I am new to the ls series motors. I have a question regarding the rods. I am considering boring my 5.3l lm7 to a 5.7 (cast iron block). If I am reading things correctly the stock rods are 6.098" Jegs offers a forged ls1 rod at 6.100" How much difference really will there be in the extra 0.02"? Is there going to be a clearance issue? If I do this I plan on using forged components in the bottom end.

 

Not much difference at all. You'll just have your pistons stick out 0.002 more out of the hole which is negligeable. At worst, you can have a machine shop take 0.002 off the top of the pistons if it bothers you that much or if you end up with too much out of the hole.

 

So I assume I wouldnt really know if anything is going to "hit" until I put the heads on and crank it over by hand? I would assume there would be enough toleerance between the heads and block to allow for this.

 

Don't think 2 mils are going to cause that. Probably the real question is what is the difference in weight?

 

Every single LS engine I have taken apart and measured, the pistons stick out of the hole.

I believe the lowest I have ever measured was +.005 out of the hole. I believe the most was +.011 out of the hole. Between +.006 to +.008 is usually the most common.

A factory MLS gasket is around .052 Thick compressed, the early carbon type gasket is around .060 compressed. As long as you don't exceed .035 of quench you should be just fine.

The only way to know for sure would be to assemble it and check. If need be you can order a taller gasket. At this point I doubt .002 will affect your overall build plans Forged pistons are usually built with rod length factored in.