Hardened valve seats for iron heads; worth it or not?

Are your heads prepared for unleaded petrol?

  • yes

    Votes: 12 60.0%
  • no

    Votes: 5 25.0%
  • don't know

    Votes: 3 15.0%

  • Total voters
    20

Gerald Morris

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Facing the eventual necessity of a valve job and head replacement, I would like to make the 915s I purchased a year ago serve. To my knowledge, these have not ever been prepared for use with unleaded petrol, and I wonder if investing in hardened valve seats for these will be warranted. (I doubt if the old 516s I currently run have ever been so prepared either.) MOST (over 90%) of my driving is urban, and even on the highway, I RARELY turn the engine over 3000 rpm.

Given such parameters, are hardened valve seats worth my while? I WOULD like these heads to serve for a long time to come, once the effort is made.
 
If the valves haven't receded into the seats by now, they will be fine for your application.

Higher spring pressure and sustained high RPM WFO operation is what will kill them.

Kevin
 
How long will you be keeping the engine? I did mine because I did not want to have the seats be a possible failure point in the future. 30 years later the engine is still doing well.
 
If this is going to be a forever car, do the hardened seats. It is true that engines that are not run hard do not see the valve seat erosion seen on ones that are run hard. I hate having to do a job over so I do the head upgrades to be done with it for good. Your machine shop can tell you how much you valve seats have eroded. If they are in pristine condition, you can probably pass on the hardened seats. You will most certainly need to install bronze valve guides as the unleaded fuels eat them up regardless of how the engine is used.

Dave
 
http://www.bacomatic.org/~dw/index.htm
If this is going to be a forever car, do the hardened seats. It is true that engines that are not run hard do not see the valve seat erosion seen on ones that are run hard. I hate having to do a job over so I do the head upgrades to be done with it for good. Your machine shop can tell you how much you valve seats have eroded. If they are in pristine condition, you can probably pass on the hardened seats. You will most certainly need to install bronze valve guides as the unleaded fuels eat them up regardless of how the engine is used.

Dave

I'm inclined to do the job. I want the stuff to last long enough to bury me. Hughes might get the job on those heads....
 
There are other anti-wear additives in gasoline other than just tetraethyl lead. Keeping the valve guide-to-valve stem clearance "in spec" is very important in keeping the valve job alive well into the future, hard seats or not. Orange silicone Chevy 454 valve seals, trimmed to Chrysler length, work well, too.

Enjoy!
CBODY67
 
They are off. They are out. I would do the hardened seats. A few years back in had two sets done. My 302 J code heads and my 390 heads. The exhaust valve seats in the 302 were receded quite a bit so all seats were replaced. The 390 seats were hardened but really only a surface harden treatment so I had them all replaced. Each head cost me $250 to do which I thought quite reasonable for all the work done.
 
They are off. They are out. I would do the hardened seats. A few years back in had two sets done. My 302 J code heads and my 390 heads. The exhaust valve seats in the 302 were receded quite a bit so all seats were replaced. The 390 seats were hardened but really only a surface harden treatment so I had them all replaced. Each head cost me $250 to do which I thought quite reasonable for all the work done.

Such is my own thinking. I'm also considering whether to enlarge the exhaust valves from 1.6" to 1.74" to lower back pressure a bit, easing the engine's breathing. I don't want a hotrod particularly, but to develop good bottom end torque; thus the closed quench heads.
 
On my *NON* running 1977 PK41 440 when I tore the engine apart before selling the engine the valve guides were very sloppy, think the car had just over 100k miles on it.
 
On my *NON* running 1977 PK41 440 when I tore the engine apart before selling the engine the valve guides were very sloppy, think the car had just over 100k miles on it.

Were those 452 heads? Mind you, I don't doubt at all that the old 516s on Mathilda's 383 need work which is why I'm upgrading these 915s.
 
Were those 452 heads? Mind you, I don't doubt at all that the old 516s on Mathilda's 383 need work which is why I'm upgrading these 915s.
When I tore that engine apart it was back in the mid 80's and I really didn't know or really care what all the numbers mean't back then. What ever was on the 1977 440 Lean Burn Cop Car Smog motor, I just tore it down to inspect it for the for sale listing, I think it had a bad cam lobe in it too. Back then in the late 70's they were still trying to perfect the UnLeaded gas additives for guide & upper cylinder lubrication as a lead replacement. I saw many heads with not many miles that the guides were toast. ie 1974 to 1980 with 60/70k+ miles tore apart in the early 80's.

.
 
When I tore that engine apart it was back in the mid 80's and I really didn't know or really care what all the numbers mean't back then. What ever was on the 1977 440 Lean Burn Cop Car Smog motor, I just tore it down to inspect it for the for sale listing, I think it had a bad cam lobe in it too. Back then in the late 70's they were still trying to perfect the UnLeaded gas additives for guide & upper cylinder lubrication as a lead replacement. I saw many heads with not many miles that the guides were toast. ie 1974 to 1980 with 60/70k+ miles tore apart in the early 80's.

