id inline 6 block

[jim372]

i have a gm inline 6 motor that they value cover is marked 160 hp
but i think block is auto block.
fot one it has steel freeze plugs
the casting nos. are 3994257
gm under that then
88 under that
also has c121
can anyone tell me about what i got

 

[Fishermark]

Re: id inline 6 block

Only real important thing to consider - other than the actual condition of the block - is whether or not it has the extra mounting tabs on the block for the front mount. It can be seen here on the left side of the the timing gear:

If it doesn't have that, you will need to fashion something to mount the front mount to. Here's what I did with a block that did not have it:

 

[jim372]

Re: id inline 6 block

it came out of a late 60's boat
mount is there i just was worried
it would not stand up to marine us

 

[RogersJetboat454]

Re: id inline 6 block

i have a gm inline 6 motor that they value cover is marked 160 hp
but i think block is auto block.
fot one it has steel freeze plugs
the casting nos. are 3994257
gm under that then
88 under that
also has c121
can anyone tell me about what i got

From what I can find 3994257 is most likely a 250CI I6. If you measure your lifter covers, and they are around 5" that will confirm it is most likely a 250. If the covers are taller then it is a 292.

C121 = March 12 1971 (or '81) it was the date that the block was cast.

I believe there is a pad somewhere around the distributor that has a suffix code stamped into the block when that engine met its final destination from the engine factory. The suffix code may be able to be decoded to tell you what the engine was installed in, and in what factory.

 

[HT32BSX115]

Re: id inline 6 block

it came out of a late 60's boat
mount is there i just was worried
it would not stand up to marine us

There's no difference between the "marine" block and the automotive block......other than brass core plugs (AKA inaccurately as "freeze-plugs") and engine mount-points in the front.....

The 230/250/292 series engines were probably some of the best marine engines ever made.....