When hardened valve seats production??

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nm9stheham

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When did the hardened valve seats go into production in the slant 6's? I assume around 1970/71 as no lead was becoming available then. But I am not 100% sure.

I'm asking so to know when to worry about ugrading the seats in a rebuild versus not. Tnx!
 
Many people seem worried about hardened seats. But Just for Information, my machinist with over 30 years experience, building engines told me that the originally Installed 1960's mopar seats are harder than any ford or chevy seats at the time. And, any new seats he would order for my engine today are no better than the original factory seats made back in the day. so, don't waste your money unless the seats are bad. I remember reading a mopar Direct connection magazine article in 1988 where Chrysler tested all the mopar heads, and engines regarding seat wear with unleaded fuel. The results were, on Heads run during the 60's and early 70's, that hardened seats were not necessary unless you exceeded 85% of the RPM band, 85% of the time.Personally, I have never had to put hardened seats in an original mopar engine. Chrysler did put even harder seats in later,(1972) because of Increasing emissions standards. So, if you have a bad seats, replace them, but don't make extra work for your self, Mopars are tough! In contrast,Ford didn't even put seats in their engines in those days, so I did a lot of valve jobs around 40k with them. On A side note, lead was added to prevent pre- detonation in 1914 or so, and valve lubrication was a side benefit.
 
When did the hardened valve seats go into production in the slant 6's? I assume around 1970/71 as no lead was becoming available then. But I am not 100% sure.

I'm asking so to know when to worry about ugrading the seats in a rebuild versus not. Tnx!

im thinking in 73 like the small blocks and big blocks..

i always put hardened seats in over the years. cheap insurance in my opinion...
 
When did the hardened valve seats go into production in the slant 6's? I assume around 1970/71 as no lead was becoming available then. But I am not 100% sure.

I'm asking so to know when to worry about ugrading the seats in a rebuild versus not. Tnx!
It was later than 1970/71. I think it was 1975 when catalytic converters were first widely used on automobiles. Those demanded the use of unleaded fuel.
 
I was always under the impression that Hardened seats were standard after leaded gas was no longer legal to sell which was 1974.
 
always comes in handy
 

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Leaded fuel was available until the early 80's. Lead free engines with catalytic converters began in 1975. Coincidently that was when the octane dropped, because lead was an additive to deal with the octane issue of pre-detonation for over 60 years. In 1983 regular was 94+,premium was 98. After Unleaded fuel was introduced, the average octane rating decreased. . This is obviously an unpopular concept, but old guys from the 60's know how it was. If we can pass one piece of knowledge on, it is don't believe everything you read, and The point is don't worry about it. Mopar engines were tough, and ran on unleaded better than anything out there, so Save your money for something productive. I also drive an original 69' 340 original with the X head, seven years running, with no hardened seats, just going down the road.
 
Leaded fuel was available until the early 80's. Lead free engines with catalytic converters began in 1975. About when the octane dropped, because lead was an additive to deal with the octane issue of pre-detonation for over 60 years. In 1983 regular was 94+,premium was 98. After Unleaded fuel was introduced, everything dropped. This is obviously an unpopular concept, but old guys know how it was. The point is don't worry about it. Mopar engines were tough, and run on unleaded better than anything out there. I also drive an original 340 69' original X head, seven years running, no hardened seats, just going down the road.

Maybe some, I have a pair of 440 heads, forget the casting number, but they are 213's I think? Any way The exhaust seats are beat out of both heads. Some are .250 up in the head!
 
3751213's are motorhome heads, designed for unleaded engines, motor homes mostly. If they did that, it wasn't the fuel. I am curious though, and may look them up to see why they would do that. Alcohol additive, super lean maybe?
 
If your interested this is a pretty good report on leaded fuel.


The U.S. Experience with the Phasedown of Lead in Gasoline - MIT


web.mit.edu/ckolstad/www/Newell.pdf‎
 
Thanks again, I got it. as time went by and my older cars showed no signs of damage using the unleaded fuel under normal use, it was clear that at least Chrysler products were overbuilt to the point of tolerating lead free fuel more than the competition. As a mechanic then, I noticed other brands didn't do too well. So, the 1988 article from direct connection caught my attention.
 
According to the 72 DartDemon Owner's manual, /6 engines were designed to run on unleaded fuel. (V-8s were not included). The 73 Dart Owner's manual stated that all engines were designed to run on unleaded fuel. I infer that these are the model years when hardened valve seats were installed on the various engine lines.
 
