Filling bolt holes in cast iron

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jungspike
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Filling bolt holes in cast iron

Post by jungspike »

Bought a T3/T4 manifold only to find out that all the mounting extend into the manifold, so when u bolt on a T3 turbo, all the exhaust exits the T4 holes. Freaking stupid design. I just got done welding exhaust, so I would like to salvage this part. Any ideas how to seal the holes? I have never welded cast iron, but I could put in studs, cut then smooth and weld them so the dont rattle loose. If I buy a T3-T4 adapter (smallest I saw is 1.5 inches, it will put the turbo so high it will touch the hood. I could buy a new manifold, but that will mean redo-ing the downpipe.

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jungspike
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Re: Filling bolt holes in cast iron

Post by jungspike »

I think I am gunna try to put in a stud with the wrong threads and cross thread it. Then cut it off.
modulation
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Re: Filling bolt holes in cast iron

Post by modulation »

Yeah that thing would take TONS of heat to be able to weld, 220v welder no question. You'd want to preheat the whole thing as much as you can before trying to weld it.

I like your idea of putting in a stud cross threaded and then cutting it off. Maybe tack weld it on the top in a couple of places per stud and then grind down the tacks.
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Alonso
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Re: Filling bolt holes in cast iron

Post by Alonso »

It'd be cake to fill in the holes with a Tig welder. I'd use a filler rod with a high Nickel content.
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i_slide
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Re: Filling bolt holes in cast iron

Post by i_slide »

I've put this same manifold on countless budget builds. What I do is get a bolt that threads in with locktite then take a whiz wheel to it which makes it level with the manifold. I use the metal gasket then bolt the turbo down. The studs never back out because the turbo flange actually covers about 1/4" of each hole. With that in mind though, take your time and do it as level as possible so you don't have the risk of blowing gaskets out on a monthly.
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erich
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Re: Filling bolt holes in cast iron

Post by erich »

Your best bet is to braze it,
Preheat to 400F or so then fill with any brazing rod, wrap with a welding blanket to slow the cooling.
Once down to room temp grind it flush.
If you melt the cast iron (when you weld, not braze) the high carbon in the material forms extremely hard nodules that crack when they cool. Using a high nickel rod helps (because nickel is soft) but if you can preheat the manifold to a high temp (400F+, higher is better) so as the weld solidifies it takes a while to fall to the preheat temp it allows the cast iron change the grain structure back closer to the cast state and will resist cracking better.
No matter what you do make sure the thing is preheated and wrap when done to allow it to cool slowly.
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