I was wondering about ribed 360/390 blocks, I have 2 so far and my understanding is they started around 1971, i also have a 74 ribbed block, most of my later blocks are d3te,d4te mirror 105 blocks. The ribbed blocks do not seem to have any special features or extra main webbing.

anyone have late 75 or 76 ribbed blocks?

 

The ribbing was done to theoretically add some strength to the side of the block, and is not tied to the appearance of the upgraded main webbing on the 105's, which were cast at a different foundry than the earlier blocks.

 

Matt seems to me I have seen both 73 and 74 360/390 blocks with the either ribbed sides or the 105 block with the extra CJ webbing at the crank saddle.. meaning the 105's were out there before 76 or 77.. I had to quit looking after 5 years + here in VA...Its all Chevy or Mopar country..and all the FE's are all in the melter.... Here I moved back to Gods country 20 years ago...and didnt realize this place in VA SUCKS when looking for FE parts...But when Redmanbob (Bobby) was looking for C4AE-G heads I told him just were to go and he scored..Some 15 years after I had left SoCal....But right now I'am happy with my little 68 429CJ I had to have my nephew pick up for me in San Diego..LOL...

 

Another theory I've read is that some of the tooling for FE blocks was starting to wear out and that's why some blocks got the ribs.

 

I dont know why there is still this much confusion on these blocks after all these years but cyclone 416 is correct.The ribs showed up in 1968 as a result of some of the molds becoming weak after the millions of them that had been cast to that point.Fords engineers came up with the idea to machine grooves into the molds to give them some support as they were starting to collapse by then.The idea worked great and they kept right on using them.You see these blocks advertised all the time as a service 428 or reinforced 428 etc just to make them sound like big bucks but the grooves give little if any extra support plus ford never had any problems with the sides of those blocks.The FE block has always been very stout regardless.

 

I've heard the same thing.

 

i was wondering why my block had the ribs

 

----------------