Is there a more sought after 440?

[Sixt8Chrgr]

Is there a structural difference between the casting numbers 4006630 and 2536430. I may rebuild a 440 and put in my Charger and the did not know if one of the blocks was superior to the other.

Thanks

[HDCharger]

I have heard the "Thin Wall" casting is a myth.  No matter which one you choose it will have to be magafluxed, sonic checked, etc. to make sure it is good.  Dave

[b5blue]

Really you should have both checked out first one may just be in better shape generally. I don't think thinwall is a myth, it states in the MoPar B/RB book that they "should not be overbored more than .020" for racing". It goes on to say that a thinwall overbored to .020-.030 may be better because of the larger water jacket for a street car.

[YGBSM]

Thinwall is a myth, been proven over and over again.  E-berg and 440source have both done research on this and sonic-checked many supposed thinwall blocks. 

Also, later blocks (I think '69 and up) have a stiffening rib on the side and and some point the mounting ears got beefed up too.

[firefighter3931]

Sonic checking the block is the best way to determine the best re-build candidate. Some of the earlier castings have been known to be thin while many later 76-78 castings have thick walls. You can get good and bad with both...


Ron

[Sixt8Chrgr]

Which casting number could possibly be the thin wall block?

[375instroke]

Read the source: http://www.440source.com/blockinfo.htm

[TexasStroker]

You are fine with any 440 block...just have the basic tests performed anyway to be certain.

I have recently heard that the MP books might have advised folks to avoid the later blocks not because they were thinner (they were not) but rather they stated that as a way to suggest guys go with earlier castings because there was better quality control etc...