440 Head Selection Help

[Bruzilla]

I need some help with choosing heads for my 440 project. The engine is a non-HP 1973 block produced in 1972. The engine currently has 346 heads on it. I have a guy trying to sell me a set of 516 heads. I'm looking at this engine going into a street car with 400-500HP, so which heads would be better? Thanks

 

[RustyRatRod]

By far, the 346s. The 516 heads have closed chambers, which is good for compression, but they have small ports which is bad for flow.....at least on a large engine like a 440. There are instances where it can be good for velocity, but you'll want the larger port heads. I am using some 516s for my 383 build, but it's a 383 and they will be ported. Even still, the 346s have more potential.

 

[moparsteve636]

The 516s will need harden seats installed to run this crap they call gas! You could go with a pr. of 440 Stealth heads for not much more than you'll have in the steel ones after doing a valve job and good springs! Much lighter also.

 

[Bruzilla]

What's a set of 516s going for these days?

 

[RustyRatRod]

Meh....not much. Ain't much demand for them really. Cause first, you need to install the larger 1.74 exhaust valves......unless you plan on going even bigger because they all had the small exhaust valve. Then, if you want the hardened seats you have that expense. Plus of course guides unless they are somehow milarulously good or have been replaced before....plus intake seats if they are beat all to hell. BUT I'll say this. I've seen several sets and they ALL were in great condition. I think the metal was better back then. Also, IMHO, the hardened seat thing is overblown. I think unless you're really going to pull heavy loads such as with a truck, or you're racing, the hardened seats are an unnecessary expense. Not to mention, they will always be hanging out waitin for gravity to pull them out. I'm not going to run them in my 516s, primarily because the original unhardened seats look so good, I could lap the valves in and GO. That tells me the metal is hard enough. It boils down to a personal decision really. Some people cannot sleep unless they have hard seats in everything. I mean hell, you can get lead substitutes and dump in the tank all day long. That's a lot cheaper than a seat fallin out. JMHO.

 

[67 coronet]

run the 346s with a good valve job and springs to match the cam.you will be happy while saving a bunch of cash.if you dont end up with power to your liking,you can always upgrade later.

 

[Meep-Meep]

The only difference that I can see between the 346 and 516 is the chamber. Ports look the same even compared to 915 and 906. Both types (516 and 346) have flat intake port floors and that is not too good for the transition around the corner into the valve pocket area. Yes, they both can be made to flow adequate amounts of CFM but I don't think that's the whole story. You can completely ruin a port and get more CFM at the same time. Where I think the magic happens is starting with a port that has the best wet flow, and the earlier 915 or 906 head may be a better choice if you are staying with the factory iron. If you want a quick and relatively cheap compression upgrade use the 516's. likely both your heads will need the same amount of work, including hard seats, so no harm done there.

 

[69Bee]

I disagree Rusty. This is what I do for a living, and with the extinction of leaded gas, hard exhaust seats are a must. I have seen iron heads from cars that are so bad, the head of the valve has burrowed below the chamber surface.

I always recommend hardened seats to my customer, but it is always his choice in the end. I get $96 to install 8 seats, and the cost of the seat itself, usually between $3 to $7. You will surpass that price in about a dozen fillups with lead substitute. Induction hardened heads can be tricky. How many valve jobs have been done before? How thick is the hardness? For $96 plus the seats, you don't have to worry about it going bad.

As far as the seat falling out, with a proper installation job, you have just as much chance of a failure as a replacement guide falling out, or a cylinder sleeve moving, or a pin bushing failing. They have been using seats in aluminium and diesel heads for decades, and I have only seen one failure in all my time doing this. A seat should have between 0.003" to 0.005" interference for an iron head, and 0.007" to 0.010" for an aluminium head. That is a hell of a lot more than a guide at about 0.0015" to 0.002".

As far as the heads, the 516 will bump compression, but has smaller ports like Rusty said. The 342 head has larger ports, and was based off of the 906 head, just with induction hardened exhaust seats. Use the 342 heads, and either run the seats like they are (with a valve job of course), or put the hard seats in.

