I am playing with many mods and it appears that MC crashes with what im guessing incompatabily issues with another mod in 1.7.10.I attach my crash log here (pastebin didn't seem to work at all)
crash-2017-05-12_20.49.10-client.txt

I have no idea why you posted that here. The first lines of the crash are

java.lang.ArrayIndexOutOfBoundsException: -1
	at net.minecraft.potion.Potion.<init>(Potion.java:68)
	at blusunrize.immersiveengineering.common.util.IEPotions$IEPotion.<init>(IEPotions.java:92)
	at blusunrize.immersiveengineering.common.util.IEPotions.init(IEPotions.java:32)
	at blusunrize.immersiveengineering.common.IEContent.init(IEContent.java:508)
	at blusunrize.immersiveengineering.ImmersiveEngineering.init(ImmersiveEngineering.java:99)

Go post this at the correct repository please, but do not expect much help as Minecraft Version: 1.7.10 is now E.O.L. for Immersive Engineering and most other mods.

@Xxepic-gamerxX Go to https://github.com/Blusunrize/ImmersiveEngineering/issues/new

well thx...yea i dont understand much code...i only posted here as the report said the railcraft errored but thanks anyways