Thread: 671 on a SBC

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well the boost is were you can get in trouble if you do not run much boost you would be ok but there is alot to tune one in so with cast pistons and a hi cr you can have a melt down . should look at a way to pull timing out when it starts to make boost like the msd btm box i run this on my 548 it is 10to1 and makes 10 inch of boost works fine

I found a new Holley 420 Megablower on ebay for a great price, worth keeping an eye on.
Keep in mind a 10:1 motor @6 lbs boost results in an effective compression of 14:1!
A mid 70s motor may just be in the right range compression wise, 8 1/2:1 or so. But cast pistons and crank + 2 bolt mains won't take a lot of boost abuse as mentioned above.