I have a friend that took his 1977 440 block to a mopar machine shop this week to have it built for his mud truck. the shop owner told him to take it back home because it wouldn't work. he said the max you can bore any of the newer blocks is .020. He said the same thing with 400 blocks. So he talked him into buying an older 440 block he had. I have ran several 400 blocks that were .030 over with stroker cranks and have yet to have a problem. Has anyone had a failure on a block because of too much overbore on a newer block or was he just trying to get more money?

They always use to say that, but I have had newer blocks sonic test better than an older bock, I would say that you are safer with the older block, but either way the best 60 bucks is to have it tested. Then you have no doubt in your mind as to what you can do safe.

I remember reading here a while back where someone sonic checked a bunch of blocks and the later model blocks were no different than the earlier ones. Any of them can be thin, best bet is to have it checked. The myth that the later model blocks are too thin is just that...a myth.

i have never spent any time confirming this idea but a friend of mine that owns a machine shop told me that by looking at the cam bore bosses you can get an idea of how much core shift the block has. i don't know how reliable this method is but it's certainly worth mentioning.

look at the cam bore bosses at both ends of the block if the bored hole is noticeably offset in relation to the boss then the block has a lot of core shift. of course having the block UTd is the best idea especially if larger overbores are desired.

I have 2 440 blocks, one '66 & one '77, both are in cars & .030 over with about .220 minimum cylinder wall thickness left. Both had a fair amount of core shift, otherwise they'd have about .260 left IIRC.
Sonic testing is something I consider mandatory for any performance build before money is spent on pistons & machining. Also, for building HP, I prefer thicker walls over getting the next .010, .030, or whatever bigger bore.

You all can say what you want BUT i had two 400 later year blocks crack right down the middle of cylinder ,two differnt motors and different cylinders .that was with a 0.030 over bore .Spend the money and get it sonic checked , you might get lucky .

Unfortunately, you may or may not be spending money you didnt need to on another block. I have sonic checked over 400 blocks, and there is one thing that is consistent. There IS NOTHING consistent! ( the GM blocks are more consistent than the Mopars for sure) The ole MP rule of only .020 overbore is garbage. I am surprised any shop anymore doesnt sonic check a block,subcribes to that theory, and randomly has a customer assume a block is junk. Thats the shops job, to check and provide information resulting from proper procedure.Sounds like he ha d ablock he wanted to get rid of????

As far as the " good" or " bad" blocks, there is no such thing. The nickel content can be different, some blocks can be harder than others etc, but the only way to know if its good is to sonic test, magnaflux and or presssure test. I recently checked one of the vaunted " 230" blocks, standard bore. Customer paid ( i think) $300 for it bare. It didnt sonic test very good. Will need a couple sleeves to do it right. You just never know.

As far as core shift, yes, sometimes that rule stands true as to bore centerlines, cam tunnles, oil galleries etc. the problem is when you have a centered core, but how do you know if there is a thin spot or void in the casting on a cylinder. You will often find blocks that sonic well, then all of a sudden there are voids or bad spots, sometimes 1" round or bigger in a bore test. I actually cut an old block open once to confirm after deaming it junk. Sure enough, a very thin casting, along with rust, had thinned that area.

I think the shop could have done you better with a test first, but if he's your guy, then you have to roll with him. Good luck with your build..

I took a late model block to renowned racer FJ Smith to be sonic checked. He told me I was wasting my time and money "those blocks are all too thin". I told him it was a myth and do it anyway. Guess what ... he's been converted!!

I had 3 blocks sonic check this week . 70-71-78 71 was the best 70 could be used and the 78 is junk. you don't know what you got till you check them. had a friend have 5 blocks checked. only 2 of them was any good. all you can do is do all the test check and look at then hard !! all these was RB blocks.

I have a 78 440 overbore 0.055 It make 700 hp aprox.
4 years in this tune. You dont want thin walls but I dont think you need the big thinkness that some say you need.
Some said the same about Al blocks they move around to much you lose to much HP. If you build one on kill you might need that thickness otherwise its not a issue.
Jim
ps I would give the shop a little break on this He might be trying to do the right thing by you and not screwing He might not be a idiot just has a different opinion.

http://www.440source.com/blockinfo.htm
 
Check out the link above, very interesting. I know my uncle has a newer one bored out to .060 on a stroker.

Thanks
Scott

My '76 block is bored .055 over for a 526" stroker. I used the late model block because of the extra meat around the mains.

Well I was going to start a new post about the blocks. I had tested but I think the Info would be good here. I got some pics and sonic test numbers. I stated that the 78 was junk not really true now that I have the numbers in my hand. so here are the numbers if you click on the pics they should get bigger so you can read them. block 1 is a 70. block 2 is a 73 and block 3 is a 78. and when I got home I found other 71 block. I will take up to check.







.Now there is some talk about looking at the meat around the cam in the front. this might hold true by a wee little bit.









this last pic is the worst one I got for that and it is a block that been bore .030 over race in my car for years, was in a super gas car before that

I wanted to add that the 78 block does have more meat around the mains....and I am tired of move these heavy a$$ block around !!!!

aluminum block wow that be nice....might be little over kill for a 550hp motor lol.. So the old age question.. how thin can you be on the thrush and non-thrush side of the cy's ?