Value of heads

[kell]

Description: how much are these heads worth, approximately

I saw mention in another thread of heads being worth ~$1200. This is way more than I had any idea of heads being worth. I still have the heads that I took off my 1952 FL that I replaced with new STD heads. The previous owner had them rebuilt, but something about the front exhaust was wrong. Some oil would come out the exhaust pipe from the front cylinder. The front exhaust rocker arm broke a few months after I bought it. These things could have been caused by something minor like a bent valve stem, but I remember the P.O. saying something about a problem they had when rebuilding it. This is all just by way of full disclosure, since this thread is basically: how much are these heads worth, approximately?

[Cotten]

Kell!
I was referring to overhead oiler heads, made only from '63 through '65. They definitely command a premium price, and are what the original STD's were patterned after. (Pity that they went weird on the ports, but back then heads were a dime a dozen.)
The next priceyest vintage would be fronts around the '61 era, as so many of them had fins hammered off above the circuit breaker.

55 only heads are dear because they not only were one-year-only,... they were fragile around the intake ports.
'56 castings up to the big-finned '61s can command $800 for complete "serviceable" assemblies, if un-molested. Cut that in half if they have been "rebuilt".

'49-'50's are common, but usually trashed. '51 to '54's are most common, but most commonly boogered with faulty nipple conversions and knarfed rivet bosses. Such heads abound at $150 a piece, but cost twice that to return to service.
Any head that has had "unleaded seats' installed is a marginal gamble,...overpriced and often a time bomb.

[57stroker]

Is there any way to replace bronze seats if the heads have had hardened ones put in? How did Harley put the brass seats in and get them to stay? How do they put seats in modern aluminum heads? I have access to a lot of good machine tools and usually more time than money. I am looking for fixes when (not if) my hardened seats fall out. Again, I sure wish I had met you BEFORE I put my basket Pan together.

[Cotten]

The original bronze seats are cast in. They have tangs that extend into the aluminum to hold them.
There are (atleast) two reasons for difficulty with installing pressed hardened seats in Pans. I shall address the geometry ones rather than the skill of installation variables.
The first is that the seat cannot be as deep as in a chubble. the smaller area of contact reduces heat transfer, and makes it easier for the steel to reach a critical temperature where it will shrink and fall out.
The second is matrix support, although this is really the same as the first problem in that it is why the seats cannot be as deep: The intake port is so close to the seat that the aluminum will often crack away from the pressing operation, and even when it does not, the seat can distort prematurely from uneven (or lack of) support beneath that portion.

("Beneath" meaning under it as you look at a head on the bench. In the motor it is above it, of course.)

Custom-cutting two lengths of seat, one for the intake, and a longer one for the exhaust , was a hedge on the bet for the exhaust, as it is the one most likely to overheat. But most shops were either obsessed with geometry, or did not want to invest in a large stock of expensive inserts.
Another over-looked hedge on the bet would be to install bronze seats instead of hardened steel. But for years I have searched for a source.
Thankfully there are now providers of the superior spray-welding technique!
Another inherent problems with Pans are porous (WW2 scrap) castings that easily crack to a bolt insert at the large interferences necessary with a hardened steel insert. The biggest problems, however are the sources of the heat in the first place... lower octane fuels, increased compression from successive overbores and 'performance' cams,etc., ....and last but not least: tired and boogered up manifold nipples with generations of abuse!
If your original seats are already cut away, then skill and technique becomes your last resort. We should probably start a whole new thread for that one. And seek out bronze inserts as well. (Hardened seats are greatly over-rated!)

[PanPal]

What if hardened seats were threaded in place? How about forming some of the casting over a slight lip on the outer edge of a hardened seat? I guess aluminium wouldn't roll form well ???

[Cotten]

Consider the expense and trouble to tap the counterbores in the head, which could vary greatly in diameter, as well as turning threads into the hardened inserts! PLUS the airgaps involved with threads are insulating voids such as we are hoping to avoid at all cost.
Peening or rolling the matrix casting to retain the insert is indeed a time-honored practice. Even my antique K-O Lee aparatus (which is primitive to say the least) includes tooling to do so.
But it is only a "clinch" for a little security, not a sure cure for the problem. If a seat shrinks, it will eventually move.
Clinching works best with cast iron. Aluminum is mud by comparison.

[57JOHND]

Cotten,

Your expertise and wisdom are beyond words.
In your opinion what is the best method, given todays readily available fuels, for valve seat repair?
Please presume a basically stock motor, or close to.
No intentional raise in compresssion via camshaft timing, overbore, or head milling etc.
Most of the motors are not standard specs any longer from either boring or resurfacing.... so there will need to be a litttle leeway.
I simply ask because I know I will face this in the somewhat near future on mine.
I am not real warm on the idea of hardened seats (Thanks my lucky stars to this forum)
however I would like to have a reasonble degree of confidence in the overall durability of what direction to go.
The "alternate" fuel availability is still pretty good here (ie leaded race) but it only gets me thru the first tankfull from home, and then" the pump."
I guess in an aroundabout way Im asking "what do you run?"
Thanks for taking of your time.

