i know that you can make a 360 into a 390 by just changing the crank and some other easy stuff since there the same block but i heard that you can do the same thing and get a 428 from a 390. is this true. or do you just get a 410 or something.

 

From what I understand, most 390 blocks can't be bored out enough to get you to 428. 410 with the longer stroke crank is reasonable though. There are a lot of threads and a few arguments on this, if you use the search function. I'm sure someone will hop on here and tell you how wrong I am. haha

 

Russ your not wrong at all. It really boils down to the block your using and what cyl wall water jacket cores it was cast with. Most 360 and 390 blocks were cast with different wall cores than the 428 blocks were cast with. But there are some cases where the block in question was cast with thicker wall cores. You need to sonic map the block for thickness and coreshift. Done right this will show the true potential of the block as each one is slightly different. You can gap the cyl wall cores with drill bits to see what cyl cores the block was cast with. This will give you some idea going in what you've got. But the sonic map will confirm this and show any flaws. I'm a firm believer in boring the least amount needed to clean things up. Not just going for the max overbore the block can take. This leaves you room for future overbores if and when it's needed. You can make a 410+ from a 360-390 by using a 428 crank with 390 rods. There are 410 pistons made with the correct pin height for the longer stroke. There are also the Scat stroker cranks and kits to up the cubes. Also ups the price. So it really depends on the build level details how involved one wants to get.

 

well your going to find People out ther that have taken 390 blocks out .080" and swear by them.....I think anyone who gets down too a .100" cylinder wall and then strokes it ! Is outta of Freakin minds!! JMO... some may get by with it for a Race build where the motor only see's a 11 sec blast..but as a daily driver...going miles on end and heat build up! No thanks!

If ya want to a 428.....Just back off to a safe bore that will last..and stay cool on the street.... 10 cubes would be just for bragging rights and not much of a seat in the pants rush !! JMO

~Russ

 

I would find a D3 or a D4 Block if it was me. Also make sure there is .100 left of the cylinder wall, as a very min!!! But its not for everyone. There are blocks out there that you can to it with, like G has said. When we did the Poor Mans 427 (D4 block) we hit water @ 4.25 bore size. So you will need to check the spacing between the bores and sonic checked.
JMHO

 

thanks for the info. my block is a D3. i don't think that i am going to bore my block out at all since it only has 4,530 miles on it since it was balanced and blueprinted. i just wondered if it could be done cause i heard from a couple of guys that it was easy. now i see it is easy but could lead to problems that arent worth it. i did know about the 428 crank and rods cause my dad did that in one of his trucks. thanks for the info!!

 

Many 390 blocks can be bored to 4.13 (428 bore), just have it sonic tested before you have it bored. I like .150 minimum on the thrust side. I have two 428 blocks that are now bored to 4.170 and still have over .150 left.

Think about it, if I had bored them to the stock bore of a 427 which is 4.23 it could be done, but the walls would be so thin, they would collapse with normal use. So the point is, just because you can bore it to a specific bore, you might not want to unless you have enough wall thickness to work with.
That being said, many 390 blocks can be safely bored to 4.13