replacing valve seat in situ

D

DjNeil

Member
Hi
I've a loose valve seat in a 49 Merc flathead with 21,000 miles on it.
I presume the valve got stuck through lack of use and pulled the seat out but don't know.In my Mercury workshop manual it says you can fit a seat without tearing down the engine.You freeze the seat and,Hey presto, you pop it back in.I have doubts you can do this.Has anyone tried?
 
You need to determine why it came loose in the first place, the vavle would not pull it out. You would also need to determine how much damage the seat has to done to the block.
 
Any major supplier of parts have them, they go by size.
1 3/8x1 5/8x7/32 is what you need.
And they are on Epray to...
But first check the size if you need an oversize or have to recut it.
If its barely pressfit you can get away with peening around the seat a bit after fitting...not the way in a perfect world...but in the real world ;)
 
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that's my world,
peening beats superglue.
Will i get away with putting it in the freezer overnight before fitting
 
I've done them in place, but I also have a set of manual valve seat cutters. Most seats come uncut so you have to take care of that.

I agree that you need to know why it fell out and I'd strongly suspect a crack in the block in the seat area.
 
You should probably search out a NOS one, standard or the slight oversize Ford offered. I think most aftermarket ones will be deeper and maybe wider and will require machine work, while the Ford ones are made for field replacement. I'd suggest Joblot, but they have gone!
And...clean and examine the area carefully. A loose seat is oft the result of the dreaded valve-to-cylinder crack!
 
You have received some good advice from several people. Determine the cause of the loose seat ring and whether or not additional machining will be necessary to "hold" a new ring. In a couple of cases I have machined special OD rings, in a lathe, to fit properly in worn counterbores. Many times the block has cracked and relaxed the fit on the ring. This is not always a disaster because there are many cracked blocks running around that do not leak or cause a problem. Some very precise measuring is required. I would be totally surprised if a stock seat could be reused.
 
So here's a good example of one replaced in situ. I discovered it yesterday after I got the stuck pistons out and started on the valves. It has been run since this repair and it didn't fail. I bought the engine, an 8ba from a small time auto dismantler and he said it must have got a bit of 'moisture' in it because it was stuck. Other than that there is no history on it. I will be putting this engine together for a '47 tonner wrecker to use around the place. Of course this is the best time to fix it, but must I take it to a machine shop on the mainland? Once a block gets into one of them places, there's no place to stop. Keep? Home remedies? I embrace the shade tree mechanic era and and currently running 2 'repaired and freshened' v8s. I have never dealt with valve seats before.
 

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The engine in my avatar has all new seats. I had them made to my specifications. Took the old ones out using an arc welder and washers that just fit into the old seats- arc the washers to the seats and they almost fall out.

Measure the holes for the seats with a bore gauge and outside micrometer.

I made a driving tool from pipe parts that squared the seats to the holes. It went into the lifter bores. Drove the new seats in with a hammer.

K.O. Lee is the company that made the seats... And, it was a few years ago.

Karl
 
Remove the seat & check for cracks. If none, small punch marks around area where seat outside diameter is located, then tap seat back in place. Mark position of seat before fooling with it. Should work. I have seen it done, but not done it myself.
 
Just got in from more fussing with this block. Reamed the ridge and did a quick preliminary hone with the stone type hone. This is the engine from my 'fire in the hole ' thread. Isn't my first rodeo, just first bad valve seat. The 59ab I did last year with home made teflon buttons instead of circlips has been getting a bunch of miles on it and going strong. Now I'm going out to dinner and a movie with my wife. I really like the input, and will check back in the morning. Thanks to all of you knowledgeable folks!
 
This is a job that is best left to a qualified machine shop because of the specialized tools needed to do the job right.
The chances are extremely slim that you can put an oversize ring in the present hole and have it last very long. The ring needs 100% contact on the OD and the underside when installed and this requires the hole be re-cut oversize.
A piloted driver is required to put the ring in. The ring needs to go in straight all the way to the bottom. If it gets cocked the slightest bit and straightened it will mar the surface it bears on and will contribute to early failure. It needs to have .005 press fit. About the only way you can get it started in the hole with that much press is the piloted driver.
There is a shop in Mt Vernon that can do this bit I don't remember the name.
 
In Mt Vernon that would be Dave Tatom. He's a very good flathead rebuilder. He is a very meticulous and if I brought it to him for a valve seat he would most likely just shake his head and say the block needs to be magnafluxed and pressure tested and bored and new pistons, rods, valves, crank turned, balanced. You all know about this routine and he makes a great point. I bought the 8ba that's in this 2 ton for 500 bucks and plastigaged the bearings, which were real good, lapped the valves, installed new rings and a set of gaskets and it gets it done whenever I need it to. Ran her pretty hard this morning with some steep uphill climbs. Of course this engine didn't have that ugly valve seat. Can most any automotive machine shop do the seat? There is a shop just off the ferry where the same guy has been for 20 years. Maybe I'll call him on Monday and see what he says. .
 

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The check for cracks in the valve seat area is right on target. Fred at South Side probably has what you need. There is some kind of compound that the machine used when they put the seats in the 59L block. I seals potential leaks from a crack if it is not to bad. Otherwise the crack should be pinned by a pro.
 
GB SISSON said:
In Mt Vernon that would be Dave Tatom. He's a very good flathead rebuilder. He is a very meticulous and if I brought it to him for a valve seat he would most likely just shake his head and say the block needs to be magnafluxed and pressure tested and bored and new pistons, rods, valves, crank turned, balanced. You all know about this routine and he makes a great point. I bought the 8ba that's in this 2 ton for 500 bucks and plastigaged the bearings, which were real good, lapped the valves, installed new rings and a set of gaskets and it gets it done whenever I need it to. Ran her pretty hard this morning with some steep uphill climbs. Of course this engine didn't have that ugly valve seat. Can most any automotive machine shop do the seat? There is a shop just off the ferry where the same guy has been for 20 years. Maybe I'll call him on Monday and see what he says. .
Click to expand...

GB.... You need to put a load on it!!!!...... LOL.... Mark
 
GB SISSON said:
In Mt Vernon that would be Dave Tatom. He's a very good flathead rebuilder. He is a very meticulous and if I brought it to him for a valve seat he would most likely just shake his head and say the block needs to be magnafluxed and pressure tested and bored and new pistons, rods, valves, crank turned, balanced. You all know about this routine and he makes a great point. I bought the 8ba that's in this 2 ton for 500 bucks and plastigaged the bearings, which were real good, lapped the valves, installed new rings and a set of gaskets and it gets it done whenever I need it to. Ran her pretty hard this morning with some steep uphill climbs. Of course this engine didn't have that ugly valve seat. Can most any automotive machine shop do the seat? There is a shop just off the ferry where the same guy has been for 20 years. Maybe I'll call him on Monday and see what he says. .
Click to expand...

Well, I think if you told Dave you know me, he would either do exactly what you wanted and no more or, just throw you out....LOL
And yes, most automotive machine shops can do a valve seat ring.
 
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