Missing Valve seat
 

A little history first. I have a 28 Tudor that I bought from my parents. The car was originally bought by my great grandfather new in 28’, so it’s really cool that it has never left my family. I’ve had it for about 14 years and so far replaced the full braking system, steering and re-wired it front to back. Few other odds and ends as well as required. Fun Sunday driver and ice cream getter but not a ton of miles over the last few years. I had it out in the fall and she started backfiring badly and just running poorly. Changed the point and condenser on the side of the road, no change so limped her home on edge of the road. After some talking with the financial dept (wife), we decided to pull the motor and rebuild the transmission and replace the clutch as they both needed it, and give the engine a good inspection while it was out and on the stand. The engine has been rebuilt before (~40yrs ago), so I expected some wear and tear and figured I had some sticky valves etc causing the backfire. Pulled the mains and found some cracked babbit, but not terrible. Very little wear and 0.002-0.003” clearance. Cylinders measured out at 0.065” over, in very good condition, no scoring or upper ridge. What shocked me were the valves. One hardened seat is loose and one is missing altogether. No evidence in the cylinder of broken pieces, nothing stuck in the exhaust port. It’s just gone! Has anyone seen this before?
Either way, we are getting a full rebuild. Give the old girl a new heart. I’ve just never seen that before.

Re: Missing Valve seat
 

look in your exhaust pipe or muffler could be there.

Re: Missing Valve seat
 

Well I figured broke into multiple pcs and went out the exhaust. Thankfully didn’t get into the cylinder bore

Re: Missing Valve seat
 

I think you're correct there. It would be impossible for it to go out the exhaust in one piece. I've just said in another thread that I have never installed hardened valve seats and don't think I ever will. This is one reason why. IMO, you won't be able to put another seat in those recesses, they will have to be machined even larger, leaving even less of the good original cast iron (another reason I don't do it) and I'm not even sure suitable new seats are available. I hope you don't have to rebuild a different block.
Please keep us informed on how you go with it.

Re: Missing Valve seat
 

I don't think these were hard seats, but cast seats, same as the block.

No, you can't use the same size, but they have all kinds of thickness, and diameters.


Herm.

Re: Missing Valve seat
 

Stellite seats come in all sorts of diameters and thickness can be adjusted if needed. I've seen the original seats crumbling to pieces when disassembling the engines. I'm not sure if Ford used any in the model A era unless it was for repair of worn pockets. I think Ford started using them around 1935 for the V8 engines. They have long been used for repair purposes.

Seat inserts coming loose is not real common but it does happen. They have to be a tight fit with good quality tooling for the counterbore process to get them right.

Re: Missing Valve seat
 

I had one disintegrate and end up in a totally different cylinder:confused:. Mine just sounded like a huge rattle can. It looked like yours does, where the valve sort of sinks down a bit more but otherwise looked normal. And welcome to the club.







Mike

Re: Missing Valve seat
 

That's the good news for the OP.

Re: Missing Valve seat
 

If you do it right they will stay in place. But I would never use them unless I had to. I never had one come loose. But I have fixed a few other people have done.

Re: Missing Valve seat
 

The Green books shows valve seat inserts for as early as the 33 100HP engine. Seems to me I was told there were some factory A or B blocks that had insert exhaust seats?

Re: Missing Valve seat
 

I also found a dropped valve head in another cylinder. Not model "A".

Re: Missing Valve seat
 

Ford used them for repair on all the early motors so they had them in the parts books. Ford even repaired engines at the factory to correct manufacturing irregularities. They may have used them in 1933 but I can't find information to support that. The V8 was still going through a lot of changes to correct problems.

Re: Missing Valve seat
 

Could you explain the correct way to make them stay in place, for us that have the tools and are trying to learn. I am not running a business, just do a engine now and then in my hobby shop
I have some blocks that have very large and deep rust pits that will not clean up with grinding. I have a complete Kwik-Way valve seat installation set but have not used it yet

Re: Missing Valve seat
 

They have to be an interference fit by 3 to 5 thousandths depending on size. They are installed by sweating them in. Heat the block & freeze the seat to get it started. They will generally drop right in if the temps are right. Dry ice is the best way to freeze them.

This link is about heads but there isn't a lot of difference except the block is more troublesome to heat up than a cylinder head is.
https://www.aa1car.com/library/ar993.htm

Re: Missing Valve seat
 

Rotor Wrench perry much has it covered.

Re: Missing Valve seat
 

I did have the same problem ,the engine would run on four and then three now and again .I guess the seat was sometimes in position enough for some compression . Finally would only run on three . Pulled the head and no seat apart from one piece stuck in a piston top this caused a nasty knock as the piece hit the cylinder head . Froze a new seat and heated the seat area and drove it in with a suitable socket as a driver once you start whacking dont stop !!!

John in cool lots of rain Chandler Arizona maybe sunny tomorrow !!!

Re: Missing Valve seat
 

I agree, and it's amazing the number of people that think they know how to install valve seats, but don't do it correctly. In the 80's I worked in a shop doing engine work, and I always used a liquid locking fluid on the seats, and I also peened the metal over the outer top edge of the seat to make sure they stayed locked in place.

Re: Missing Valve seat
 

yes I put a chamfer on the seat then roll metal from the block on the chamfer. I used a black fluid in my Dads garage, but I do not know where he got it from.

Re: Missing Valve seat
 

Peening should not be necessary if the fit is correct. It can still get loose when it's peened in but it will move around in the pocket and just get more fretted and loose. This is why the interference fit has to be so tight. Cast iron is easy compared to aluminum though.

When I was first getting into aircraft engine overhaul, we had a local shop that would rework the cylinders for us. This work was carried out with the aluminum head still on the cylinder. There were generally always cracks in the head that had to be welded up first. If a crack was in a place that couldn't be welded, they scrapped the cylinder. Welding would include repair of either or both spark plug bosses, valve seat pockets, and dome cracks. Machining was performed after all the welding was done to get fits for all affected repairs so that the inside of the combustion chamber looked like new. The cylinder bores were then plated and processed for piston fit. The valve guides and seats were then installed. They had to be tight due to the large size of the valves. The valves guides were were then reamed to size and the valves were seated and blued for proper seal on the valve faces. Rocker shaft bushings were replaced and fit to size to finish the process.

With all this work, we still could have problems with seats coming loose but it thankfully wasn't too often. All this process was eventually changed to improve the repaired product. This included unscrewing the head from the barrel so that repairs could be performed and the head could then be re-heat treated to relieve stresses. It made it easy to install the new seats too. New barrels were screwed on to make a much more reliable repair. The company started manufacturing their own cylinders since they had this capability under and FAA parts manufacturing approval (PMA). The reason they did this was that it was cheaper to make a new cylinder than it was to do all the repairs. We still had to have our oddball helicopter engine cylinders overhauled in this fashion since they didn't make new replacements for those.

Long story short is the company was bought out by Contenintal Engine Co for its PMA business and FAA approved processes then shut down and sold off. So now Continental is heavy into the Lycoming engine parts business and we have to buy the new oddball helicopter engine cylinders from Lycoming. So much for progress. It's just too expensive to carry the product liability for repaired parts now days.

Re: Missing Valve seat
 

Diamond A and B blocks had seat inserts on the exhausts from the factory.