455 block with 430 heads

[Mr.Green]

My 430 block has a cylinder problem. The block is 40 over already. If fix the cylinder the 430 would become 60 over. I was told it would be thin an over heat..is the true? I have an option to fix the 430 block..or purchase a 455 block an do it 30 over which will make it 461. With the 430 heads and stage 1 valves which block shall I use? Mr.green

[Dr. Frankenbuick]

My 430 block has a cylinder problem. The block is 40 over already. If fix the cylinder the 430 would become 60 over. I was told it would be thin an over heat..is the true? I have an option to fix the 430 block..or purchase a 455 block an do it 30 over which will make it 461. With the 430 heads and stage 1 valves which block shall I use? Mr.green

You may be able to go .020" more on your bores, but it depends on core shift. Sonic testing is the best way to determine how far you can bore. A sleeve in the bad cylinder could save your current rotating assembly if there is just a problem with one cylinder wall. It would be cheaper then balancing a new rotating assembly and buying new pistons and rings for an overbore.

The stage one valves will have more shrouding in a 430 block. I would use a 455 to have the least shrouding with stage one valves. The early 400/430 heads were prone to cracking. I would want to have them tested for cracks before spending on a stage one valve conversion.

[Mr.Green]

You may be able to go .020" more on your bores, but it depends on core shift. Sonic testing is the best way to determine how far you can bore. A sleeve in the bad cylinder could save your current rotating assembly if there is just a problem with one cylinder wall. It would be cheaper then balancing a new rotating assembly and buying new pistons and rings for an overbore.

The stage one valves will have more shrouding in a 430 block. I would use a 455 to have the least shrouding with stage one valves. The early 400/430 heads were prone to cracking. I would want to have them tested for cracks before spending on a stage one valve conversion.

the machine shop has both motors the 430 heads has been worked on now with the stage 1 valves the 455 block will be machined an I have to buy new pistons. Which pistons flat or stock dish? If you can email me at king_green@ymail.com I can let the guys at the shop read your list of tips on how to do buicks..455 bottom block with 430 heads..thanks