Ok, I have a 71 511 virgin 4 bolt block, and plan to build it to about 500hp, All I hear is how much better the 509 2 bolt is (thicker webbing and stuff). Is it really that much better?
Will the 511 be good for 500hp?
I plan on studs for the mains, I know that doesn't help the webbing being thinner. But it should help a little.
It is going to be a hot street/strip motor, so it will not see continuos abuse.

Does the 350 4 bolt suffer from the same webbing problem as the 400 4 bolt?

I guess I just want some re-assurance Lol.

At 'just' 500hp in a BBC, you shouldn't have a problem. From what I have read, a 2-bolt with good bolts can handle well north of the 500 mark, so you should be fine.

Chris

For a street engine you should be OK.. Lots of racers have run the 4-bolt 400 SBC..Usually its a rod bolt or something else that will let go first anyway.. The 350 4 bolt block doesnt have the same problem with the outer cap bolts intersecting the webbing/bottom of the cylinder bore.

For 8 years my son ran his '66 Chevelle at Westhampton Dragstrip with a 2 B.M. 406" SB. Included studded mains, internally balanced (H.M. job), cast crank, #993 "Canadian" smog heads, fully ported with 2.020's, 1.600's, (Mitchell hadn't released the Dart heads just yet), 5.700" rods, TRW (pressed-pin) Flat-tops, a Weiand intake, 780 Holley, a 230 @ .050" X .480" hyd. cam, a 12 bolt (Geis-girdled) 4:10 rear, and a set of 10" slicks. Had a "cheater" system installed. Car ran consistent 12.20's on "muscle", 11.20's on "juice". Weighed in at 3600# with him in the driver's seat. Left the line with the left front wheel "in the air" (on the bottle). We used stock Fel-Pro's #8364PT's which went back to them for analysis, they were interested how they
"looked" after all the "abuse". Never lost a gasket or anything else. The only thing my son did was throw a set of rods and mains in after about a 4 year span, never touched the rings in all the years. Never broke one partCar was constantly in the winner’s circle. Thanks, Gary in N.Y.
P.S. I still have the time slips here.