Could you use the following formula to extrapolate the possibility that 430/455 blocks shared common water passages? If 430 block is heavier than 455 block by the amount that 45.06 cubic inches of cast iron would weigh. Total bore depth 6.75" substituted for stroke in displacement computation. subtract the lower # (430) from the higher # (455) I would think 45.06 CI of cast iron would show up on a bathroom scale. I don't have any metalurgic knowledge but have seen someone in this group who does. Or, do I have too much time on my hands?
Nah... you just need the Theorem of Sloth. You honestly think an Engineer is going to redesign thier block when they can just slap in bigger bores and head for beer? 45.06 in^3 of cast iron would weigh between 11.08 and 12.70 lbs. However, if the blocks and passages are the same, then it's just the sleeves and you'd need to compare weight differences of just those.
If your asking if the 455 and 430 blocks came of the same mold, and they just punched a bigger hole in the '55.. I wouild say no.. But, of course with the water passages in the same physical spot in both motors, it is possible, but I would have to ask Denny if they actually redid the core box.. I would suspect yes, they did change more than just the cast in "430" to a "455" on the back of the block, but don't know for sure. I do know that 430's have somewhat thicker cylinder walls.. which would be expected since the motors are the same physical size, and share all dimensions beyond the bore size. JW
The casting differences are a fly in the ointment of my theory. But since the cylinders and block are a monolithic casting, Clint, I would think the weighing of 2 commonly stripped blocks would net a difference of the 430 being heavier by close to the amounts stated by you above. And a 400, theorically would weigh that much more again. I noticed your statement, Jim, in another thread about your doubt about the 430 withstanding a .125 punch and it got me to thinking. There's no substitute for the word form the folks who built them. Thanks guys.
I suppose measuring the thickness of the cylinder walls below the water jackets would be another clue. Dont have a 430 here but have a 72 455 tore down.
Tough to make any blanket statements, as blocks do vary quite a bit, but I would tend to agree that for a motor that is not going to have the water jackets filled, then leaving a little cylinder wall in the deal is a good thing. It may have been I was remembering hearing that a 400 could be bored to the 430 specs with no problem.. Have built (and are building) a lot of 455 based motors now, but it has been a while since I fooled with a 400 or 430, to be really up on it. But even taking a 430 to .060.. you want to sonic check it. Fill the water passages, and it's a whole different world.. in a race motor.. 4.360, and 4.375 bores are not that uncommon.. if I recall corectly, Mike's wagon might have a 4.380 bore in it.. Speaking of building motors, lunch is over, I have to get back at it... JW
Great article John, Sort of answered the question that I was trying to avoid. The only error, of impact, that I noticed was his reference to block castings. He said only 76 and late replacement blocks might be used w/o sonic testing, but the 75 block I just installed in my Lesabre had the improved waterjackets, oiling and "455" stamped near starter. Thanks again, a reccomended read and save for anyone.
...one more problem to account for is the relative densities of cast iron. It will vary from 6800-7800 kg/m3. If the 455 blocks iron was even 1% higher in density than the 430's casting you'd find the 455 was heavier. To be accurate and prove your idea correct you'd need to carve out a known amount of cast iron from each block and weigh it. ...not to make things overly complex though...
Sounds like fun. I'm doing my BBChev job this weekend and the guy I am assembling the motor for has a set of calipers I can borrow. Post the size of the insice wall of an end cylinder and I'll see if I can get the caliper to fit. Should be able to get a good enough read to see 1/8" diff.
