0.040 bore? An RB 440 block at 499 cubes used to be 4.375 bore ( 0.055) x 4.15 stroke by 6.760 rods for a normal 500 build.
440source kit is like this in a 40 over bore Useing a 4.15 crank and 6.76 rods 84 cc eddy heads ar the closed chambered type. I see dish on yours. Are the heads open chamber? is that a 1009 felpro head gasket @ .039 thick? Your pistons almost look like they need knurling now.
4.360"
(.040 over) -4
(Flat-top) 1.867" -.018" 13.15 12.21 11.85 11.51 10.90 10.71 10.52 440.500.5094 10.90 com with a flat top and 84 cc
I have a 4.375 bore block ready to assemble. I used to race it in my cuda, but went with a mega siameese block. This block made me 885 hp and I was afraid of breaking it. It has been decked, prof honed and clearanced for bme aluminum rods. Not sure if I would sell it tho. I can find you a block if you needed one, or even any member could. I do know the block I have is ready to assemble and has no issues. It is a plateau hone as well as my mega block is. I believe it is a 69 model block
What year block is yours Per? After a certain yr, the #3 main with the thrust bearing was bigger/thicker. If it was a newer block and old style bearing, then the crankshaft would have excessive travel and could cause the havok you are experiencing now.
Don's 496 I just built was a 72 block , so it has the old style main cap thrust face to. Around 75 was the change I think. It would take close to 3500/4,000 dollars to build and prep a block from scratch to handle up to 700 hp useing your heads and cam and stay together. For instance ... Dons block had almost 1k done in just billet mains, girdle, bore, cam bearings, honing, bottom hole taps, and hot tanking up to 4 times through each process. Don bought the billet mains and the girdle. My block is square decked and trimmed, so the 440 source kit at .018 in the hole is less. Then by the time you add the kit, the assembly labor , it stacks up on the cost. I usually have to have the balance done myself, even if it comes balanced already. Then the crankshafts in most all kits has to have machine work done to be right. Even the small end on the rods usually has a pin fit problem of being a little tight.
Sorry about your delema. I just now read your post. If there is a way for me to help you out , drop me a line.. We (cc.c members) can atleast find you a good block that will take a 40 over bore if you use the same pistons. They look like they need to be mic'ed and re checked to me. You may experience a little piston rattle since the knurl is worn off the side of the pistons. Hard to tell by your pictures.
This is the 512 kit I was thinking of doing something like this for my spare block
4.375
(.055 over) -4
(Flat-top) 1.485" -.010" 13.82 12.81 12.42 12.06 11.40 11.12 11.00 440.512.5073 4.375x4.25 x 7.100 rod length
