[unruhjonny]

At what point does this particular casting become a concern towards reliability?

I have one in running shape that I am going to be striping the top end off this weekend, and since it's in good running shape, I was thinking of swapping it into my car;
I was thinking of maybe using it as my Pure Stock motor depending on how the bores look, and the pistons it has already installed.
(My PSMCD thread)

Any opinion that could be shared is appreciated.

[NBF823]

I don't know that the '77 got the XX cast block, which just basically a '74 is block. I think some '77s had the 557 block.

Best to list the cast number here I'd think.

[unruhjonny]

I believe that the '77 W72 block was the heftier casting - and this one is a 4spd block to boot.
I actually don't have the engine in my possession till this weekend when I get it back.

[jm455ho]

Need to check casting number, as I also believe the XX blocks were only used in 78-79 T/A 6.6 cars.

['ol Pinion head]

Have owned two '77 Y81 project cars, and currently own a '77 Y82 project car. Each had it's original WA coded engine, all had 500557 casting blocks....not a later XX 481988 casting block.

On a PSMCD build for a '70 Formula, one would think Jon, that you could find an earlier (70-75) 400 block that could at least bolt in to a '70 chassis. Once one gets to these later 400 blocks, whether the thin web "557"s, or the late XX 481988's, it's going to take swapping to '75 motor mount stands on the subframe, or contrapting with adapters to get one to bolt up in an early subframe.

[starlightblack]

JON, I'd be real interested in that engine as I have a '77 4-speed W72 car with no W72 400....

I have a running 1975 YS 400 , 500557, casting date C31 5 - as OPH described - to trade?

[unruhjonny]

@ Starlight: I'd happily humor anyone looking to buy this engine, but the shipping cost to you would be very prohibitive.
In addition to my date & numbers correct engine for my car, I do have a 1972(?) 400 shortblock - so I have no need to trade.

@oph: when I bought the engine, I freshened it up, and put it in a 1973 Firebird, I see no reason why I might have issues putting it in my car - and from a performance standpoint, this later block offers zero edge over an earlier block;
I have heard of block mount boss differences between early and later blocks, but I have personally never dealt with any castings newer than this one - but admitedly, it has been many years since I installed this one, so if I had to do anything to make it work, I have long since forgotten.
I'm a younger guy (in the grand scheme of this hobby), so saving a couple bucks by not having to machine/build another shortblock is a real perk for me.
I was just wondering if at stock-ish power levels (I'm not going to be going as far as to require anything more than pump gas), if this casting might be a cause for concern.

If my memory serves me correct, the 1977-L78 block was a lighter casting than the 1977-W72 block.

I really appreciate the input guys! - keep it coming

[starlightblack]

Canadian Freightways - $300 to Ontario (my '77 is in Ontario). Just shipped one out of Kelowna for a buddy of mine. Think of a price - I'm interested.

[unruhjonny]

ok - you can email me through my profile, I'll think about it.

[JD311]

The 2nd gen firebirds use the later style mounting holes on the block (2, close to oil pan rail one above it), 70-81. They changed the mount design in 75 to the clamshell lower and steel upper. Had an "XX" block here and it looks just like the 74, and 73 we had here. You could have even drilled and tapped for the earlier mount holes for 1st gen and GTOs, etc. The bosses were there.

[unruhjonny]

whoops!

Long since sold!