[Cotten]

RE: "Best Method"..
Although I have no experience with the 'new' process (I got out of commercial engine building), there are providers of spray-welding services where the original bronze seats are built back up and then re-cut to blueprint specs.
Sources escape my memory, but one advertises in the AMCA mag.
If your seats are already cut out,..you are in the same boat as I am with my own sets of heads that I installed hardened seats in myself, some time ago, but untested.
We MUST run them anyway!.
It is imperative however, that all chances of overheating are prevented. This means that all clearances are to spec, timing and valve adjustments are dead-nuts,..experimentation be kept to a minimum when applying a carb,... break-in must be as gentle as possible,... and above all, there cannot be even a trace of an airleak on the intake tract.
Anticipate any problem if you wish to avoid a chain reaction. Then the hardened seats should service even better than bronze...in theory anyway.

PS: I have experience, yes,.. but only enough wisdom to focus quite narrowly. Thus carbs and manifolds are now all I 'practice' upon.

[me]

Headhogdsullivan@netscape.net does the metallic spray overlay back to stock specs.

[kell]

Cotten
You say $150 apiece, that's per head, i.e. $300 for the both of them?

[Cotten]

Kell!

Let me start right off by stateing that I am not a wheeler-dealer of used parts, nor am I referring to any specific opportunity!
As all speculators know, a part is more expensive if you ask for it than if it is offered outright.
I base my estimates on the priceyest market I know, the Davenport Meet every Labor Day. And everyone knows that mostly crap gets thrown out for sale at meets, so even $150 per head can sometimes be too much.
Last D-port I had a customer's pair of '48-'49 cylinders and heads complete in the booth as a reluctant courtesy at $650 for all. There wasn't even a serious offer on them.
Of course they are "chopper grade". By the time you helicoil everything and sink another $750 into normal rebuilding,... you've still got a $650 top end, with crappy chrome pans and probably a max'd overbore. (pistons with a cylinder at a meet just means ashtrays included.)
That's why I do not deal in RAW used hardware.

[headhog]

JohnD,
Go to http://www.headhog.com I do a process to the cast in bronze seats check it out. HEADHOG and welcome to the forum.

Cotton,

Very good information on the cast in seats. The real problem with the steel seats coming loose is that the thermal expansion coeficients of aluminum and steel vary so greatly, especially a green sand cast alunminum,which by the way is what the panheads are.The green sand cast aluminum Panhead will,in the exhaust area expand at least .005-.006" The steel inserted seat will not expand more than .001"-.0015". guess what? seat is now loose. Thanks again. With my metallic overlay process we are build upon the original bronze seat with a material that is compatable with unleaded fuel. HeadHog. http://www.headhog.com And I do advertise in the antique motorcyle club of america (AMCA)

[Cotten]

Not only do the thermal expansion coefficients make the interference marginal at high temps, the shrinkage problem is paramount.
Hardened steel seats shrink permanently if a critical temperature is reached. This is how seats occasionally come loose and even fall out!
Many of you have observed case or rod bearing races that have spun, or rods that have somehow gotten tight during break-in. Races are made of a similar steel as hardened valve seats, and if an oiling or alignment problem gets them hot, they also shrink. This shrinkage is a matter of how the molecules of the steel mixture align themselves at different temperatures.
The best demonstration of this is to suspend and stretch a length of piano wire and put some healthy amperage through it. As it warms, it will start to expand and droop, but at one point it will tighten up again before returning to its expansion until finally melting. Another application of this phenomenon is to remove blind races (or valve seats!) by welding a bead around their face, thus shrinking them loose.
Thus, critically high combustion temperatures must be avoided.
Today's low octane fuels burn hotter, often inappropriately for a higher compression motor. Under heavy loads or high speeds, ANY minor malfunction such as the points cam wearing, or the tiniest of manifold leaks can light the fuse to a 'catastrophic failure'.

[headhog]

Cotten ,
Once again good info. The upper critical temp for moly or chrome vanadium steel( which the seats are usually) is approx. 2,900deg f. The exhaust area will never get that hot or affect the ferrous seat other than to make it expand approx. .001" if that The green sand cast panhead in that area will expand approx. .005-.007. That is the cause for pressed in steel seat failure. HEADHOG http://www.headhog.com

[DJ]

headhog....

The heads on my '60 motor have only been re-done twice. I owned the bike almost 25 years ago, and had the heads redone for the first time. I sold it to a guy that had them redone once also. I bought the bike back from him in May '04 and have not taken the heads off yet because there is only just under 6000 miles on his rebuild. My question to you is how many times can OEM seats be reworked before your overlay process would be considered?
A simple question, but I don't know the answer. Thanks.