.

Ah! Yes, the Great UNLeading ****** up lots of ****. I remember it well. Late 70s cars generally were lemons due to demoralized workers, penny pinching accountants over-ruling engineers, proboematic design, doped to the gills workers on the line, bribed union stewards, and Carter's "malaise" pervading all the Good Old Stuff. Even as a teenager then, I KNEW the stuff from the mid 1960s was the Best There Ever Was.
 
Granted, by the middle 1960s, almost ALL vehicle systems had plateaued majorly. USA factory a/c systems were the world standard (especially the GMs with the A-6 compressor), power brakes were very good for everybody, the three-speed automatics were also world standard, and engineering was generally good (with, of course, Chrysler being to the highest degree of execution, with GMs being good but with the last cent wrung out of the end product, and Ford being reliable with stamina . . . EACH with their own high points in the world-wide industry). AND "brand identity" went far farther than just the grille emblem, by observation . . . getting into materials used, how the whole vehicle "felt" as you drove it, with brand loyalty still being at play.

Growing up in that time frame was great for a car enthusiast as each year brought new models and innovations. When "show date" season was something to look forward to, after reading about what might be in the many car magazines of the time.

What is now termed "the malaise era" was when "safety" became more important than "power", as exhaust emissions reduction was in the mix too. The investments in those areas, by the OEMs, took a good bit out of the prior excitement, but NOT all of it. Then came FWD! As GM and Ford downsized their models, Chrysler was the only company that still had some semblance or "performance" in their products, even the smaller FWD cars. North Loop Dodge in Fort Worth had a Dodge Shadow laid on its side in its showroom. I was amazed at the typical Chrysler design items under that mere fwd 4-cyl car. A front K-frame, for example. About a 2.5" outlet on the cat converter, but the exh pipe decreased in size at each junction. NOT to forget how Chrysler normalized turbos to the general public, as GM tried to use them, but had issues in many cases (whether in the crudity of the software of the computers) or in the "no air cooling" of the unit itself.

Can't forget the Little Red Express Truck, either! A 360 V-8 with as much horsepower as a L82 Corvette, being the second best performing vehicle that year in the CAR AND DRIVER group vehicle test. Leaving the beloved Pontiac T/A 400 in the dust, no matter what tricks the Pontiac rep tried. Chrysler still built "fast stuff" IF one knew how to order the vehicle, by observation. FWIW.

Paint colors still had some good ones into the later 1970s, but by about 1979, everything had gone pastel . . . which evolved into the current "white, black, gray, red" colors of today. "Less" became better than "more", in many areas, which allegedly was less expensive to do. It might be amazing to see what profits MIGHT have been made if the "fewer is better" orientation had been done in the later 1950s, rather than "anything you want". Imports of that era came "as the factory allegedly wanted to build them, take your choice, if you don't want it somebody else will" orientation, which was just the opposite of what the USA brands did, by observation.

Look at how many things we lived through during those times! Having to wear seat belts, cupholders that were somewhere else other than on the inside of the glove box door, unleaded fuel and catalytic converters, but also the new things we ended up with (more stereo radios and tape/CD players, radial tires, interval windshield wipers, plus many other formerly-luxury options as standard equipment on pretty much everything). And NOW, horsepower is back, now being emissions-compliant!

Certainly, the "bean counters" will affect everything that is designed/engineered/produced, as always. No reason to lose money just because you can, so building it economically is always best, except for some specific "halo" models that are more advertising than mainstream.

Getting out of high school in 1970, I was there to watch a lot of these things happen, over time. In some cases, not realizing what I was seeing until years later. But it was exciting and fun to keep up with it all, for me.

Just some recollections,
CBODY67
 
One of that era's innovations that used to irk me was the separate lap and shoulder belts. The ones on my '70 Sport Fury spent most of the time unused, especially the shoulder belt, safely tucked away in the clips on the roof. I did use both belts on the long drive thru the desert at 100mph+ from Ft Hood to Oregon. Learned that Polyglass tires could not take sustained operation at 100mph+, peeled 3 on one trip alone. Goodyear hated me. In those days, the cops would pass you at 100mph like you were sitting still without a second look.

Dave
 
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One of tat era's innovations that used to irk me was the separate lap and shoulder belts. The ones on my '70 Sport Fury spent most of the time unused, especially the shoulder belt, safely tucked away in the clips on the roof. I did use both belts on the long drive thru the desert at 100mph+ from Ft Hood to Oregon. Learned that Polyglass tires could not take sustained operation at 100mph+, peeled 3 on one trip alone. Goodyear hated me. In those days, the cops would pass you at 100mph like you were sitting still without a second look.

