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New valves-what should I do ?

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kch

kch

Senior Member
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I have bought new inlet valves. The valve seats looks ok.
Should I leave the valves and top to a professional, so he can do the valve seats and inlet valve to fit together. Or can I fit the valve to the valve seat by using valve paste ?

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Hello Karl,
it is not a bad job if the seats are good, but you won't really know until you start. I suggest that you try some fine paste and see what results you get, if there are a lot of pit marks or you don't get a full circle (not so common) then it is probably better to get the seats re-cut by an engine shop. The better way of cutting the seats is to triple cut them (15, 45, 60 degree angle, assuming the standard seat is 45) which leaves a narrow seat and better gas flow into the engine.

Alec
 
It's a lot of work to get the head off the car and disassemble it. I wouldn't want to do it more often than necessary. A "professional" valve job isn't all that expensive. He will be able to re-grind the seats, check the guides for proper fit, check the springs for wear, resurface (skim) the head and make sure there are no cracks or other defects that would mean premature failure in the future.

I just had a 4 cyl redone for about $350 (ouch!), but it needed everything, including 8 springs, 8 guides, 8 valves and hardened seats as well as having about .125 taken off the face to raise the compression ratio. Hopefully your head isn't that bad.
 
[ QUOTE ]
I have bought new inlet valves. The valve seats looks ok.
Should I leave the valves and top to a professional, so he can do the valve seats and inlet valve to fit together. Or can I fit the valve to the valve seat by using valve paste ?

/ubbthreads/images/graemlins/cheers.gif

[/ QUOTE ]
Karl, I hope you plan on replacing the exhaust valves as well. Usually they are worse off than the inlet valves. It can be done at home but if you need to have the guides replaced better to leave to the pros. A quick check of the guides is to try and move the valves sideways, (without the springs in place of course), there should be no movement.
 
The exhaust valves looks ok. I am replacing the inlet valves because they were not pretty at the bottom end. The camshaft chain was offset by to theeths when I took the engine apart, so there was a lot of carbon around inside the top.
When I am looking at the AH-spares parts catalouge, there is a part that they call: oil seal-valve stem, it is a rubber o-ring. It is palced on top of the valve. This part was not on my valves, but there is nylon caps on top of the valve guide. Anybody knows what the oil seal-valve stem (rubber o-ring) is good for ?
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The little rubber "O" rings were the original oil seals for the valves and perform that function very well. I have not seen the Nylon type you mentioned.--FWIW---Keoke PS Get a Pro to do the Head.
 
The fuel type I use is all unleaded, but I fill they tank up on HydroTexaco stations, they deliver fuel with lead substitute. But fewer and fewer stations deliver this kind of fuel as most cars use unleaded fuel. So when the fuel with the lead substitute goes out of the market I have to put lead additives when tanking. It is possible to put in valve seats in the top so the car can run on unleaded, but I am not going to do that job now. /ubbthreads/images/graemlins/thirsty.gif
 
I think that the myth that unleaded fuel requires special valve seats was & is promoted by the people who stand to gain from it. Sellers of fuel additives & machine shops. The truth is, leaded fuel is not needed to protect valve seats from lack of lead, nor are additives. It seems like anytime there is valve trouble on older engines, it will be blamed on unleaded fuel. For the average non endurance racing engine there is rarely a valve problem which can be attributed to non leaded fuel. But with the promotion by special interest groups & the need to blame "something" for valve failure, unleaded gets the blame.

Below is a partial quote taken from "Carolina Triumphs" on the subject. There are more from other credible & independent sources but this one sums it up well:



"AMOCO OIL COMPANY

PRODUCT INFORMATION

SHEET #PI 299A

Does Use of Lead-Free Gasoline Cause Valve Problems?"

" We occasionally hear comments that using lead-free gasoline will cause valve problems in older model cars. We do not believe there is any practical basis for this claim.

