I am opening this thread, as Ed @ FTI wanted ask a bit more about the Welding and heat treatment of the Patriot Cylinder head package.

This was brought up on Corvetteforum, unfortunately, Patriot isn't recognized as a supporting vendor there (although Terry has been working to try to resolve that). So, the entire discussion on Patriot heads was deleted.

I am bringing this thread back up to give us all a chance to learn a bit about proper cylinder head welding, and to help resolve any question anyone might have regarding this process on the heads Patriot is offering, or any other Patriot question folks might wish to pose to Terry.

I would like to invite Terry to explain again, who is doing his welding, and how it is done, along with any other technical details he feels is worth including to this discussion.


Here is Ed's question:

<font color="blue"> J-Rod:
Still awaiting the Patriot "welded" head thread to be reopened on Corvetteforum.com. I have a bunch of Tech questions on heat treat and head twist that need to be asked... <!--color--></font>

 

The link below is an article I had read when I was researching the heads before I bought my set. There is also one of the nations leading induction heating equipment manufacturers and process developers here in town, (I was a development engineer there for 5 years and my dad still works there) I have talked several times with their metalurgist about "welding" cylinder heads and the implications from it. I'll try to get him to email me a summary of what we discussed and I'll post it on here. The company's name is TOCCO. www.ajaxtocco.com

here is the article about aluminum head welding.
http://www.tomorrowstechnician.com/tt/tt80276.htm

 

The welding of the heads are done in house.The heads as a raw casting are heated,then welded up (using the desired type of rod).The heads are heat treated before any of the machining has occured.The heads can be heat treated because they are made of 356 aluminum.

 

I have a question about the welding,filling in process.

How much material is welded into the head and where[chambers,intake,exhaust ports]?

I have seen on 2 sets of heads that were taken off a car that overheated that the head became soft.How is your process done to avoid any problems with the head such as softening or warping? TIA.

 

The heads are welded when they are a casting.At this point no machining has been performed.The heads are heat treated to a356 t6 specs before machining.When the machining is performed to the factory specs,there is no warpage.The heads are brand new.This head will be no different than any other aluminum head,if you run the heads hot,there is a chance of warping.There is about a 1/4 of material added in the chambers.

 

Are the heads stress relieved (shotpeened, etc...) before the heat treatment process? What are they heat treated to?

 

Not being a metallurgist, I'm sure my terminology is wrong, but I'll take a shot anyway:

I'll preface by saying this could make a lot of sense or none - I'm just trying to understand how this stuff works a little bit

When welding the head, do you end up with a discontinuity in the metal structure between the welded part versus the castings? I've been told that cast metals will have a particular porosity or other such properties. Then, the additional welded material might have different metal characteristics than the rest of the head, despite any heat treating?


Curious,

-Jake

 

We have no problems with porosity.When welding aluminum it takes skill to not have any mismatch.

 

I see you take the heads to T6. What is the heat treating process, time and temp for that. What type of ovens do you use? Are the ovens calibrated by a service or do you do your own in house calibration? Is the temp monitored on the head by thermocouple, or do you just go by time?

 

I would think when the head is welded up and heat treated then the welded chamber machined to spec, this would elimate any porosity issue. ie better than stock heads in regards to porosity.

 

We do not heat treat the heads at Patriot.They are heat treated in Ohio by the same company that Canfield Cylinder Heads uses.

 

ok now are the seats installed during the welding or after? are they installed during the heat treatment? That would be my biggest worry. I have heard of and seen seats fall out due to too much welding(overheating) of a cyl head. The heads get soft after being heated up so much. What is the name of the company you use to do the heat treatment?

 

The heads are heat treated before any machining is performed.Meaning all of the tapped holes,milling of the intake,exhaust and deck surfaces are performed after the heat treatment.The seats and guides are installed last.