I was putting bigger valves and porting some SBF heads E7's and cut through the back of the valve pocket at the bottom near the valve guide. I already have a lot of time in the head and hate to start over . any tips for welding this up I have both tig and stick welders. Over the years I have had mixed results welding cast iron with nickel . I was thinking of preheating the head in a large kiln that I have, brazing with a torch or stick welding it with nickel then having it pressure tested. suggestions appreciated.
I had a cobra jet head with the same problem. Took it to a local pro welder. He heated the head in a oven before welding up the problem area.
If you are any good with the Tig I would look into 308 rod or some silicon bronze filler. I find for better quality cast iron 308 rod works better than 99% nickel. I save the nickel filler for "dirty" cast iron. By dirty I mean lots of impurities in the metal, not surface prep. Your surface prep needs to be flawless, use a carbide Burr to remove the top layer of metal around the whole area to insure you won't introduce grinding grit or other metal from your grinding stone into the weld. Pre heat a couple of hours if you can, to make sure all of the casting is up to the same temperature. Peen the weld and then cool as slowly as you can either by returning to the kiln or covering with sand for 24 hrs.
To do it...right... You need to heat the whole head weld with high nickle wire, re-machine all surfaces. Some have tried and succeeded, most have tried and failed using various methods. The "best" (hate that word) way of doing it is noted in the second sentence above. Using other methods, might work for a day, for a week, maybe even a month of daily driving, but I think most will say, eventually...the weld will fail. I've done similar...I just started over on another head, no matter how much work is on it/them..! Mike
I had a friend use a product called Defcon it is used to repair jet engines in the military. it sets so hard you can machine it. it says so on the instruction box. R G S
I am pretty good with a tig, I just don't see as well as I used to Where the hole is, it easy enough to get the tig torch in the valve pocket. I like the idea of silicon bronze filler with heat control of the tig. would seem to be the cleanest and lowest temp solution. think I will give that a try and see how it turns out. getting the head up to temp and cooling it slowly is not a problem at all with the kiln. preheat to 600F sound about right ? It will be my daily driver so I am a bit concerned about a lasting repair. When I searched the subject I did find torch brazing to be a popular fix , no mention of longevity or failures though.
Yes sir you are correct but it has only been 51 years ago I read the label while I was in the air force. But hey I was close for a old man who suffers from CRS .........
I thought Defcon was used to repair cast aluminum only... We used that stuff some years back to repair prototype aluminum castings....
If you have a Rockmount dealer nearby give him a call. I had some of their tig rod for cast iron in the 90's that was amazing. It was not much different than welding steel. Smooth and ductile and soft enough to file or mill. It was quite expensive, but I never came across anything I couldn't fix with it. Don't recall the name or number they gave it, but your dealer will know right off.
We had one of these at work for repairing shafts that were worn. They would be machined when finished. The small bottle of powder on the torch contained the type of metal you were going to repair. I was thinking of getting one for home use about ten years ago and I think the cost was about $250 and of coarse the powder was an additional cost. The machine shop in my town has on of these. https://www.bing.com/videos/search?...A45AAF3A8A46E5A0A3DDA45AAF3A8A46E5A&FORM=VIRE
Yes it would have made more sense to get a set of gt 40 heads of even a set of aluminum aftermarket ones. My time could have been of better use doing other things,I have a bridgeport and the tooling for guides and hard seats . The heads were cheap and I enjoy making chips.
The only reason to repair a cast-iron engine part is because you can't find a replacement. Deuces is right, there is no viable reason to spend the time and effort porting a set of E-7's when GT-40's are readily available.
Very interesting site. I'll be going back to it for reference on a couple projects I'll be working on. Thanks for posting. Ed
cool video thanks. I have one of those for hard facing, never thought of using it for welding cast though . the manifold in the video reminds me of one I welded up for a friend ,the manifold was on back order forever. the manifold was spider webbed with cracks and fell in pieces when he took it off the car,I bolted it to a 1/2 steel plate and burned about a pound of nickel stick rod into it . he drove the car another ten years then sold it never cracked again or leaked. I have welded things that didnt look as bad and didnt turn out as well. never know with cast iron.
You won't need to pre heat nearly that high if you are using silicon bronze. I think 200-300 would be just fine. I would plan on having to deck the head afterwards, things may move around because of the heat cycle. If you have never used silicon bronze before practice on some scrap cast iron before you try the head. I find the less I melt the base metal the better.
No arguing over your point of view I guess.... I love making chips also.. I do that for a living... Enjoy!..
Nobody said, nobody asked, or I missed it. Intake or exhaust? If exhaust, what about machining and setting a seat that goes deep/secure enough? Combustion temps are as high as 1200 deg. How hot do we think that exhaust will get? Just a bit of brain food...
thanks for the link, its at the bottom of the exhaust valve pocket ,pretty far from the seat. there is coolant behind it . imagine an aluminum head would melt if the port got that hot, I have heard that lead is used in some heads to fill the thermactor holes and crossover passages without issues.
The Jalopy Journal
