Valve Job Blues

[mrraford]

Ok, some advice please. I'm rehabbing an A engine to use as a spare (aka it's too cold to work on anything else) and in addition to the other repairs this guy needs a valve job. I've got all the necessary parts and supplies but during the clean up I've discovered that one of the exhaust valve seats is so burned up that it is not going to clean up with normal seat tools. I'm going to have to take it in for a machine shop to put in a new valve seat ring.
Who has experience with replacing one valve seat? Should I expect it to run with this repair or would I be better served to spend the money to replace all of the valve seats? Your thoughts please!

[700rpm]

Spend the money, replace the exhaust seats. You'll be glad later on. If your intakes are OK as is, no need to reseat them.

[mkmskm]

I would replace them all with the new hardened seats. That is what I did with the engine I rebuilt, and they parts and dirt cheap and the machine shop costs weren't bad either. You know you are set for a long time then.

[TinCup]

Yes you could just do one but better to do all the exhaust seats. The hardened seats are not that much and most machine shops will charge 20-30 bucks per seat.

[Vic in E-TN]

My philosophy (Henry Ford's also) - If a part is not needed, it should not be on the car. I have a few engines with hard exhaust seats and regular intake seats. I know of one intake seat that broke loose and caused trouble about 10 years ago.
Vic

[George Miller]

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Originally Posted by mrraford

Ok, some advice please. I'm rehabbing an A engine to use as a spare (aka it's too cold to work on anything else) and in addition to the other repairs this guy needs a valve job. I've got all the necessary parts and supplies but during the clean up I've discovered that one of the exhaust valve seats is so burned up that it is not going to clean up with normal seat tools. I'm going to have to take it in for a machine shop to put in a new valve seat ring.
Who has experience with replacing one valve seat? Should I expect it to run with this repair or would I be better served to spend the money to replace all of the valve seats? Your thoughts please!

It is hard to say with out seeing the rest of the seats. But remember they all went the same distance.

[Kohnke Rebabbitting]

Valve seats should always be replaced "If" you want an engine to run as good as it is capable of.

Seats that are ground down in, will not let the EX. valves run as cool as they can, and is often over looked as causing a heating problem.

Intake valve seats should be replaced, as the intake valves should all be setting on top of the block surface, the same as the EX. Valves.

Also, if you have valve seats, and there valves in various heights off the top of the block, you will get various Gas charges in each cylinder, and will give you an out of balance effect.

[Dave in MN]

Herman Kohnke is right about the proper valve placement or height being important. If you decide to install new valves...An option to installing intake valve seats would be to install larger (or up to 1.73") intake valves. The machining required at the block for most larger valves will get you into fresh metal so you would not need hardened seats to raise the valve to proper height. I install larger intake valves almost all the time on rebuilds. I've installed close to 70 sets. The 1.73" valves are available from Antique Engine Rebuilding in Skokie IL. Do a search on his business name if you want to study them. I suggest the one piece guides also...I believe/find they center the valve to the seats machining more closely. If you do install the 1.73" valves make sure you have adequate clearance to the sidewalls of the combustion chambers. An original Ford head has always worked with the larger valves but the later production heads will sometimes need clearancing. If you find the head has a "date tag" on the casting watch out...check it for clearance before installing the head! It is easy to clearance the chamber with a die grinder and carbide burr. Snyder's HC heads work with no modifications.
UPDATE: When the 1.73" valves are installed, I open up the intake port below the valve seat and blend the bottom to smooth out the transition. I find the larger valves add 1-2 HP in the dyno tests I have completed...even more when using an enlarged A manifold (or B manifold) with a "B" carb. The extra HP is only evident at the higher rpm portions of the tests. (2000-2400)
Good Day!
Dave in MN
www.durableperformance.net

[dumb person]

If the valve seat was replaced with an insert in the past it will be easy i guess. Never had to cut a seat for an insert myself. Did replace an insert once, bought a replacement one that was almost the right size, it was about 15thou' too big. Somebody had a lathe so i turned it down about 7thousandths and knew this girl who was a nurse at the surgery with access to liquid nitrogen so i took a thermos with the valve seat in the bottom to her & she gave it back to me with cold gas boiling in it. Dropped it in the hole & beat it in with a piece of wood & a hammer. Worked well.

