Automobiles Forum banner
1 - 17 of 17 Posts

·
Registered
Joined
·
3,280 Posts
Discussion Starter · #1 ·
this is on my "new" nf head....the wedge/casting flaw is full of carbon so it was like that for a long time. the car had 176k miles on it. There's no evidence of it causing a compression leak into the corrosponding cylinder so i'd think it's ok....just a bummer to see that. I can't believe i just noticed it!
 

·
Registered
Joined
·
17,178 Posts
i'm not a machinist or anything, but i could see that leading to erosion. it looks about as deep as the metal sealing surface around the cylinder. i personally wouldn't feel comfortable putting it on that way. especially with the way i drive :bashtard: :wink:
 

·
Registered
Joined
·
6,611 Posts
I agree with Cuatro. That would take 5 seconds to fill with a spool gun, and 5 minutes to dremil down and no one would no better.

Hank
 

·
Registered
Joined
·
17,178 Posts
hey, also, what was used to smooth the combustion chamber? and hows the process go?
 

·
Registered
Joined
·
3,280 Posts
Discussion Starter · #6 ·
derek-

just used a small wire wheel on a dremel, takes about two minutes per chamber. Takes all the large granuals from casting off real nice. did the same with my exhaust ports after i port matched them.

hank- what's a spool gun? i'm kinda new to a lot of this.....i was planning on just jb welding it up...but i'd rather weld it or something.....
 

·
Registered
Joined
·
17,178 Posts
yeah, it's the welding trigger with a spool on the back of the handle. i guess they are more portable or something?
 

·
Registered
Joined
·
3,280 Posts
Discussion Starter · #9 ·
yep you're right derek, my machine shop is gonna hit it with a little weld before they machine the gasket surface. They said those clean up real nice....nothing to worry about.
 

·
Registered
Joined
·
6,611 Posts
Yea, a spool gun is just a glorified MIG. THey are handy for Aluminum, becuase they don't run in a sleave to be contaminated like a standard MIG, they intstead have the spool on the handle, so no contamination occurs ideally. It just goes from the spool into the tip...They are really nice for alum. I can't wait to mess around with some intercooler stuff.

I was sick of dealin with stupid Heli coils in my head so i just filled em up with the spool, and retaped them. They work great now. That chamber should literally take a few minutes and it will be super strong.

HANK
 

·
Registered
Joined
·
17,178 Posts
hey hank, i'm just curious, i know that when you weld aluminum or heat it up it becomes annealed, and really soft ( i know from trying to tap a hole in some aluminum after it was welded) how did you get around this? maybe i'm missing something here.
thanks,Derek
 

·
Registered
Joined
·
6,611 Posts
yea Derek, Try looking for different Filler. I forget the official numbers, but the standard filler that everyone uses, is softer for easier pudlin. Its really easy to weld with, but is rather soft. For stuff like Radiators and IC, its great. But looks for the harder filler that people uses when makin frames and whatnots. Ask a weldshop. they'll hook you up. Its a tad more expensive, and welding with it is just a tad harder, but its stronger.

HTH Ill look up the filler numbers for ya

Hank
 

·
Registered
Joined
·
31 Posts
Derek,
This isn't always true. Annealing is a process of de-crystalizing the metal and is usually done below the melting point, for instance with a sooty flame. Different alloys respond differently to different heat applications. In some instances the weldment may be harder than the original metal. Castings are typically soft by nature anyway. 4043 which is the general purpose aluminum rod should be suitable for most castings and will provide good color match as well as strength. 5653 is the second most common rod and has a higher tensile strength, but is used primarily for 5XXX series alloys, where anodizing is to be done, or where salt water exposure may occur. Hope this helps.
 

·
Registered
Joined
·
17,178 Posts
ok, thanks. i haven't taken welding courses yet and don't know much about metalurgy, but i want to learn about it and hope to be able to take welding classes one day.

on the piece that i was talking about that i had a hard time with because it was soft, that was within about a half inch or so of where the welding was done. so it just basically got heated up, not the actual weld was i trying to tap. maybe that's why i had a hard time?
 

·
Registered
Joined
·
11,662 Posts
You can't decrystallize metal unless you liquify it, or vaporize it. Once it solidifies, it becomes a crystalline structure again. Fuzzy areas are the solidus/liquidus lines in a phase chart. All solid metals are crystalline structures. Annealing just reorganizes the crystal matrix. Sort of like strain hardening, controlling cooling, all the various heat treatments, etc all change the matrices.
 

·
Registered
Joined
·
31 Posts
Eric,
I stand corrected, but I think the gist of the post remains intact. Annealing usually entails bringing the metal up to a specified temp. below it's melting point. Welding melts and recrystalizes usually resulting in a harder matrix than something which has simply been annealed. Decrystalize was the wrong term, annealing just scrambles the molecules a bit.
 

·
Registered
Joined
·
11,662 Posts
Just didn't want people thinking the wrong thing ;-)

For structural welds, it should be normalized afterwards due to the heat affected zone. The welded area can be stronger depending on the filler, but the area immeadiately outside of that tends to be weaker than the non-welded materal...
 
1 - 17 of 17 Posts
Top