[mudder81573]

In the planning stage for a 406 ci sbc with a 300 shot. I am going with a aftermarket block. As the title says, which mains?

 

[BEDNAR1320]

I like the 400 mains because there is more "overlap" with the larger mains on the crankshaft-that is more material between the main and rod journals with the larger mains.

 

[chaz6966]

i was wondering the same thing, why do so many people seem to go with the 350 mains. 400 is a larger diameter which you would think would make the crank stronger/ more stable.

 

[10.90streetcar]

I went with 350 mains. Less bearing surface = less friction. But i'm making less than 900 hp and spray only 100 to 150 on top of that.

 

[motormanic]

it all depends on how much power you want to make and how you want to make it. Smaller mains will give less friction but going to the 400 main size does not always mean a stronger crank. thats up to the crank maker.In my opinion, if your buying an aftermarket block, dont get cheap and buy a quality 350 main crank

 

[Horndog]

How much HP are you shooting for on nuts ?
If you want to help the overlap when using the 350 mains, go with a 2.0 dia rod pin.
As was said above, regardless which main size you go with, invest in a quality crank.

 

[69chicken]

350s on mine shooting for 1300H.P. using a 500 shot. I went with the best crank I could $$$$$.

 

[Bad Influence Racing]

The very small difference in size won't due much for overlap and with a 3.750" stroke will do nothing. More benefits to the smaller though, as stated, less bearing speed, friction and heat. My rule of thumb is keep overlap to 2" and under from main journal to stroke. Like Horndog says, you can help some applications going to the smaller rod journal, which in effect does the same thing as the mains and has the same benficial effects. I run 350 mains on just about every small block engine. Only time it will be critical is passing that 2" rule of thumb. The aftermarket blocks also use the same caps for either main, and although the caps are real strong, are stronger when using the smaller diameter main size. The 400 main removes more material from the same cap. Hope this helps.

Oh and x5 on running good cranks, but again the overlap is not that drastic in these, so power and application should tell you what material crank to use, not the overlap in this case.

 

[colo cracker]

bitchen crank and 350 or 283 mains, havnt seen any benifit from 400 mains. but maybe my stuff isnt making enough steam to need them :smt102

Paul