Anlushac11":18fpoged said:
Called to see about getting injector bung holes drilled and getting bungs welded in or alumium bungs epoxied in.
No one wants to touch it. The two pro race shops dont even want to work on cast iron.
Here is my take on why most shops decline iron welding jobs.
Cast iron's composition does not lend itself to welding. A view of the Lincoln Electric knowledge section (search engine terms: "weld cast iron") notes the following:
1. Cast iron is difficult, but not impossible, to weld. (These are usually repair welds, due to casting or machining defects, not usually joining one part to another.)
2. Because of the nature of cast iron tiny cracks tend to appear next to the weld even when good procedures are followed. If the casting must be water tight, this may be a problem. Some sealing compound may be used.
(Source:
http://www.lincolnelectric.com/knowledge/articles/content/castironpreheat.asp)
Fuel injectors have at least tens of pound of pressure. So any welded iron joint will be under more than just the normal pressure of liquid flow. Combine that, the other information above about small cracks, with flamability of gasoline and we have the reason why shops decline the work.
We are all frustrated with the poorly aspirated log, but of course prefer reliable, safe engines.
I looked into other possibilities.
First, I thought about casting aluminum parts tapped to screw into a complementary surface made into the log. Possibly the injector could be snugly "sleeved" into the aluminum part and the aluminum part screwed into the log. (Apparently, under normal conditions, dissimilar metals cannot be welded.) Since aluminum expands more than iron the aluminum fitting's expansion into the iron log might improve under operating temperatures.
But there is still another option. One can also cast iron. It has a significantly higher melting point than aluminum, but it can be done. (Search term: melt iron Chastain)(Another term I found useful is "David Gingery" -- of the DIY machine shop build).
The TBI/Tempo solution is interesting, but given the versatility and power of a computer system like MegaSquirt, I started looking at addressing the log.
Certainly replacing the log with the CI or Aussie versions are possible. It's just that I am not a bolt-on guy. Nor very handsome.