Dave

I recall my DAD driving a Ford Country Squire at 105 mph on I-20 taking us east to Louisiana with no worry or compunction. That 70 LTD w a 390 was the best car my mother ever drove, until she got the little Dodge Caravan 20 yrs ago. She still drives it.

Aside from the cost of modern performance, it warms my heart to see some again. Still, I prefer the culture of riding down the highway in the back of my dad's pickup truck, him with a cold beer between his legs and a couple long shooting irons in the rack behind him, and not a seatbelt anywhere in sight. If folks wanted to be "safe" they dug holes, crawled into them, and fed worms. Now, the worms want special rights!

The greatest difference between the Daze of Yore and Now though is this: working folk could AFFORD the Good Stuff back then. NOW, folks have to hock themselves for a generation just to get by.
 
I recall my DAD driving a Ford Country Squire at 105 mph on I-20 taking us east to Louisiana with no worry or compunction. That 70 LTD w a 390 was the best car my mother ever drove, until she got the little Dodge Caravan 20 yrs ago. She still drives it.

Aside from the cost of modern performance, it warms my heart to see some again. Still, I prefer the culture of riding down the highway in the back of my dad's pickup truck, him with a cold beer between his legs and a couple long shooting irons in the rack behind him, and not a seatbelt anywhere in sight. If folks wanted to be "safe" they dug holes, crawled into them, and fed worms. Now, the worms want special rights!

The greatest difference between the Daze of Yore and Now though is this: working folk could AFFORD the Good Stuff back then. NOW, folks have to hock themselves for a generation just to get by.

In high school, a lot of kids drove and old pickup with a gun rack, usually with at least a 22 rifle in the rack. We thought nothing of it. Shooting sage rats was good sport. A lot of us shot at the rifle range at the high school. Imagine some poor kid that drove the same rig to school today. Sad commentary on what our society has become.

Dave
 
In high school, a lot of kids drove and old pickup with a gun rack, usually with at least a 22 rifle in the rack. We thought nothing of it. Shooting sage rats was good sport. A lot of us shot at the rifle range at the high school. Imagine some poor kid that drove the same rig to school today. Sad commentary on what our society has become.

Dave

VERY SAD! Today's children haven't any sense of FREEDOM at all! The Lord knows how badly the feddy voyeurs blackballed me! I won't get into THAT though beyond stating I'm a victim yet breathing.... While these crap computers do wonders for police statists, very few folks know how to use them to ENHANCE their personal liberty.....
 
Regardless of head casting the rebuild cost will be the same so do hardened valve seats.
Keep in mind the 915's will increase compression which will increase the chances of detonation on todays corn fed gas.
I personally prefer the 452 heads that already have hardened seats.
With a good 3 angle valve job and with some porting and gasket matching they will flow better than the 915 and no ping.
I have 452's on a 66 300 383 with a 68 301 cast intake. Works great!
1966 300 revival 038.JPG
 
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Regardless of head casting the rebuild cost will be the same so do hardened valve seats.
Keep in mind the 915's will increase compression which will increase the chances of detonation on todays corn fed gas.
I personally prefer the 452 heads that already have hardened seats.
With a good 3 angle valve job and with some porting and gasket matching they will flow better than the 915 and no ping.
I have 452's on a 66 300 383 with a 68 301 cast intake. Works great!

I've weighed the matter of compression vs flow carefully over the past few years, and want compression. The 383 I run now has ~9.2 compression, and runs nicely on 91 octane gasoline, without detonation once I started running the plugs the FSM specified, Champion J-14Ys. Not a solitary rattle of pre-ignition since I installed them! The hotter J-11Ys and J-12YC which Rock Auto wrongly lists as suited to 2 barrel motors DID give me trouble with pre-ignition, but now that I abide by the FSM, no problems!

The 516 heads I'm running now do well for higher compression, but the 915s offer the opportunity to more easily enlarge the valves a bit. I DO want to lower back pressure some, hence going to 1.74" exhaust valves appeals. I don't have any reason to desire larger intake ports, but will accept them if a machinist feels compelled to do it along with the exhaust ports.

IFF on the other hand, I HAVE to run the 452 heads I have, for some UNforeseen reason, I reluctantly will. Otherwise, I might sell them. Time will tell in this. (Same for some 906s I copped dirt cheap) I want more than 8:1 compression on that motor though, and believe I can design a build to give me the 9.2-9.5:1 pop I desire with good results. I want a motor that will give me plenty bottom end torque, and which will lug around the 2.1 ton car in urban traffic smartly. I might see about a small (500 cfm) 4 barrel carb, with strict mechanical choking and linkage which will permit me to use the small primary jets for good gas mileage. but enough secondary breathing when needed too. The new AVS2 carbs look promising here.

All the high flow stuff suits designs of high revving and large volumes through the motor. This won't work for us one bit. I like the Hughes RV cams, if the one in the 400 now isn't usable....
 
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