DragStuff

Is it a good idea try to go427 or434 with stock block I have a fully machined bare block has anyone had problems with durability when stroking a stock block is the after market block mandatory ?

You will get a wide range of answers. Personally, if I already had the block I would run it until it gave problems. I have a production block with a 428 rotating assembly in mine, with no issues so far...

my concern is will the clearancing neccessary compromise the strength of the block you see if theblock gives me aproblem its prolly gonna damage my rotating assemblyIm just concerned if its a bad idea to have stroker built out of factory block from what I understand 2boltfactory 400 block stronger than 4bolt400 block doIneed aftermarket block to step up ?

here is something to think about when stroking a 400. if your not running a rasied cam you will have cam clearence problems which means you won't have any good cam choices because of the base circle and your lobes will be hitting the rods with a good base circle. i am building a 406 with a bowtie aftermarket block for a friend and after doing lots of cam research we decided against stoking it and decided to bore the cam journals to 50mm so we can go with a better cam profile this will really help increase the power band we are expecting around 850 to 900 hp
this is a 14.1 18 degree motor tho. the last motor combo dyno 842 at 8000rpms but it was 16.1 400 then. so do your home work before thinking cubic inches is all you need.