Technical update. On-line information says the Michigan casting after March 2,1977 is OK.
This is a Michigan casting, March 25,1977 and it is cracked, NOT OK.

 

Thanks Tim!

I noticed that the Midnight Modified block does not have the large ridge next to the distributor, is that indicative of a certain casting facility? My current build also lacks that ridge, but I have seen many 351M/400 blocks that have it.

Also is there a date when the Michigan Casting Center (MCC) blocks began displaying a cracking issue? Ending later than we thought it looks. Can they be effectively sonic checked to determine suitability for rebuilding?

Thanks again!

 

Sad to see the crack issue widen on date cast.

Tim, I know I have never seen any info on other casting locations. I know my engine was, well the truck was delivered to the dealership in November of 76. Began life as a 351M, and it carries the CF casting(Cleveland Foundry I would believe). Never came back with cracking issues from the machine shop.

Curtis

 

Thanks for the update Tim.

 

As for the ridge on the block. As I understand it all factory 351m and 400 have a high ridge, 351c ha a low ridge. I has to do with the deck height.

 

when I built my 400 the first block cracked after being baked. if I remember right it was about a month after the so-called good date.

 

This doesn't make me feel very good about the block I just got done breaking down, 7C16...I know this thread is a little old, but has this been found to be as big an issue as pre 7C01 blocks?

 

Well i have a 400 73 Michigan block that has withstand 2 rebuilds and one with aluminum heads, your pistons and a mild roller cam, and still rolling....

In my opinion the weak blocks could be all blocks that don't have the reinforced lifter valley....

 

That's a lot of blocks