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Is it really a 400 small block?

TruckNutzDude

TruckNutzDude

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I just picked up a "400 c.i." small block from a local shop and I want to make sure it is what I paid for. I was told it was from a '70 Chevelle. How can I tell for sure what it is and what it came from? I got some of the casting numbers off the back of the block, they are, 330817. There are 2 freeze plugs on one side and 3 on the other IIRC (need to double check that but the engine is not in front of me right now.) Are there any other distinguishable marks on the 400 engines? I took the pan off and the heads will be off later this week but it looks like I did get the wiseco pistons he said were in there :grin:. The rockers are stock stamped style and the timing chain is a double roller, the cam is supposed to be a mild RV style and the springs are supposed to be good up to .510" lift.

I'm also looking for some suggestions as to how I should build this thing. I'm either dumping it in my '83 S-10 or into my K5... not sure quite yet on how it would like the K5's TBI setup.:o
 
the front damper (balancer) will have a chunk machined out of it because it is externally balanced. Go to moretec.com (I think that is it) and run whatever numbers you find on it. The flywheel will also have a weight on it, again, externally balanced.
 
re read, if you have the heads off, bigger than a 4" bore, 4.125" I think, but I can't remember for sure. Easy way when it is complete is the balancer, though.
3.75" stroke (center of rod journal to center of main journalx2
 
On the back of the block there is a lip where the tranny bolts to.. On the drivers side of that lip there should be a string of numbers. That will tell you what the block is out of or intended for... I have a book at home that shows what the code for the different blocks. I imagine there is somewhere on-line that lists them also.
 
he beat me to it.

we are brothers in blocks buddy, i have the same casting numbers. welcome to the club. 2 bolt mains.... way to be
 
TruckNutzDude said:
I just picked up a "400 c.i." small block from a local shop and I want to make sure it is what I paid for. I was told it was from a '70 Chevelle. How can I tell for sure what it is and what it came from? I got some of the casting numbers off the back of the block, they are, 330817. There are 2 freeze plugs on one side and 3 on the other IIRC (need to double check that but the engine is not in front of me right now.) Are there any other distinguishable marks on the 400 engines? I took the pan off and the heads will be off later this week but it looks like I did get the wiseco pistons he said were in there :grin:. The rockers are stock stamped style and the timing chain is a double roller, the cam is supposed to be a mild RV style and the springs are supposed to be good up to .510" lift.

I'm also looking for some suggestions as to how I should build this thing. I'm either dumping it in my '83 S-10 or into my K5... not sure quite yet on how it would like the K5's TBI setup.:o
Click to expand...

The 400sb never made it into a 70 chevelle.
 
TorkDSR said:
he beat me to it.

we are brothers in blocks buddy, i have the same casting numbers. welcome to the club. 2 bolt mains.... way to be
Click to expand...

Head casting date: F 13 73 (June 13 1973?)

8998897 (not really legible) guessing it really reads,
3998997 which would be a 73-75 350/400 head with 76cc chambers

You guys have been extremely helpfull so far. Ringmaster, thanks for the link!
 
tyco91burban said:
The easist way to tell is by looking at the freze plugs 400s have 3 freeze plug bosses but only two drilled out on one side of the engine
Click to expand...

This is not always true, I've seen SB400's with only 2 freeze plugs per side.
 
Muddytazz said:
This is not always true, I've seen SB400's with only 2 freeze plugs per side.
Click to expand...

That is correct. If the block has 3 freeze plug bosses, then it is a 400. But, not all 400's have the 3 bosses.:deal: :waytogo:
 
SB 400's have recess in balancer as mentioned earlier, but also rounded protrusions (bumps) along both side of block unlike all other smallblocks which are flat.
 
You are pulling the heads, just look for the steam holes in the heads and block.


Before pulling it apart, do a compression check, and or leak down test. Does it really need rebuilt?????
 
SUBFAN said:
You are pulling the heads, just look for the steam holes in the heads and block.


Before pulling it apart, do a compression check, and or leak down test. Does it really need rebuilt?????
Click to expand...

Can I do a compression test without the engine being in a vehicle? I've never done one but I have access to a compression tester. I don't know if it needs a rebuild but it was sitting the corner of a custom car shop uncovered with no valve covers or oil pan for about a year. It's very dusty inside but there is no rust on the cylinder walls or anywhere else as it was covered with oil before sitting in storage. Maybe I could get away with a good cleaning and a new oil pump? The engine ran when it was pulled, the previous owner traded it off for other parts/ money he owed. I trust the guy who gave it to me so it SHOULD be a good running engine as it sits.
 
Why not??

Sure you can to a compression test out of the vehicle!--all you need is a starter and a battery,and a way to jump the solenoid to make it crank--just take all the plugs out,and make sure the motor is supported good so it wont flop over on you while your cranking it,and screw in your tester,and crank away!--its best to do a compression test when the engine is warm,but not critical--my theory is if it has good compression stone cold,it will likely get even better as it warms up and the pistons and other parts expand...if it has good compression,maybe you can get away with a good "douching" and run it as is...:crazy:
 
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