are the 3970010 casting #'s good foundations to build up on?

 

Depends. The research I found on those numbers show it was mostly cast as a 327 block. The 350 block, for that number comes back as a 2 or 4 bolt main. So if its a 350 - 4 bolt main - yes solid engine, provided it has no cracks and the bearings still fit, its an old engine. The other ones are fine too. Have it checked at a shop for stability and such.

 

I have three 350 blocks all are the 010 casting they are a good block made in both the two bolt and 4 bolt versions the only real way to know is to look. Dont be afraid of the two bolt block for a normal street engine they are fine commonly rated to handle 400 hp more with studs. The two bolt block can also be splayed making it stonger than the conventional 4 bolt, but in general the 4 bolt is more desirable. Once you really start looking into castings you will find info regarding other casting numbers on the block 010 and 020 these are found under the timing cover they are supposed to designate a high nickel (010) and high tin (020) block some use this as a selling point the validity of the markings is somewhat questionable especially after the early 70s (according to my machinist) two of the blocks I have are 010 the other is 010 and 020 visually the casting looks better on the 010 020 block so who knows!! When I check out a block I look to see if the camshaft bose is somewhat centered and also the lifter gallery also some blocks I have seen have air pockets in the casting I am running one like that now in a cheap buildup I would not invest alot in a block like that. Once you find one that looks ok take it to the shop have it pressure tested and or magnefluxed and cleaned and alignments checked. If I didnt have one ready to go for a winter project I would also look at gm goodwrench I think you can get a new 4 bolt main block for $600 adding up the cast for purchase cleaning checking finding out you have a bad block and redoing the process makes the $600 appealing I assume they might already be bored to.

 

Thanks for the info guys. My block has 010 on the side of the block,above the oil pan.I haven't got to pull the pan to see if its a 2 or 4bolt yet. I was trying to read the # on the front of the passenger side head the other day, to get alittle more so i can find out if its a 2 or 4 bolt, but it was kinda hard to read.

 

Here is a pic of mine I built up, it has the casting number 3970010 and is a 4 bolt main 350. Puts out about 350hp and 400 lb ft of torque.