Maximum bore BBchevy
 

I would like to know the max. bore for a tall truck block.And if anyone knows a machine shop near Baltimore. I want to go 4.530.Thanks in advance JIM :?:

Maximum bore
 

427 truck block is good to 4.350" to 4.375" maybe. I would fill it to water pump holes for that big. But you can use a 4.375" stroke or possibly 4.500" stroke on tall deck to get maximum cubes, depending on rod length. This would take cubes from 505 to 540 range.

It has to be a siamesed bore block to go above this size which is a Bowtie GM block or Dart, etc.

Remember, a tall deck block and aftermarket heads create issues with headers fitting in any stock frame car.

That being said, a tall deck or short deck 496 is just a small bore 540 and will do a very good imitation of one if the combo is correct.

I tried that a few years ago on two blocks and there was not enough metal it bores through and we had to sleeve the block and go smaller stock blocks from what i have seen want go 4.500

Re: Maximum bore BBchevy
 

The largest bore I've seen in a stock block is 4.390 (.140 over). A friend of mine has it and it also has been hard blocked too.

TS1955

Many production blocks have thin cylinder walls, even at standard bore.

I would go easy on the intended power level, (and in doing so... the cylinder pressure), If I was forced to overbore a stock block drastically.

For a 4.500" bore, it's time for a Dart or World block.

You are correct.

TS1955

Dart only !!!!

I wouldn't try the 4.5 stroke either, as you'll likely hit the oil gallery in the oil pan rail while trying to clearance it............Not sure if they made the truck blocks in the priority main style oiling system though......that would allow it to be opened up a bit..........

X2 on the Dart block :!:

Dart or world block only for the 4.500 bore

I agree that a dart block is the way to go. I used a 502 gm block with a 4.25 stroke and 4.530 bore to make a 548. It was 868hp and the block help up fine.

I'm working on a Dart Big M now with a cracked oil galley. It's leaking oil into the coolant passage.

TS1955

x 2
JMO - Max reccomended on truck block is 4.25 with steel rods at 2.10 journal (SBC size).