 

[lewtot184]

i think there's a lot of foggyness when it comes to iron heads. this is my understanding; the 915-906 intake port vs the 346, 902, 452 intake port is one flows a little better in the mid-range while the other is a little better up top. i think average flow is close to the same when modified, so there's probably no big power differences. the late intake port is easier to work with, so i've heard. either with a good pocket port and valve job will make 400hp. to get into the 450hp range i'd do the big valve treatment with the correct pocket work on either head. the exhaust ports are basically the same. what i hear about 516's is they have a casting problem. some porters won't touch them due to poor quality castings and some say there isn't a problem. i have no direct experience but would probably approach the 516 with caution in a max effort. hugh's has a "pro-pocket" head that may be worth looking at for a street head. it should easily do 450hp without breaking the bank.

- - - Updated - - -

I disagree Rusty. This is what I do for a living, and with the extinction of leaded gas, hard exhaust seats are a must. I have seen iron heads from cars that are so bad, the head of the valve has burrowed below the chamber surface.

I always recommend hardened seats to my customer, but it is always his choice in the end. I get $96 to install 8 seats, and the cost of the seat itself, usually between $3 to $7. You will surpass that price in about a dozen fillups with lead substitute. Induction hardened heads can be tricky. How many valve jobs have been done before? How thick is the hardness? For $96 plus the seats, you don't have to worry about it going bad.

As far as the seat falling out, with a proper installation job, you have just as much chance of a failure as a replacement guide falling out, or a cylinder sleeve moving, or a pin bushing failing. They have been using seats in aluminium and diesel heads for decades, and I have only seen one failure in all my time doing this. A seat should have between 0.003" to 0.005" interference for an iron head, and 0.007" to 0.010" for an aluminium head. That is a hell of a lot more than a guide at about 0.0015" to 0.002".

As far as the heads, the 516 will bump compression, but has smaller ports like Rusty said. The 342 head has larger ports, and was based off of the 906 head, just with induction hardened exhaust seats. Use the 342 heads, and either run the seats like they are (with a valve job of course), or put the hard seats in.

i agree with this concerning the unleaded seats. if they weren't necessary detroit would have never went thru the tooling and expense.

 

[Bruzilla]

Lots of great information here, and I thank all of you for it. I'm am by no means an expert on heads, obviously, but I am someone who always looks for consistency. In this case, while leaded gasoline was banned effective 1996, it's use was progressively curtailed starting back in 1973. I've been driving since 1976, and never even got a chance to buy leaded gasoline until 1991 when I found one little independent station in southern Maryland that was selling it, and I'm doubtful it really was leaded as I can't see a little mom & pop paying for a tanker to bring that fuel just for them and being able to afford to charge about the same as for unleaded fuel.

Anyway, I think it is safe to say that every engine out there has been running on largely unleaded fuel since at least the late 1970s. If this assumption is correct, and the contention that the use of unleaded gas with unhardened valve seats destroys them, I would expect to see every set of heads with unhardened seats being damaged, but it seems like a lot of them aren't. Some have been destroyed, and some show no damage, so I'm thinking the issue here isn't just the gasoline and the seats, but some combination of conditions that are not common to every engine.

 

[RustyRatRod]

The single biggest contributor to valve seat recession is a dirty air filter. Although proponents for hardened seats argue otherwise. ;)

 

[lewtot184]

Lots of great information here, and I thank all of you for it. I'm am by no means an expert on heads, obviously, but I am someone who always looks for consistency. In this case, while leaded gasoline was banned effective 1996, it's use was progressively curtailed starting back in 1973. I've been driving since 1976, and never even got a chance to buy leaded gasoline until 1991 when I found one little independent station in southern Maryland that was selling it, and I'm doubtful it really was leaded as I can't see a little mom & pop paying for a tanker to bring that fuel just for them and being able to afford to charge about the same as for unleaded fuel.

Anyway, I think it is safe to say that every engine out there has been running on largely unleaded fuel since at least the late 1970s. If this assumption is correct, and the contention that the use of unleaded gas with unhardened valve seats destroys them, I would expect to see every set of heads with unhardened seats being damaged, but it seems like a lot of them aren't. Some have been destroyed, and some show no damage, so I'm thinking the issue here isn't just the gasoline and the seats, but some combination of conditions that are not common to every engine.

there are variables. valve spring seat pressure and engine speed are two. keep in mind that the erosion is actually the valve and head seat area spot welding to each other. all auto's from model year 1975 and later were required by law to use unleaded fuel only. beginning in 1971 oil companies started making low lead fuels (compression ratios took a dump about this time). the leaded you bought from mom and pop was probably the low lead. low lead may have had 90% less lead in it than a leaded premium would have had. "tetraethyllead" is a lubricant and anti-knock additive.