[Purdy Swoft]

I would just replace the bad valve seat. Replacement valve seats have been known to come loose. Though it will work to save an engine, replacement seats are not part of the block and won't cool the valves as well as the original seat that was part of the block. Dave makes a good point about replacing the valves with larger modern valves with one piece guides. I got a set of modern valves that the head of the valve was about .060 larger than the original valves. With the larger valve, we was able to grind the seats enough to hit good metal.

[Kohnke Rebabbitting]

If seats were replaced for valves that are larger by .125, minus .010 wall, the under side of the ports will be uneven to catch carbon, and disrupt smooth air flow. It will not bring any more power, as by putting in a larger door, the hallway remains the same. I am not see any advantage's.

Seats do not come out if installed by a compentent machinest, and yes, never a one in 45 years, have we had come out.

Saying that valve seats won't cool the block, is just plain not true!

The fact is cast iron is soft, and it burns easy, if the valve burns, after that, it always starts burning the seat. and cast Hammers easy, and widens out, to the extent that it will not cut through all the carbon if the valve burns, or with something in is seat wear it will not close tight.

On a new rebuild, with cast iron seats, at some point in the motors life, before it is used up, the valves will have to be ground more then once.

You had to grind Model T valves, about every 3 months, when two piece valves were used. On a Model A's that pulled, or in trucks, grinding valves were common. Ford flat head V-8 motors in trucks, grinding valves every 6 mouths, to two years, hard seats, and S. Steel valves eliminated that.

The fact is, Hard Seats, and S.Steel valves, will last the life of the motor, so what you save now will be eaten up later, not even counting the aggravation!

[Purdy Swoft]

Herm, I've got to dissagree. People have been using larger intake valves for more performance for ages. Slightly larger valves have also been used so that burned seats, intake or exhaust could be ground enough to reach good metal. With a little work with a die grinder, the underside of the ports can be enlarged to match the bottom of the seat. I do port work on my modified model A engines and it certainly does make a difference in performance. This sort of thing has been performed since before either of us were born. If you can't see an advantage, you are just making it obvious what you don't know.

I have no doubt that you can properly install valve seats. There are lots of people that can't properly install valve seats. Good automotive machine shops are getting few and FAR between, model A owner beware. This is not a pissing contest. I'm not in competition with anyone here,I only do my own engines and i'm not new to model A's.

I didn't say that valve seats cool the block!! I said that replacement valve seats are not part of the block and don't cool the valve the same as the original seat that vas part of the block. Cylinder sleeves, valve seats and spark plug adapters don't transfer the heat to the water jacket the same as the original parts that were one and the same as the block and head. Thats not saying that sleeves, valve seats and spark plug adapters won't work, its just a last resort to save an engine and it will effect engine temps. The valves cool while they are on the seat, even a few thousants of of lash will make a big difference in cooling the valve. If the seat doesn't transfer the heat the same as original , you will be faced with the aggravation of a valve job much quicker.

I agree that cast iron is softer than some grades of stainless or even carbon steel. The word is that the gas , back in the day didn't didn't have tetraethyl lead until 1931.Most model A's had to run unleaded gas . It is also known that model A's don't have to have hardened valve seats. I've got lots of core engines and none of them have hammered out valve seats like you describe. I've still got my first model A engine and I have only needed to cut the valve seats once in over 50 years. Nothing That I have said here is new or unheard of. Find sombody else to pick on.

[BILL WILLIAMSON]

Herm, my man,
Just remember, some of the statements that get you ROWED UP are just "HERESAY" STUFF! LOL! Take it with 7 grains of SALT. Bill W.

[Jerry Parr WI]

Having had two seats come out of a rebuild (well known rebuilder) I decided I would only replace bad seats in the future. These were replaced solely because hardened seats are "better". If they are bad then no choice but no need to create possible failures.