When use of leaded gasoline began in the 1930s, carmakers experienced serious problems with burning of exhaust valves. Lead deposits would accumulate between the valve face and seat and prevent the valve from closing tightly on its seat. Cracks or "gutters" would form in the lead deposits, which made the valve leak, overheat, and burn. After considerable development, carmakers alleviated the problem by redesigning engines with sharper valve seat and face angles, narrow seat widths and higher value spring forces, and Induced or forced rotation of the valves. These changes increased the contact pressure between the valve and seat, and caused the valve to grind out offending lead deposits. Even so, value burning continued to be a chronic, but minor, problem with leaded gasoline.

These measures to eliminate valve burning are unnecessary with lead-free gasoline. Under normal operating conditions, an engine designed to tolerate leaded gasoline will run without any difficulty on lead-free gasoline. It IS possible to fail exhaust valves in laboratory engines operated on dynamometers by running them CONTINUOUSLY AT VERY HIGH SPEED AND POWER OUTPUT. Without the lead deposits present, the valves may wear or "recess" excessively into the softer seats. However, the conditions necessary to cause value recession do not occur in normal driving, and can be attained only under HIGHLY UNUSUAL (and generally illegal) driving. Most people could not drive that way even if they wanted to.

All passenger car engines built after 1974 and most engines built after 1971 have hardened valve seats, and valve distress cannot be induced in these engines even in dynamometer tests. Most commercial gasoline engines are equipped with hardened valve seat inserts, which prevent distress under any type of operation.

We, of course, have marketed lead-free gasoline in the eastern and southern states for over 70 years. Our customers have driven millions of miles using this gasoline in all types of cars without valve problems. We think our long field experience conclusively demonstrates that lead-free gasoline does not cause valve problems."
D
 
I am not so sure Dave, after all KCH will tell you AMOCO was one of the manufactures of the LRP he now losing. It has been available through out Europe. Further, there exists an equal number of experts on the other side of the fence.--FWIW--Keoke /ubbthreads/images/graemlins/confused.gif
 
ThomP, why did you replace the valve seats with hardened ones were the original seats pitted? Just curios,Mine were.---Keoke
 
"Further, there exists an equal number of experts on the other side of the fence.--FWIW--Keoke"

Keoke,
FWIW, here is another supporting report. I think John Mitchell should be credible. I believe similar tests were run in Canada also, with similar conclusions.
https://www.vtr.org/maintain/valve-seats.html

As far as my personal experience, I have never had a valve failure attributable to not using lead, even on new cast iron seats with no inserts & a 174 BHP/liter engine. Maybe I just didn't run it hard enough for long enough?

I think that AMOCO would sell anything that they could, regardless of the non benefits to the consumer. I doubt if they are withdrawing it voluntarily if there is still a good market for it. I suspect that LRP was more of a marketing ploy than a necessity. "If a person thinks that something is true, than it "is" true for them". "Preception IS reality".

I guess we could argue this all week without a definite conclusion. If there are an equal number on each side of the fence, maybe there really cannot be a single answer. I'm just pointing out the "other side of the story".
D
 
Hello Dave,
the view that you have outlined and the information from the AMOCO OIL COMPANY does seem at odds to the general consensus in the U.K.. I think that the apparent difference can be put down, at least in part, to different driving environments and relative engine sizes.
U.K. road speeds tend to be higher, (unless your speed limits have altered greatly) and smaller engines are working harder for that speed.
With the advent of the restriction to leaded fuel, one of our respected car clubs commissioned an engine laboratory to carry out tests and invited all manufacturers of additives that claimed to reduce valve seat recession to submit them for testing. The engine tested was the British Leyland 'A' series engine and severe recession was recorded using only unleaded fuel. I don't believe that they were run at maximum speed as AMOCO infer other tests were carried out.

For my part I run a 1968 Triumph 2.5 injected car (UK spec TR5 engine) every day and run it on one of the approved additives. My normal cruising speed is at 3,500 to 4,000 rpm and I regularly use over 5,000rpm in the gears.
Again U.K. general opinion is that unleaded and unmodified seats are acceptable if engine speed is kept below 3,000 rpm.
Personally I am happy to use the additive which is, relative to our fuel costs (approx = $5 per U.S. gallon), quite cheap.
To sum up, I think driving style has a big influence (which, to be fair AMOCO state, their driving style being rather conservative, I think) and I would not spend money doing a head rework to unleaded specification until it was worn out.

Alec
 
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