Some shots of the casting flaw (porosity) found last week. Since it's right at the joint of a main web we're afraid of a crack. the circled part is a crevice about 1/8" at it's worst, 1/16" for most of it....
Has that been mag'd yet? That doesn't even look like a "crack", although it could turn into one! That looks more like sand/casting flaw! I say unless you KNOW its a crack, lightly grind/polish that area, THEN magnaflux again! If its a crack, sorry!!
Clint Have you checked to see if it can be welded? I know that cast iron welding is possible and usually done successfully if not in a severely stressed area. I saw a set of heads that had one of the chambers welded. Wasn't a problem and it was a high compression motor. I've also seen lots of blocks welded where the motor mount broke off in a wreck. It's worth checking into.
Clint, What kind of a build is planned for the block? That mild impression can be grooved and hot welded. I don't believe you would have any problem with that block unless your planning a 650+ hp engine that you'll be doing 3500 rpm launches with every weekend. Fixing that should be less than $50 US. Good Luck.
Thanks guys, I didn't think that cast iron could be welded successfully, I will look into it this week though. If I use the 74 block, the shop is going to eat the machining costs and I only have to live with a delay, so I get a 76 block already bored & line honed free. Maybe it's a good way to go... The buildup tagret is 480-500hp 530tq street/strip use. I get to the track about 3 times a month, about 7000 cruising miles per year. Here's the details as it stands now... 71 Stg 1 heads, unshouded, backcut, port matched, polished, flowed (Cam will be selected once flow numbers are in) JE pistons, 38 over, 691 gram, full float Balanced & bluprinted rotating assembly Rod polished, peened, ARP bolts, 10 under Billet double roller SP1 Intake full length headers Head stud, main stud, pan stud kit, oiling mods 4000 stall SP converter
Clint, If you would, take another pic of the flaw about three feet away and arrow the location. I just want to get a better idea of the area in question. I've had blocks repaired that had actual cracks and they held up well for quite awhile before I blew them up. But none of the failures had anything to do with the repairs. With the build you are planning, you shouldn't have a problem.
