Secondchance - 380 build begins!

[secondchance]

Originally Posted by Toni94ZR1

Hi all from Barcelona (Spain)
Thank you Yun. Very complete thread on how to build a 380 LT5 .
For dowse of us overseas very useful to find parts for 380 upgrade.
As I would like to have all the technical spec to know if I could do the offset crankshaft grind to 2" here in Barcelona, when you said "heat treat and index" what do you mean? Once the offset rod pin are done need to do a heat treat on each rod pin ? What do you mean index the crank?

Thank you guys !

Hi Toni,

Didn't mean to ignore you. I must have missed your post.
Heat treat is, after regrind, heat/cooling process to harden the surface. I am no expert so I am pasting an excerpt.

"The typical heat-treating process for carbon-steel alloys is first to transform the structure of the rough-machined part into the face-centered-cubic austenite crystalline structure (‘austenitize’) by heating the part in an oven until the temperature throughout the part stabilizes in the neighbourhood of 1550°F to 1650°F (depending on the specific material). Next, the part is removed from the heating oven and rapidly cooled ("quenched") to extract heat from the part at a rate sufficient to transform a large percentage of the austenitic structure into fine-grained martensite. The desired martensitic post-quench crystalline structure of the steel is the high-strength, high-hardness, form of the iron-carbon solution. The rate of cooling required to achieve maximum transformation varies with the hardenability of the material, determined by the combination of alloying elements.
Distortion and induced residual stress are two of the biggest problems involved in heat-treating. Less severe quenching methods tend to reduce residual stresses and distortion. Some alloys (EN-30B and certain tool steels, for example) can reach full hardness by quenching in air. Other alloys having less hardenability can be quenched in a bath of 400°F molten salt. Still others require quenching in a polymer-based oil, and the least hardenable alloys need to be quenched in water. The shock of water-quenching is often severe enough to crack the part or induce severe residual stresses and distortions. As the hardenability of a material decreases, the hardness (thus strength) varies more drastically from the surface to the core of the material. High hardenability materials can reach much more homogeneous post-quench hardness."

Indexing, as I meant, was spin balancing of the crank shaft to minimize any imbalance when spinning.

These procedures are what was recommended by the shop and those who know how to build high performance engines.

[secondchance]

Originally Posted by SAM/CH ZR-1

I've got a question:

What gap are you using on piston oil rings?

Sam

I'll find out. Short block was assembled by an engine builder at the machine shop.