I have a early 630 casting 400 block im considering using for my next build. It is a 12/71 casting date. I am just curious if this block checks out ok what are its limitations with just some main studs and aftermarket caps?
Ive heard they are stronger but how much more can they take? Should I go ahead and make this thing a 512 stroker with those Victor heads? Most articles that mention horsepower limitatations are vague.

only way to tell for sure is get it sonic tested. even the good stuff has a bad day.

You're right. The #s are 3614230 which is right but the mains are thicker for several inches. Looks like still a good candidate if it checks out ok. Its only gonna be a pump gas engine but I'm hoping I can stroke it to 500+ and put some good breathing heads on and have a good reliable engine for years.

My first pump gas low deck stroker (before stroker kits where availble) consisited of a 1972 400 block that sonic tested okay, it ended up with four ductile iron sleeves due to rust pits and a bad deck surface due to a blown head gasket It was the only 400 block I could find at that time and I was stubborn I bought and used a set of the Mopar brand ductile iron main caps, ARP main studs,a Ohio Crankshaft Company 4.25 stroke crankshaft, CAT brand 6.800 long H beam rods and a set of 22CC dish Ross custom pistons that ended up making 9.25 to 1 compression with a set of ported 906 heads that had 84.0 CC combustion chambers. I used a low deck Eddy six pak intake and vacume carbs set up by C&J Engr. in Whittier, CA The motor made 612 HP at 5600 RPM and 644 FT lbs at 4500 RPM on California pump swill back in early 2004 My message is most low deck 512 make good power and torque I have since switched a bunch of parts out of the motor, Eddy CNC ported heads, a 4.300 stroke crank to make the motor have zero deck to up the compression to 10.29 to 1.Tthat combination with the same cam and six pak intake and carbs made 718 HP at 5800 RPM and 745 FT lbs torwue on OR pump gas three years ago in Madras, OR I put a set of CNC ported 440-1 heads and a 400-3 intake with a 1050 Dominator on it earlier last year, that combination made 775 HP at 7000 RPM and 728 ft. lbs at 4800 RPM on Oregon pump gas at Klamath, OR (4300 ft. above sea level It now has a set of Indy SR MW size intakes and a 400-2 intake with a Holley 850 double pumper carb,I'm hoping to run that combination in my car at the MATS race in Las Vegas next month I would look at replacing the stock caps with either steel or aluminum, your choice Don't waste your money on the four bolt type Buy a set of main studs, if you don't get them with the caps

Living dangerously Cab? lol.

Good news! Hope it works out fine, Let me know if you need help.

Read this http://www.440source.com/blockinfo.htm . AR Engineering http://www.arengineering.com/index.html did an article for Mopar Action that also dispelled the thin wall myth but I can't seem to locate it, and the link to it in the 440Source article no worky.

Kevin