 

[YY1]

When I started driving, in Ohio in 1984, most stations had Regluar, Premium, and Unleaded.

Most that had previously offered a leaded mid-grade, removed it, to facilitate the unleaded.

There were also stations with orange signs (don't remember brand, but all were orange) that had 10% ethanol.

I remember vividly, the old Sunoco pumps, from the 70's and earlier, where you dialed an octane rating from a selection five or six.
I remember watching the attendant do it, and then there was a really breif window, when self serve and full serve existed at the same time, and you could do it yourself. I also remember my uncle telling my mom she needed at least 100 in her 67 383 Newport.

I also image that most pre-73 cars that had valve seat damage probably went to the scrap yard during the 80s and 90s, unless the owners bought used heads (or engine) or ponied up half of the car's value to get them fixed.

I know a cracked head even on 80's cars usually meant soul searching to decide if a used/reconditioned head expense was worth more than the car.

 

[Meep-Meep]

Valve seat recession is not a figure of ones imagination. I have seen it. Even replacement seats can fail. The hard seats I have seen are not actually hard and I believe their high nickel content is what makes them resistant to the pounding of the valve.

 

[RustyRatRod]

I think there are two main factors regarding valve seat recession. Like I said in my last post, a dirty air filter will get minute particles of dust in and grind the hell out of valve seats and faces. Secondly, valve guide wear is another big factor. Excessive guide wear allows the valve to flop around in the seat and beat the seat out.

There's even a school of thought that says the old lead was a partial cause of valve seat recession because lead particles were crystalizing on the valve seats and faces and acting like sandpaper. It's an interesting subject with a lot of views. I'm no engineer and I haven't done a study on it, but I can say one thing for sure.

I've done machine work in the past. I have seen heads with hardened seats that were beat all to hell. I've seen heads without hardened seats in perfect shape and only require lapping in, so I don't think there's any one hard and fast rule and I am not smart enough to argue the point.......only tell you what I have seen. Lastly, valve seat inserts CAN and DO fall out. I don't care who puts them in and how good they are. It is just something I would always have in the back of my mind. Meep-Meep is dead right, though. Valve seat recession is not imaginary. It's my belief though that the things I described contribute to it much more than whether the seats are hardened. Were that not the case, I believe every head with hardened seats would be in good shape and every head without would suck, and that's certainly NOT the case.

 

[lewtot184]

Valve seat recession is not a figure of ones imagination. I have seen it. Even replacement seats can fail. The hard seats I have seen are not actually hard and I believe their high nickel content is what makes them resistant to the pounding of the valve.

i think it's a matter of dissimilar metals that won't weld to each other.

 

[Bruzilla]

Valve seat recession is not a figure of ones imagination. I have seen it. Even replacement seats can fail. The hard seats I have seen are not actually hard and I believe their high nickel content is what makes them resistant to the pounding of the valve.

I don't think anyone is denying the existence of the problem. What's being discussed is the cause. The conventional wisdom has been for decades that it was unleaded fuel, but the inconsistent results indicate there's probably something else, or more likely a combination of factors, that actually cause the problem. If unleaded fuel were really the culprit, we would expect to see damage on most every set of heads that don't have hardened valve seats and that's not the case.

 

[RustyRatRod]

Take right now for instance. I have a pair of unmolested 516 heads. The seats and guides are absolutely perfect and they have never been replaced. It's not a coincidence, as I have seen it many times before and I know others have as well. It makes me curious as to what the common denominator is to heads WITH worn seats.

 

[Meep-Meep]

Again, the material of the replacement seats is not hard. As Lew pointed out it may be the dissimilar metals or because nickel is a good metal if you want good resistance to wear. Rusty is also spot on that there are a lot of factors contributing to seat wear and a crappy fit at the guide is a recipe for disaster. Other factors are heat, duty cycle (high continuous RPM) and sloppy work in general. The theory I read is that when the lead in the gas goes through the combustion process the lead turns to an oxide and that oxide coats the valve and seat on it's way out. Oxides are hard so it makes sense that having that protective layer will help.