I am getting ready to plastic gauge the mains and rod bearing clearances on my LT1

My Helms manual shows two sets of clearances one is "production" and one is “service”

Not sure what this is? I am assuming production is when the engine was brand new built and service says how much clearance can go but if you look at the numbers below on some clearance production are tighter and some clearances service are tighter so my theory does not make sense.

MAINS
PRODUCTION
#1 0.0008 TO 0.002”
#2, #3, #4 0.0011 TO 0.002”
#5 0.0017 TO 0.0032”
SERVICE
#1 0.001 TO 0.0015”
#2, #3, #4 0.001 TO 0.0025”
#5 0.0025 TO 0.0035”

Anyone know specifically what this is?

Also what main is #1 I am assuming the main at the harmonic balancer??


Thanks

 

I tried to keep my tolerances with the new bearings like I found the old ones. However, with the new bearings they ended up just a hair looser. If I recall, #1-4 was around 0.002" and my #5 was in the 0.0017"-0.002" range when I got done. I bought some standard, some undersized, then mixed and matched until I got what I wanted(going no greater than 0.0005 larger on the bottom shell).

Here are some of my threads on my issues....The first one has pics of where I used plastigage on the stock bearings and I show the clearance values(both mains and rods).

https://www.camaroz28.com/forums/lt1...ctures-713070/
https://www.camaroz28.com/forums/lt1...arings-746672/

Here are some snap shots from my 1996 factory manual....shot 003 has the "production" vs "service" tolerances.
Index of /1996_Z28_Factory_Manual_Snapshots/LT1_stock_specs

Not sure why, but having trouble with my online storage.....may not be able to get pics until it's resolved. Edit:We ended up moving some server space around, so my pictures and such may not work until the domain updates happen.

 

You are correct, the #1 main is at the pointy end of the car.

 

Thanks.

Forgive my ignorance but why is there a reference to "production" and "service" in my manual?

 

Not sure if you have seen my snapshots yet. I'm moving my webspace around and it is in the middle of resolving to another nameserver(www not work right...points to old stuff..which is an empty directory). I've been having trouble with it, but this should get you to the shots....

http://ace1252.com/1996_Z28_Factory_...1_stock_specs/

The only thing I can add to the production vs service thing is that they wanted the tolerances tight from the factory.