Many people seem worried about hardened seats. But Just for Information, my machinist with over 30 years experience, building engines told me that the originally Installed 1960's mopar seats are harder than any ford or chevy seats at the time. And, any new seats he would order for my engine today are no better than the original factory seats made back in the day. so, don't waste your money unless the seats are bad. I remember reading a mopar Direct connection magazine article in 1988 where Chrysler tested all the mopar heads, and engines regarding seat wear with unleaded fuel. The results were, on Heads run during the 60's and early 70's, that hardened seats were not necessary unless you exceeded 85% of the RPM band, 85% of the time.Personally, I have never had to put hardened seats in an original mopar engine. Chrysler did put even harder seats in later,(1972) because of Increasing emissions standards. So, if you have a bad seats, replace them, but don't make extra work for your self, Mopars are tough! In contrast,Ford didn't even put seats in their engines in those days, so I did a lot of valve jobs around 40k with them. On A side note, lead was added to prevent pre- detonation in 1914 or so, and valve lubrication was a side benefit.

It was in the 1920's when they started using lead in fuel....prior to that, they used Tin....but the problem with Tin, was that it didn't stay in suspension for very long.
 
According to the 72 DartDemon Owner's manual, /6 engines were designed to run on unleaded fuel. (V-8s were not included). The 73 Dart Owner's manual stated that all engines were designed to run on unleaded fuel. I infer that these are the model years when hardened valve seats were installed on the various engine lines.



Unleaded gas was 75 as that is the first year of the catylatic converter. They could have brought the hardened seats in earlier.

My dad bought a 75 Cordoba brand new and it was the first car where it had the "unleaded fuel only" sticker below the gas tank door.
 
It is my understanding that many cars prior to 1975 were produced with hardened seats since manufacturers knew the unleaded mandate was coming and those cars were going to be subject to the rigors of running with unleaded gas.

They didn't want a bad rap when those cars that were only a couple of years old started having problems due to the unleaded gas. Just my .02. Dennis
 
OPs original question: When did the hardened valve seats go into production in the slant 6's?

Answer 1972 model year.

Without a catalyst, cars with the hardened valve seats and otherwise set up for unleaded fuel, ran leaded gas with no problem. Given an steady diet of leaded gas would lead to more deposits on the plugs than a steady diet of unleaded. FWIW: Amoco made a super premium gas that was unleaded. Supposedly a "hot" batch of this stuff would have 102 octane. It was Amoco's top-of-the-line fuel and available at nearly all stations.

The unleaded fuel that was available was 87 octane (IIRC) and did not run well with performance tuned high compression engines. Furthermore when catalytic converters started appearing in 1975, engines started sounding like Hoovers on speed due to the poor catalytic converter pass-through of exhaust gas.
 
In the early 70's The Industry had to deal with two issues, lead and emissions. 60's Mopars could deal with lead free. However, adding the restrictions on emissions at the same time, with the smog controls that followed, Increased cylinder head temperatures, and lean fuel mixtures; This caused premature valve and seat wear. This is why seats were hardened starting in 1972, not the use of unleaded fuel. Older guys can tell you the common complaint with cars from 1973 thru 1985 was:" I smell rotten eggs". Or, why is my engine running at 220 degrees all the time"?
Another common complaint: why is my head cracked? Or, why is there anti-freeze all over the ground after a long day?
 
Thanks for all of the info and answers everyone. Good data.

I will add that I recall that unleaded fuel was mandated at all stations starting around '74; the addition of catalytcis followed that by a year or so. I can remember many small stations in '74 dropping leaded regular as they only had 2 pumps, and one had to be used for unleaded regular, and they saved the other one for premium.
 
also note mopar used more nickel in the blocks and heads, they don't rust up like the others do when sitting in the corner of the garage for years .this is why the seats will last longer then other brands when using unleaded.
 
also note mopar used more nickel in the blocks and heads, they don't rust up like the others do when sitting in the corner of the garage for years .this is why the seats will last longer then other brands when using unleaded.
You hit it on the head, mopars are tough, and unleaded fuel in it self didn't cause any problems. But when you add the additional issue of tightening up emissions, all the manufacturers had trouble. Mopar just had less. except 440's and the slant six. They ran hot, and cracked heads because of the lean mixtures. Long stroke engines were doomed, as running efficiently was a pipe dream. The later 440 heads are great on 60's engines because they flow more coolant, but are thinner, which to me is Irrelevant as long as the smog controls are gone. and the 60's engines ran around 190 degrees, not 215 degrees like a 74' to 78' 440 model. if I were to build a 440, I would use the 73-78 440 head in the hot climates with TTi ceramic coated headers, then Overheating issues would be history.
.
 
Alloy radiators are the way to go for hot running engines.....so much more efficient at removing heat......and shedding some weight.
 
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