HI PAUL MOST ANY MACHINE SHOP SHOULD BE ABLE TO PLUG THE CRACKS BETWEEN THE VLVS ,,WHAT THEY DO IS DRILL A SMALL HOLE ALL THE WAY THRU THe crack IN THIS CASE IT LOOK LIKE A 1/8 INCH WOULD DO IT , THEN THE HOLES IS TAPPED AND A PLUG IS SCREWED IN ,IT IS ACTUALLY A TAPERED THREAD , AND THEN THE PLUG IS BROKEN OF FLUSH, THE NEXT STEP IS TO DRILL ANOTHER HOLEUSING HALF OF THE PLUG JUST INSTALLED AND SO ON ALL THE WAY ACROSS THE CRACK, WHEN IT IS DONE IT ACTUALLY LOOKS LIKE IT HAS BEEN STITCHED AND IT WON,T EVER LEAK, DOESN,T TAKE AS LONG AS IT SOUNDS , AS THE TOOLS ARE MADE ESP FOR THIS AND IT CAN SAVE A VEYR EXP HEAD OR BLOCK, MOST ANYTHING MADE OF CAST IRON CAN BE DONE THIS WAY . JERRY