At what time do you think to add mains?

I was wondering at what point do you add new mains in a 440 motor? Looking to put a Source 512 kit in my 440, is it necessary to add new aftermarket main caps? I know its a good idea to have them but do you really need to. Thinking Compression will be around 12.36 to 12.00 depending on the heads I use.

You might want to move this to the race section. I would say it depends on rpm. Keep it under 6000 and stock caps should be OK. Main studs with a line hone would be extra insurance. Approaching 7000 rpm and steel/aluminum main caps are suggested.

Adding aluminum mains can be an expensive proposition as almost are bored for LB motors which have smaller mains (the 440Source ones are). This means they need to be align "bored" before align honing. Finding someone to do that is not as simple as finding a shop that does align honing. They also will likely need to be milled slightly to fit the registers so again you need a shop with a mill. If you're pushing this motor to its upper limits all the time or if money is no object then you should probably go for it, otherwise stick with the stock caps and studs.

Having just done a 440 based stroker I can tell you that in hindsight I should have done it with a 400-based block - you have bigger bores to start with so don't have to overbore as much to achieve the same c.i. and the aluminum caps can be installed with less hassle. Not to mention the weight savings! And 400 blocks have better support in the main webs.

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Adding aluminum mains can be an expensive proposition as almost are bored for LB motors which have smaller mains (the 440Source ones are). This means they need to be align "bored" before align honing. Finding someone to do that is not as simple as finding a shop that does align honing. They also will likely need to be milled slightly to fit the registers so again you need a shop with a mill. If you're pushing this motor to its upper limits all the time or if money is no object then you should probably go for it, otherwise stick with the stock caps and studs.
Not to mention the weight savings! And 400 blocks have better support in the main webs.

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No weight savings in most 400 blocks versus 440 blocks I have weighed a bunch of the(12 to 15), maybe 5 lbs(215 to 220 lbs) differences between both B and RB, no patterns on one type being lighter than the other I have built several Mopar strokers over the years, B,RB, Hemi, and SB, aftermarket main caps can't hurt in a motor that may see some detonation I agree on using a low deck to start with, I like them