400 crank,Comp ratio

[73Dustbuster]

Does anyone know if a 400 ever came with a steel crankshaft if not how do I tell what kind of crank it has. And does anyone know how to tell what your compression raito is.(on a rebuild someone else did,so they said (if you know what I mean)).
One last thing what would a 400 be at 40 over thank you .

[Doug Wilson]

I think I just read on another forum that 400 truck engines had drop forged, steel cranks - by the way ALL the cranks are steel - some are forged and some are cast, but they are ALL steel. Forged are ultimately stronger, but cast are inherently better balanced. Ask any engineer who understands both processes. If you go to Edelbrock.com, then to their "Tech" section, you will find all the formulae you need to make the calculations you are looking for.....this from Doug

[curious]

what about nodular iron cranks? is iron same as steel?

[Doug Wilson]

No such thing as a "nodular iron" crank in any kind of automotive engine. Nodular iron could be in rear axle(housings only - 9" FRoods particularly), also could be in heads or blocks. There is simply not enough strength to make it into a crank. Now....I'm being technical here, so slang terms that everyone knows what they are, will be used forever - like"steel" crank to mean "forged steel" crank. And maybe, "cast steel" crank is called "nodular iron" in some places, but, believe me, there are no real "nodular iron" cranks.

[PRO]

Yes there were forged steel cranks for 400s in 1972 hp motors and possibly some early production 73s,youll have the thin balancer if its forged.A cast crank is adequate to about 450 hp.As far as compression these #s are in my long term memory,a 0 deck piston in a .060 over 400 with .020 thick head gaskets and 78cc heads gives you an 11:1 although all 400s were 8.5:1 comp with pistons approximately .140 down the hole.A .040 over 400 gives you 408 cubes.Forging is a heat treatment,by heating the crank to a very high temp and slowly cooling it the strength of the steel is increased,hope this helps..........PRO.....

[Doug Wilson]

Forging is doing the final metal processing by taking the material in question, bringing it to a very specfic temperature, and then smacking it multiple times into a die with a great big steel hammer. This causes the grain in the metal to align and increases its' strength. This is why a forged crank is not as inherently in balance as a cast crank. Forging is more like a 2 dimensional process, and casting can produce more accurately located counterweights. PRO is referring to "heat treating", which, when done properly, can increase the "toughness" or "hardness" of a material. Sorry to be nit-picking.