Not that I know of, Welding cast iron is very difficult and theres not a whole lot of people who can do it correctly, my thoughts would be what if the weld breaks?

 

is it possible to weld up combustion chambers to increase compression ratio?

X-41 pure nickel rod adheres very well to the cast iron that heads are made of and is machineable, has anybody ever done this before?

Augusto.

Welding cast iron is tricky and usually not successful. The problem is that cast iron is quite brittle. When heating it locally such as welding, the material in the area of the weld greatly expands while the surrounding cooler material doesn't expand as much. This builds in a lot of stress which usually exposes itself in the form of cracks that form as the casting cools.

Extensive pre heating (800 F/427 C) of the casting and extremely slow cooling, like a a day or two, will crowd the chances of success on your side, but are no guarantee.

Cast iron isn't the greatest material for operational heat transfer, my experience in combustion chamber redesign showed that you need to keep coolant no more than a quarter inch (6-7mm) from the combustion chamber surface or local overheating will occur leading to detonation. This often requires machining a pocket into the cooling passage below the weld to insure coolant doesn't become too isolated from the flame heated surface.

You could look into these guys, I haven't used their stuff but they advertise a way around cracking problems http://www.muggyweld.com/index2.html

 

is it possible to weld up combustion chambers to increase compression ratio?

X-41 pure nickel rod adheres very well to the cast iron that heads are made of and is machineable, has anybody ever done this before?

Augusto.

I weld cast heads and blocks with two different methods. one is with the nickle rod the other is with sylicone bronze. the trick to doing this is in the pre heat of the part, and controlled cool down. sam-missle

 

Sam, what is your total procedure when welding on heads and blocks? I've got a set of heads that I want to weld up the heat riser passage on. A friend of mine says he cooks them in his woodstove for a few hours then does his welding then back in the stove they go but he never mentioned cooling them down slow- hey maybe he leaves them in the stove till the fire goes out. I've also heard a barbecue grille can be used for preheating. Looking forward to your recommendations, Bob

 

I've also heard a barbecue grille can be used for preheating.

Ayuh,..........

I've done it that way,.....
In my case it was cast iron Exhaust Manifods for a boat that had been Freeze Cracked.....
After it's Prepped,....
Put the piece on the Grill, on High,+ let it Heat for a 1/2hr. or so,......
Open the grill hood,+ weld a 1/2",+ put it back down,... Let it cook....
Give it 3 to 5min.s,+ Do it Again....

Once the welding is Done,.......
I put it into my kitchen oven, preheated to the Max,+ bring it Down 50° per hour..........

Probably alittle Excessive,..... But I've never had a Crack from welding this way.......

 

Sam, what is your total procedure when welding on heads and blocks? I've got a set of heads that I want to weld up the heat riser passage on. A friend of mine says he cooks them in his woodstove for a few hours then does his welding then back in the stove they go but he never mentioned cooling them down slow- hey maybe he leaves them in the stove till the fire goes out. I've also heard a barbecue grille can be used for preheating. Looking forward to your recommendations, Bob

For this just pour melted aluminum in the hole, its pretty easy. You can make a small charcoal blast furnace in a flower pot, and melt an old piston in a small skillet.

 

For this just pour melted aluminum in the hole, its pretty easy. You can make a small charcoal blast furnace in a flower pot, and melt an old piston in a small skillet.

this, i would like to know about.

 

I think you might send 'em to Sam-Missile.

There are 'spray welders' for doing this type stuff too. Don't know anybody that does it though. Seems I've seen some heads that ate valves and were done this way, on one site or another.

 

One of the reasons that cast engines and heads are hard to weld on, is the fact that they have a vast amount of impurities, ie. sand, that is left in the pores of the cast. When you put "heat" (weld) to an area the sand particles explode and cause small craters, hence, poor adhesion of filler rod, crystalization of base material, etc. Another reason is contamination of oil, carbon and gas additives to the porous cast iron. These are just a few reasons why cast combustion chambers are not welded to increase compression.

Repairs to cylinder heads due to cracking are generally repaired by the pinning and welding method. This is the method where you would pin across the crack, gouge out the crack to new clean bare metal, and add filler rod to rebuild the area. This process allows you to bite in to new metal (steel pins) and clean block iron. Still not the best way, but it will get you by till you can buy a new head.

 

Cylinder head welding;
Here and here

 

interesting, please keep adding thoughts.

I have repaired cracks and welded cast iron succesfully for years, the key to it is keeping the piece hot, very hot while welding and then cooling it very very slowly, part submerged in hot sand is a great way of cooling, also a bit of hammering the weld beads help a lot relieving stress while cooling, nickel and bronze adheres very well to cast iron if well prepped and clean.

asides from the regular "buy new heads" advice I would like to know how did you guys raised compression back in the hot rod heydays where there were no trick parts available off the shelf.

Augusto.

 

that's the way we usually do with 4 cylinder inline engines, but for V8's I don't really feel like milling the heads because of the geometry alteration that must be corrected with the intake manifold, a lot of machining trouble, that's why I'm thinking of welding up the heads, wich by the way I have done to aluminum heads succesfully.

Augusto.

 

yeah. but cast iron is not aluminum.

 

pre heat

I remember a guy in 1952 who heated up a block in his brick backyard
bbq and added steel webs and brazed it, added a lot of metal ..then let it slowly die down for one more day, added a little charcoal to controll the cool down rate . then machined the block for a stroker crank . slow pre heat and keep above critical temp while welding then slow cool down

 

Can you weld the chambers to make them smaller? Yes and no. Setting aside the difficulty in properly welding cast iron, there's a bit more to it than that. Engines are very sensitive to combustion chamber shape and size, and without testing the shape, you could end up with poor performance caused by detonation, poor swirl, and a host of other things. Aftermarket heads that could easily out perform the ones you have can be had for less money than it would cost for the welding, machining, cc'ing of your current heads. Do yourself a favor and spend the money on better heads. You won't regret it.

Mark

 

Augusto I'm assuming small block parts don't grow on trees in Ecuador . So flat milling or a domed piston would be your best bet if the manifold corrections for angle milling are hard to get done there. Also while high compression is nice sometimes it just ain't worth the trade offs to get it. Is the import situation such that you could order parts stateside and have them shipped reasonably?Any buddies in the U.S military? They can get them shipped in easily.

 

custom's duties are quite high here making importing performance parts a luxury, freight is also expensive for heavy parts like heads.

I like rising compression because I live at 6.600 feet of altitude and squeezing the mixture a bit more helps a lot, seems like domed pistons may be a better idea, they cost and weight considerably less than a pair of heads.

Augusto

 

I believe that would be your best option.