[bbrocksr]

Herm is right ,Insert seats/hard seats are far superior to cast iron seats. They will take more heat/abuse than a cast iron seats. That's why they are used in almost everything that is high performance or heavy duty.
Such as Truck engines,diesel engines, race engines, aircraft engines and if their put in right they don't come out.
If they come out they weren't put in right,pretty simple.

A stainless valve and a properly installed hard seat will take a lot more heat/abuse an last far longer than a stock valve on a cast iron seat.
Bill

[columbiA]

Many years ago,When I installed inserts on engines converte to propane,I would smear a mixture of Litharge & Glycerine around the cut seat & shrink the new hard seat with a CO2 extinguisher & drive them in.

[bbrocksr]

Originally Posted by columbiA

Many years ago,When I installed inserts on engines converte to propane,I would smear a mixture of Litharge & Glycerine around the cut seat & shrink the new hard seat with a CO2 extinguisher & drive them in.

Used the same thing on the sleeves.
Bill

[Kohnke Rebabbitting]

I didn't say that valve seats cool the block!! "END QUOTE"

No, you said:


replacement seats are not part of the block and won't cool the valves as well as the original seat that was part of the block."END QUOTE"

Still not true.

People have been using larger intake valves for more performance for ages. Slightly larger valves have also been used so that burned seats, intake or exhaust could be ground enough to reach good metal. With a little work with a die grinder, the underside of the ports can be enlarged to match the bottom of the seat."END QUOTE"

Ya, you can do that, but why butcher an engine. Yes you can port, and even put on an over head valve head, so what, the post was about a valve job.

I have yet to see any Model A valve seat that was to far gone for a hard seat.

It is also known that model A's don't have to have hardened valve seats. I've got lots of core engines and none of them have hammered out valve seats like you describe."END QUOTE"

No, A's and most others don't have to have hard seats, you can use the block, BUT, they will not out last an engine rebuild. Just like what Mrraford needs now. If you haven't seen hammered Model A valve seats, then you are very short on experience. A narrow cast seat, will hammer to a wider seat, that you don't find with a Hard seat.

I don't think I have seen a engine today that don't have hard seats. They seem to transfer heat real fine.

I will say again, a larger valve does you no good, when the port is made bigger, and by the time you go through all that, you could have put in seats, and valves the will last the rest of the motor. S.Steel, and hard seats, the periodic valve grinding is over.

Jerry, you can say the same thing about, babbitt, cylinder boring, piston fitting, Block surfacing, Flywheel housing mounting, Flyhweel grinding, cam bearings, Align Boring Ect.

[just plain bill]

Geez, guys, these are low power engines operating at the normal high end of 2000 to 2500 RPM's just like old or vintage tractors. I have three and the exhaust valves are running in the original cast seats. On my modified engines I have hard seats only on the exhaust valves. I don't remember regular gas being advertised as using lead, just premium grades, and the vast majority of model A's ran regular. Just too much needless reengineering going on. I have 4 or 5 A blocks and only recall 1 with a burnt seat. Hafta go look after it stops snowing.
It would seem that a properly maintained, with proper valve lash, A engine that is not a daily driver would work just fine with reground seats and next oversize valves. IMO

I guess that I'm going to feel the wrath of the model A "Gurus" coming down on me, but as Elmer Kieth said " Hell, I was there"

[BILL WILLIAMSON]

Originally Posted by just plain bill

Geez, guys, these are low power engines operating at the normal high end of 2000 to 2500 RPM's just like old or vintage tractors. I have three and the exhaust valves are running in the original cast seats. On my modified engines I have hard seats only on the exhaust valves. I don't remember regular gas being advertised as using lead, just premium grades, and the vast majority of model A's ran regular. Just too much needless reengineering going on. I have 4 or 5 A blocks and only recall 1 with a burnt seat. Hafta go look after it stops snowing.
It would seem that a properly maintained, with proper valve lash, A engine that is not a daily driver would work just fine with reground seats and next oversize valves. IMO

I guess that I'm going to feel the wrath of the model A "Gurus" coming down on me, but as Elmer Kieth said " Hell, I was there"

Bill,
Don't worry about me comin' down on you, I'm ONLY An "Assistant GURU"----With a DOG Bill W.