I just read the article about how to make a 500 horse LS1. I am a little lost when it comes to cam swaps. I think it would be really easy to mess up the timing. Is it difficult to get the engine back in time?

 

It is fairly easy to get the timing back to where it was the with stock cam when you install a new cam on any engine, LS1 being no exception. The cam has a spocket on it for the timing chain. It has an indicator mark that isto be in a certain position (say straight down) then a mark on the sprket on the crank is in a certain position. You simply make sure the marks are in the correct position (this varies slightly from one type of engine to another, but there is always a way to line up markers according to the shop manual.

This gets the cam about in perfect, stock timing. You can buy special aftermarket chain sprockets for the cam that allow you to make very small, very precise adjustments to the cam timing after it is installed (of before). You install the cam, then you can turn it a couple of degrees either way relative to its base location. This is called "degreeing" the cam. If you advance it (all valves opn and close a little earlier, you supposedly (and sometimes do) gain some power. If you retard it, you sometimes gain some power at different RPMS, etc. Or you may want to make sure the itming is exactly on (the marks on the sprocket might by half a degree off, etc - production tolerances and all. But this is a detail for real experts with all the equipment (frankly its hard to tell with typical "garage mechanic" type tools if the cam is within about a degree or two of where it ideally should be) and you also have to be very careful for valve clearance reasons.