Hi Temp damage
 

Before hitting the scrap pile does anyone know what temp would compromise a cast iron block and the same info on cranks, I've got both flathead and model B cranks involved. Never had any water put on them and were buried so they cooled real slow. Spark test? Rockwell files?

Re: Hi Temp damage
 

A good question for a metallurgical engineer. I am sure it would help a lot if you knew the alloy composition of the block and crank. A metallurgical engineer could prepare a small speciman of each and tell you their current state of composition based on microscopic analysis of their carbon content and the Iron Carbon Equilibrium Diagram of heat treating. Time, temperature and transformation during heat treating are super critical. Here's a good article.
http://www.epi-eng.com/piston_engine...ign_issues.htm

Here's another;
https://www.ductile.org/didata/Secti....htm#Annealing

Re: Hi Temp damage
 

I would think you would have to be talking very high temps to be an issue.

Re: Hi Temp damage
 

What I would do is to see if there is any warp-age before I would worry about metallurgical damage.

Re: Hi Temp damage
 

Good points.
How long and at what temperature were these items "cooked". Was it a garage /car fire?

Re: Hi Temp damage
 

If the pistons are melted it probably got too hot, if the bearings didn't melt the crankshaft is probably good

Re: Hi Temp damage
 

It got hot enough to put the piston skirts in in the pans and turn a set of edelbrock flats into a puddle. All of it sat under a 3 ft layer of ash for a couple
off weeks. I also had an old braze repair disappear out of combustion chamber as well as some brass plugs.

Re: Hi Temp damage
 

How about dimensional stability? Are the cylinder bores till round? Are the deck surfaces and pan rails still flat? Valve seat inserts still tight? Are cam and crank bores still straight? If the answers are yes, I'd say it's rebuildable (if no cracks!). Same for the cam and crank.

Re: Hi Temp damage
 

I've seen an unobtanium engine block heated up to dull red in order to do fusion welding on them. The old Duesenberg and Marmon engine blocks are well worth repairing if they crack.

The key is whether it was either warped or whether it has cracks from cool down. If it can be machined flat and round with little effort wherever it counts then it should be usable. I'd find a way to pressure test it first and go from there. Flatheads like to crack.

Re: Hi Temp damage
 

I would think firefighters spraying large volumes of cool water to put the fire out, which found their way onto hot iron, may have created more of an issue than the actual heat build-up of the fire.

Re: Hi Temp damage
 

>>> Never had any water put on them and were buried so they cooled real slow.>>>


Blocks prolly OK. I agree with Kurt on the crank. Jack E/NJ

Re: Hi Temp damage
 

Bake cleaning is around 500 degs. Doesn't seem to bother the blocks, or anything else.

Re: Hi Temp damage
 

If it got hot enough to melt the heads off of it and the piston skirts, then it got pretty damn hot! I'd have the block cleaned, magged, inspected for warpage, etc.. Given that it was under a pile of stuff, it probably cooled back down rather slowly. If water was sprayed on it while red hot - who the heck knows. Had to be one BIG fire for that level of heat to build up. Maybe it wasn't put out at all . . . and just burned to the ground . . .

Re: Hi Temp damage
 

This chart shows melting points of various metals.
https://www.steelforge.com/literatur...elting-ranges/

Here's some excellent reading on the warping of engine blocks. It seems that fr the block to actually warp it must be heated to an extremely high temperature. There is no doubt that the deck surfaces must be checked first.

https://www.google.com/search?q=does...hrome&ie=UTF-8

Re: Hi Temp damage
 

It´s not so much about max temp when it comes to cast iron.
Controlled heating and cooling is what sets the structure of it.
Even in a bakeoven you have a slow temp rise then hold that temperature for a while and slowly let it cool down again.

Re: Hi Temp damage
 

Based on the chart supplied by 19forty I would say that the cranks and blocks were exposed to around 12 to 13 hundred degrees. Even if the blocks were blueprint straight what would that do to the future machinability of cast iron and the strength of the existing threaded holes

Re: Hi Temp damage
 

If it was under a pile of loose ash, it cooled down, very slowly and will now be in a annealed state. Not a bad thing for cast iron.

As RotorWrench states, you can successfully weld cast iron by heating it to it's critical temp (the whole item not local) and then slow cooled (anneal). Heads have been repair that way for a 100 years and is the best way to do it.

You don't hear about blocks repaired that way, because it takes a large furness to heat them. It hard to find someone to do heads that way, in our "modern times"?

Like has been said, I would inspect the for cracks and then pressure test but, it sounds like there is a good size crack with the " I also had an old braze repair disappear out of combustion chamber" comment.

As for the cranks, have them checked for straightness and what ever hardness std applies and regrind if possible.

PS
Where are you in Nor Cal?

Re: Hi Temp damage
 

i've had blocks spray welded at crow cast welding and he bakes them in an oven to 700 degrees to start welding. its on a cart on rails going into the oven. the area that is being repaired is hotter due to the weld, and the iron will move in that area and need machining. the rest of the block doesnt change. red heat is about 1500, aluminum melts at about 1200

Re: Hi Temp damage
 

The braze that dropped out was a tunnel fire ignition fix and not a crack. I was in Paradise but now in Chico. I guess the question would be what were the Ford specs for Rockwell hardness ?