Head Welding Rod Type?

[Tim Hancock]

I just dropped my 79 SC 3.0 to repair some screwed up exhaust port studs. The previous owner had a hack mechanic and he totally mutilated two of the stud holes with multiple holes drilled at crazy angles in the general vicinity of the exhaust studs, then he jb welded the studs back in! I would not have believed it if I had not seen it.

I have a tig welder and was wondering if any one knows what aluminum rod is best to use to fill the holes and then remachine?

[Porsche_monkey]

They can probably be timecerted, timecerts are quite large. No welding required. Worked for me.

[Tim Hancock]

Believe it or not, this dumb #@%tard actually drilled it way out. I have 1/2-13 inserts that are not big enough! The side wall of the boss has been compromised and I am left with either replacing the heads or welding. I am sure that when cleaned up properly they can be welded, but I would rather have someone who has done it before tell me what filler rod to use. I will preheat the head to help the process. Hopefully I do not end up with cracks.

[racing97]

4043 or 5356 (the latter my choice) will do the job, one pound or so will be enough, whatever minimun the Weld Shop will sell. You probably have an idea on rod size, a 3/32 will work if the size of the hole will support the dia. if not 1/16.

Good Luck

[Porsche_monkey]

Anyone else have a bad feeling about this? I would think an aluminum threaded insert TIG welded into place might be better.

[john walker's workshop]

you can usually come up with a head for $100 or so.

[Porsche_monkey]

Excellent fallback plan Mr Walker.

[Tim Hancock]

Thanks guys, I have both of those types of rod. If my idea fails, I will look for two heads, however, I do not see any harm in trying this. All I have to lose is a little argon. I did not intend to rebuild this engine at the
present time. I just purchased the car and planned on driving it a little this summer before doing anything major. The engine drop was simple using W.D.'s books. The engine bay needed some clean up and some oil leaks looked at. The car runs decent, does not smoke and has decent compression. Oh well the fun begins.

[Porschephd]

If I am reading this right you are going to do this while the motor is together? If you weld on that head, and that can be done wihtout issue you will cook the seal and the guide right out of that thing. Please keep that in mind when you are headed down that road.

[Fishcop]

Tim, take some before and after photos for us picture junkies won't you?

[Tim Hancock]

Stephen, I will probably pull the head. I dont think the valve stem seal would take the heat, but do you really think the guide would melt?

Basically this just sucks, fixing someone elses shoddy workmanship with what some might feel is also bad practice.

[garibaldi]

Two cents, you should be using Argon/ helium mix as a shielding gas, and to make welding easier, clean thouroughly and preheat the head on a stove or an oven. Ohterwise you will be spending time trying to get a good knit while the rest of the material is sucking all your heat away from the area. Keep washing the area with the weld pool since you will probably get a fair amount of contaminants come to the surface. Grind them off and then go back and wash with the weld again.

[rick-l]

How big of a TIG machine does it take to do this? Is the hole a big crater your torch will fit in?

here is another welding site moderated by Miller weld specialists
http://www.millermotorsports.com/mboard/

[Tim Hancock]

Here is a quick sketch (being that I am at work now) of what I am up against.

[racing97]

Tim,
I had a feeling you could handle this and it looks like it. The Helium is a great idea and I bet your equipped for it. Contamination is a battle as I am sure you are aware, that Carbon is deep into that material. So Hi Freq.
Also when you are finished throw an 8 x1.25 insert in it and I think you will be smelling like a Rose.

Best regards

[Tim Hancock]

Thanks for the vote of encouragement racing97. Well I do not have helium, but I ran a tap drill for 1/2-13 thru my drill jig
and half the hole cleaned up. The other half had been filled with some sort of JB weld or something. I have aluminum etching/cleaning acid which I will use before I start welding. A previous post above mentioned
that he thought the valve stem guide would melt. I think it should be ok but I am not sure. Have you ever welded on one of these cylinders Racing97?

[racing97]

Tim,
Yes I have had experience welding Porsche heads, and
with due respect to the valve guide proximity,
I don't believe that will be a problem, due to the distance you are from the guide, remember at some time shortly after the valve opens the guide sees quite a bit of temp as a function of the exhaust process.
I think your problem will be removing that JB substance, as you know aluminum contamination is going to be your worst enemy. Get all that junk out of the hole even if you have to burn it out then etch.
Good Luck

[Tim Hancock]

Thanks again racing97, I have removed the crap but before I heat then weld I will go at it in a serious way. I have constructed fuel tanks for aerobatic planes out of 5052 .050" alum sheet and I clean multiple times in between tacking and welding with etching solution and a clean SS brush. I think this will work out. My problem now will be to make myself just fix the problem because I really just cannot start my "restoration/rebuild" at this time (much too busy).

[Tim Hancock]

Pictures of:
Tool for drilling out studs I made, the fouled up cob job I found
and the poor car minus it's heart.

[Porschephd]

Lord that is terrible. BTW I recommend A356 not 5356. It is far better suited for welding up cast aluminum. Most don't even know it exist and will try to sell you 5356 and think you are nuts or think you meant 5356. We only have two places in Kansas City that even stock it. It welds much better. I also use a 25/75 Helium Argon mix as Christian suggest.

As far as the guide, I doubt that will be an issue, but certainly a concern. I was unclear how big the hole or how deep.