[69 chevelle SS]

Hey guys I've got a 350 block in the garage that im thinking of building.....the block casting # is 3970010. Can anyone get any info on this block for me. Is it worth bulding that block up or should i look for a stronger block?. It is a 2 bolt main.

[BoomerADF]

Casting#: 3970010
CID: 302/350
Year: 69-79
HP Rating: 145-370
Application: car & Truck
Mains: 2 & 4-Bolt
Comments: Most common

[Jmark]

According to the shops here in Phx. the 2 bolt '010' blocks are better to build than the 4 bolt. They are a little beefyer than the others. Look at the front of the engine where the timing cover goes and see if you find some numbers like this:

10
20

That will be a "high nickle" block and is very desirable. If you really want a 4 bolt block, just add the splayed caps to a good 2 bolt and you're better off.

[Forsaken502]

I have the same block only in a 4-bolt main. The numbers may also be under the flexplate/flywheel and may look like 010 or 020. As long as you don't run over 500hp they say a 2 bolt main will be fine for street applications. I would tend to agree with them as well. If your rebuilding the engine then have a look at the cylinder walls, make sure theres no pitting, scratches or gouges. Good Luck

[78 monte]

I've had three of these block 2 2bolts and one 4 bolt.All three had 010 under the timing cover.I've still got one of the two bolts was a great motor for 5 yrs still runs too.

[corona jon]

2 bolts are better for the 400's, but i think a 4bolt is better for a 350... when you ghet to the 400 it has something to do with the web casting and the extra holes for the 4 bolt make it weaker.... but on a 350 ive always heard the 4bolt mains are better

[68ss]

I tend to agree with jmark on this one. i have built numerous open wheel modified motors and they prefer the two bolt mains because 1) they are cheap and 2) they are stronger in the web area. you can put splayed caps for even more strength. i have always heard that you look for the block with 010 in the last of the casting for high nickle content. if you need a good web site for casting numbers for bbc and sbc go to moretech. they list everything.

[bracketeer]

2 bolt, 4 bolt, high nickel, mexican, the arguments can last forever. I have built all and have yet to blow up a street motor. If you are concerned with cap strength. Just stud it. Steel cranks are necessary for tranny brakes. Splayed caps for 600 plus HP. Just take the block to a machinist and ask how much will it cost to get it machined for rebuild.