mikeinnj
Well-known member
You can use the original seats which are cast in the engine block, if they are in good condition. Look for pitting of the valve seat surface and the valve face. If the seats look o.k., try "lapping" in the valves with valve lapping compound but make sure to clean out any of the abrasive material before re-assembly. Keep each valve in it's original location by marking them as you remove them, don't mix them up. If the exhaust valves look burned or badly pitted, replace them.
Here is a link to valve lapping on "you tube".
http://www.youtube.com/watch?v=Yoes08WpL4w
Some engines have the seats re-cut, with carbide cutters but requires some expertise using the right cutting tools. Eventually the valves sink so low in the seats from having been re-cut several times, that valve seat inserts becomes necessary.
New modern stainless seats can be installed by most good automotive machine shops, which will require removal of the engine from the car. If you opt for new valve seats, consider installing new one piece valve guides and valves sold by most Model A vendors.
After you lap the valves , if you have original non-adjustable lifters you will have to grind the valve stems to get the proper clearance between the stem and lifter. If you have adjustable lifters you can make the necessary adjustments.
Remember, the Model A has a low compression and you can not really do anything wrong.
I would only replace the original valves if one of these conditions have occured.
1. Bent Valve.
2. The valve stem is pitted
3. The bottom of the stem is mushroomed.
4. The valve stem is to short and you can not get the proper gap between the stem and the lifter. If you have adjustable lifters then this may not be an issue.
Here is a link to valve lapping on "you tube".
http://www.youtube.com/watch?v=Yoes08WpL4w
Some engines have the seats re-cut, with carbide cutters but requires some expertise using the right cutting tools. Eventually the valves sink so low in the seats from having been re-cut several times, that valve seat inserts becomes necessary.
New modern stainless seats can be installed by most good automotive machine shops, which will require removal of the engine from the car. If you opt for new valve seats, consider installing new one piece valve guides and valves sold by most Model A vendors.
After you lap the valves , if you have original non-adjustable lifters you will have to grind the valve stems to get the proper clearance between the stem and lifter. If you have adjustable lifters you can make the necessary adjustments.
Remember, the Model A has a low compression and you can not really do anything wrong.
I would only replace the original valves if one of these conditions have occured.
1. Bent Valve.
2. The valve stem is pitted
3. The bottom of the stem is mushroomed.
4. The valve stem is to short and you can not get the proper gap between the stem and the lifter. If you have adjustable lifters then this may not be an issue.
Last edited:
James Rogers
Well-known member
Mike, I have a KO Lee knockout and can replace seats in the car with the head off and valves out. Skeeter, if the seats look good, don't bother them. Try to have them ground just enough to smooth any imperfections and lap the new ones in and you are good togo. Any shop that can do valves probably has a grinder and the pilots to be able to touch the seats if you take the car to them. The grinder is portable.