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Just a little history question

6K views 12 replies 8 participants last post by  400smb_s10 
#1 ·
I just picked up a motor out of a 5 ton truck and I was wondering what anyone could tell me about it. Id number is 3951511. i havent checked the head numbers yet but I wanted to know if anyone knew anything about it the guy said it was a 350 4 bolt main. any help with be appreciated

thanks in advance
 
#4 ·
no idea i just baught it from a guy tonight that got it from a 5 ton truck. It has all the plates and motor mounts on it like it came out of somthing heavy duty like a school bus or bigger truck etc.

3951511....400...70-73...4...Some replacement blocks had 2-bolt main caps
so does this mean this is a replacement block?
 
#5 ·
ok i have similar history.
I got a c 50 chevy truck that have a 350 in.check on the air filter assy. that is a good fondation for a hot rod motor .those truck have a forged crankshaft and ''x'' rods inthere.those motors are made for rough work, so they got the good stuff.
good luck!

Michel.
 
#7 ·
400smb_s10 said:
what happens if it didnt come with an air breather assy.. ?
Look at the front passenger side of the block where the head and block meet. There will be a pad there that may have numbers and letters stamped into it.

Look for a string of numbers that ends in letters- that will be the "suffix code". The suffix along w/the date code from the back ledge of the block (near where the casting number is located, possibly on the other side from it) can in many cases be linked to a particular vehicle.

The date code will look something like "D221" and will be raised up (cast) into the block as opposed to stamped into the block like the suffix code.

Suffix codes were repeated through the years in some cases, that's why you usually need the date code to narrow it down.

The SBC 400 never got a forged steel crank from the factory. There will be basically no difference in the short block of a 400 from a big truck or from a station wagon or Caprice. The heads may have bigger (3/8" instead of 11/32") exhaust valve stems.
 
#9 ·
400smb_s10 said:
ok did some looking this morning and the number i found was on the back of the block not the front and its (CONV1) thats the only other number i found hope that helps
Nah, that's a foundry ID- no help.

Maybe this will help. The photo below is seen as if you are standing in front of and just to the passenger side of the engine. The suffix code is seen on the unpainted flat area in the foreground:



Casting numbers- http://outintheshop.com/faq/casting/castings2.html
Suffix codes- http://chevymania.com/partsid/suffix.cfm?block=Small


The date code and casting number of an earlier block is shown below (later blocks have "5.7L GAS" adjacent to the date and/or casting code):



The date code can be on either side of the back of the block. Its formatted w/letters for the month followed by the day of the month, then a single digit for the year. So, "D 25 8" is April 25 of a year ending in "8". The suffix and the block casting number together will allow the exact year to be determined.
 
#10 ·
I'm no expert on 400s, for sure. But, I thought that 400 SBCs had a different number of freeze plugs on the side of the block than any of the other pre-LS SBCs. Is that correct? It wouldn't confirm exactly what the motor is, but if the seller told him it was a 350 . . . .

Pat
 
#12 ·
PatM said:
I'm no expert on 400s, for sure. But, I thought that 400 SBCs had a different number of freeze plugs on the side of the block than any of the other pre-LS SBCs. Is that correct? It wouldn't confirm exactly what the motor is, but if the seller told him it was a 350 . . . .

Pat
Some 400's had 3 freeze plugs on each side instead of 2 like the rest of the small blocks. But not all, some had 2 freeze plugs. The 400 I had only had 2 freeze plugs each side, it was a 2 bolt main. I don't know if there's any significance to that or not, it's just what I had, 2 bolt main with 2 freeze plugs per side.

Ed
 
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