Is the block junk?

[bb71challenger]

I have a 340 that had a cracked block from dropping it as far as I can tell. The crack was at the tranny mounting flange and ran into one of the dowel holes. I was broke at the time and put the engine together anyway after getting the block welded via torch and high nickel rod. The engine was all new but had chrome rings and either I did not give the engine time or the rings failed to seat so I parked my car in disgust. I am wanting to use the engine but dont really know how to go about it. machine it and put the dowel back in would probably be a must. Getting rid of the chrome rings would probably be another and maybe getting the rotating assembly balanced. It has some good stuff like comp cam steel roller rockers and forged pistons. Is the block worth messing with or should I look for another block or maybe use as much of the goodies as I can for a 360 build? Thanks for your input.

[moper]

You may have distorted the block with the welding. Prob not, but it depends on the crack and the fix. Welding is always done before any machining. You must have the dowels int he right spots to keep the trans lined up. Wall finish makes or breaks the ring seating and sealing. Chrome rings take a long time to seat. Like a few thousand miles. If this is a weekend car, you have to drive it to seat them. I would pull it apart, have the bores near the welding chekced. If they are bad, remachine it all and start from scratch with modern machining and parts.

[matt63]

I doubt you would have hurt the bores from the welding but it should be checked.  If they are good I would re-hone and re-ring.  It might be possible to bolt the bellhousing or tranny to the block and redrill/ream a new dowel hole.  If you get a new block the cost to redeck, align hone, cam bearings, washing, boring/honing, plugs, etc. will be much higher than the above.

[Moparal]

I believe chrome rings take a very fine mirror finish to seat well, and the gaps need to be right on.

[bb71challenger]

I believe chrome rings take a very fine mirror finish to seat well, and the gaps need to be right on.

I know for a fact that the gaps are not right on. Being my first engine and filing them by hand I got a couple of them at the far edge of spec. The hone did not look mirror finish either, it was ordinary crosshatch. I also heard that if the bores were not perfecty round the rings would never seat either. Thanks guys for chiming in, I know now that the block, while needing some attention, is still worth keeping. I have tossed the idea around that since I am not cloning a 71 Challenger but putting it back stock except for the R/T hood I should put a small block back in it. I have a 70 project that I will make a R/T clone out of and I know I cannot put the 340 in there because there was no such monster.