Porting heads, punched an extra hole in one of them. Don't you know, it was the last 20 seconds of the last grind on the last port ?!! arrgh. right on the spot where the cores met - a little low on material there.

Fixed with aluminum brazing rod and a bernzomatic w/propane. melting point of the rod is about 720 F. Took about a half hour to heat it up, evenly, took about 35 mins to heat the head sufficiently. Haven't smoothed it yet but it will look brand new when done. The material is super-tenacious.

http://www.patentsearcher.com/hole1.jpg

http://www.patentsearcher.com/nohole.jpg

 

Do you think that type of thing would work on aluminum valve covers? I tried it the other day and it didn't want to stick too good. Maybe I didn't heat it up enough? I wouldn't think you'd have to heat valve covers that long. Someone put breathers on these valve covers which I can't use; when I took them off it left several 1/4" holes.

 

Ouch!!

 

LOLL , my heart sank when I first saw it.

 

It would work, my hole was about 3/8. Trick is in getting it hot enough.On a valve cover I'd put it in the oven at 450 for half an hour, pull it out and then apply heat to the area needing repair. Just don't melt the rod in the flame - the rod must be melted by the heat present on the part itself, like soldering. I noticed that putting heat right to the area didn't work. Rather, had to heat adjacent to it, so when the heat migrated it would go to the spot - you have to force the heat. I cheated, I used two torches.

 

wow glad you fixed it.

 

Nice job. Probably much better than Mighty Putty ;-)

 

Thanks for the info. I'll try again when I can. I have two torches, maybe that'll help. I wouldn't have thought of using them both!

 

That will take any and all heat treat out of the aluminum making it T0 or the strength of aluminum foil at best. A TIG weld will make the weld area T0 but is so quick and localized the rest will not be affected. I would be careful putting that much heat into a cylinder head as if the heat treat is lost the head gasket will cut into the deck surface causing a failure down the road. If you weld an alloy engine component be sure not to use 5356 rod as it is not made for service over 150 degrees due the stress corrsion cracking..

 

I feel your pain...I felt the same way when I saw my intake boo-boo!

So... Are you sure that much heat won't have warped the head? Will you mill it for security?

BTW: That doesn't look very much like a C6 to me!

gp

P.S. Did you see the link we posted for you of a SR for LT1 on fleabay (a week/two ago)?

 

Aluminum alloys used for cast cylinder heads is normally a heat-treatable alloy that develop mechanical properties through a solution heat-treatment, quench and age hardening process. The heating and cooling cycles the head undergoes during normal engine operation is very similar to the artificial age hardening heat-treatment process that gives it its initial strength. So, in effect, it gets a heat treatment every time it is thermally cycled.

The excessive strains that the joint between an aluminum cylinder head with ferrous fasteners might experience is mostly due to the CTE mismatch between the fasteners and the clamped aluminum head material. The relative stiffness of the two mating parts is a function of the two mating materials' MoE and their section properties, and has absolutely nothing to do with tensile strength.

 

warpage could occur but won't if one heats evenly, and not excessively, and doesn't subject the workpiece to any thermal shock. aluminum doesn't begin to warp until about 1165 F, unless you shock it thermally. given my rods melt about 735, there was a 500 deg safety margin.

of course I checked it and the deck-mating surface remains flat.

 

 

Mighy Putty makes me think of Billy Mays. Word on the street is he was strangled with a Sham Wow...

 

I got busy and didn't visit the link, but thanks alot for sending it.

Here's a link to a vendor of the material I used below. I bought the rods I used from a retiree selling it at a gun show of all places. I've had good luck in acquiring tools at gun shows.

http://www.aluminumrepair.com/faqs.asp

 

Chris get a copy of at least 'Machinery Handbook' Read about heat treating. sigh.. you can not weld on a head and expect to heal itself over time it is not going to ever get back all the way to where it was. Surface hardness is a very important feature in an alloy cylinder head it keeps the gasket surfaces intact..

 

Sure I can. And I did. I'm going to run it, and if it fvcks up, its my problem, nobody elses !! Thanks for your concern.


Ed+ ---- look at the annealing point for that alloy, consider that heads are routinely heated to 450 to remove valve guides and realize I only hit 380 C, an insignificant temperature in the grand scheme, in a tiny area. bwahahahaha !! Its welding that messes things up, not this low temperature, localized brazing.

"Several hours at annealing temperature are required to fully soften heat treatable alloys."

http://www.alcotec.com/us/en/educati...-selection.cfm

I suggest you consider writing to the company that makes the HTS-2000, I'm sure they'll be happy to answer your concerns better than I could. Have a great day.

 

Moreover, heat treating produces a different crystalline structure than is initially present in an as-cast form. One well-known method scientists employ to determine changes in crystalline structure as a function of temperature is Differential Scanning Calorimetry, or DSC for short. A sample is prepared and loaded, and the temperature slowly increased and absorbed or emitted enthalpies are plotted as a function of temperature. The resulting thermogram provides an exact indication of where exactly on the temperature scale changes in crystallinity, grain boundaries, and domain energies occur. For A356-T6, DSC plots are available and if you would like to see a link to one, check out FIG. 9 of US patent 6,299,665 or any other DSC of that alloy. What is evident is that no changes occur until one hits temperatures normally associated with conventional welding are reached (over 550 C), which is why I did not tig it.

Further, aluminum foil can have a wide range of tensile and elongation moduli depending on how they're prepared. When I worked at Gould Electronics, then the #1 supplier of metallic foils to the world electronics circuit industry, we were able to provide foils having higher tensile, elongation strengths than the corresponding cast materials by control of process variables. It was there I made my first patentable invention, US 5,017,271 which became a standard in producing fine-line traces for printed circuitboards for over a decade and is still used today. Thus, aluminum foil is not necessarily "weak", just thin and perceived that way because of its thinness. Nine micron tungsten foil is similarly perceived as wimpy.

In view of the DSC thermogram for A356-T6, your assertion that I've somehow destroyed the heat treating on that cylinder by low temperature brazing the hole on that head closed is false.

 

I ended up stick-welding the valve cover holes. It seemed to hold better than the aluminum solder process. Probably the best way would have been tig or mig welding them but would require a new welder (expensive).