502 overbore, how far can it go?
 

i have ta chance to trade some parts for a bare genV 502 block with main caps. the block is bored at .060 over and the guys machine shop says it just needs to be honed to be ready to go. i have read conflicting info online, some people say you can take a bbc to .100 or even .125 overbore and that the 502s had siamesed walls so they can take it even more. but then i read other places taht say .060 over is risky? my goal with the motor is to get into the 600-650hp range n/a with a stroker crank, after market heads and custom cam. all forged internals, H beam rods.... all the goodies to keep her strong and dependable. nothing too insane, no plans for boost at all. or am i better off snagging a 454 block and doing a 496 with it? thanks in advance for any advice

i wouldn't use a 502 bored more than .030'' ,but that's just me

if i am reading that right that says you can only go 30 over but i am finding pistons and rings all over that for 60 over. here is one for example

http://www.ebay.com/itm/PISTON-RINGS...item20b7c65886

sure way to find out is to look at gm parts catalog...if they dont sell them,its because they know better...i work in harleys,and they dont go over .030'' in evolution engines...jobbers sell the +.040'',but i wouldn't use them,as the cylinders get too thin and distort under heat....but then again,jmo...

I don't know about a Gen V block but I did see someone that has taken a Gen VI to 4.560 to make a 555 stroker. That was pushed to the limit for a GM block.

Here are the typical stroker bores, typically 540 is where most marine engines stop with a GM block, anything after that is usually aftermarket. Also, these are all typical for 9.8 standard deck blocks, if you get a tall deck aftermarket block you wouldn't even be thinking about these low numbers.

4.470" Bore Size is Standard 502 (actually about 4.466) depending on hone job.

4.500" Bore Size to Make 540 cu in ..OR in 4.530" Bore Size to Make 548 cu in..OR in 4.560 Bore Size to Make 555 cu in .. OR 4.600 Bore Size to make 565 cu in

A lot of guys do .060 over, I have been looking for a bare 502 block they are getting hard to come by. How much will you have in the block or in your case about how much are the parts you are trading worth. Be sure you have a machine shop check it out first.

Your really .030 past whats reccommended already. I wouldn't build a 502 production block out to 4.560 as you are getting the cylinders walls pretty thing and you will either get cylinder distorion under a load or worse. The reason you see 4.560 and bigger pistons is the aftermarket blocks like the merlins and darts can use the same bores and strokes and can be bored further safely, Smitty

More than one of the engine builders that are advertisers here on OSO, have personally told me that going .090 to .100 is perfectly safe even on a blown motor.

we have bored the gm gen5-6 blocks to 4.530 have not had any problems,i would be a little nervous going to 4.560 would be a good idea to have the block sonic tested