A 283 built from an "870" block????

[Jim L.]

This is a stretch and I know it. In fact I'm more than a little skeptical, but here goes:

I got a call from a friend who is working on his '64. The engine and all its internals are at a machine shop for freshening. The machinist has informed my friend that the engine block, a righteous 870 casting dated August '63 has cylinders that measure 3.935" and a crank with a 3.00" stroke.

In other words, this 870 block is a .060 over 283, NOT a 327. And it hasn't been sleeved to get the bore to be less than 4". Neither is there enough cylinder wall thickness to bore it another .060 to get it to be a 327.

Now no one is claiming this is the original engine for this '64. That's not the point of this.

The real question here is has anyone else ever heard of a 283 based on an 870 block? If so, what is the back story?

Thanks in advance,
Jim

[Joe L.]

Re: A 283 built from an "870" block????

This is a stretch and I know it. In fact I'm more than a little skeptical, but here goes:

I got a call from a friend who is working on his '64. The engine and all its internals are at a machine shop for freshening. The machinist has informed my friend that the engine block, a righteous 870 casting dated August '63 has cylinders that measure 3.935" and a crank with a 3.00" stroke.

In other words, this 870 block is a .060 over 283, NOT a 327. And it hasn't been sleeved to get the bore to be less than 4". Neither is there enough cylinder wall thickness to bore it another .060 to get it to be a 327.

Now no one is claiming this is the original engine for this '64. That's not the point of this.

The real question here is has anyone else ever heard of a 283 based on an 870 block? If so, what is the back story?

Thanks in advance,
Jim

Jim-------


This situation makes no sense, at all, to me. First of all, I have NEVER heard of a 283 based upon a GM casting #3782870 block.

Second, in the world of GM castings, virtually all block casting numbers are SPECIFIC to a certain FINISHED bore size. I know of no exceptions to this, at all. So, even if the block did have an original finished bore size of less than 4.00", it should be able to be easily bored to 4.00" (and, greater). I'm not saying that GM would have bored a block casting that was intended for a finished bore size of 4.00" to a lesser bore size, but IF they did, the block should still be able to accept a 4.00" (and, greater) bore. In this case, you're saying it will not.

If the block will not easily accept a 4" bore size, then I say it's NOT a GM #3782870 block even if that's what it says on the bellhousing flange. If it does say 3782870 on the bellhousing flange, then it must have been some sort of foundry mistake in which pattern elements of an '870' block with that number on it were used in conjunction with pattern elements for a 283 block of some other and unknown casting number. This would create a mis-identified '870' block. I don't even know if this sort of thing is possible, let alone whether this sort of foundry mistake would ever have made it to a finished engine, but it's the only explanation I can think of for the situation you describe.

[Jim L.]

Re: A 283 built from an "870" block????

Joe, thanks for your insight. I don't know what to believe about the block because I haven't personally inspected it.... yet. What I (think I) know is only what I was told.

When I can inspect it, I'll make and post pictures.

Jim

[William C.]

Re: A 283 built from an "870" block????

I'm with Joe, any chance it was Sleeved for a racing application in it's past? Years ago, some of the NHRA Stock class boys dis some unusual things to strengthen the the cylinder walls, and NHRA checked bore and stroke, not block castings (heads and intakes yes, but not blocks in the late 60's early 70's)

[Clem Z.]

Re: A 283 built from an "870" block????

check the bell housing number closely as that is the easy one to change by milling a pocket in the number area and shrink fit in the number cut from another block

[William C.]

Re: A 283 built from an "870" block????

Good Point Duke, does the block have the (870) number cast into the front face of the block behind the timing cover-in the timing chain area

[Mike M.]

Re: A 283 built from an "870" block????

check the bell housing number closely as that is the easy one to change by milling a pocket in the number area and shrink fit in the number cut from another block

i know of a sbc that started life as a 870 cast # 327 ci, then some scondrel removed the 870 cast #, welded in
a 548cast #, and removed the motor mount bosses from each side of the pseudo-548. sure runs good as a "283" , which after bore and stroke displaces 364 ci. mikie

[Clem Z.]

Re: A 283 built from an "870" block????

i know of a sbc that started life as a 870 cast # 327 ci, then some scondrel removed the 870 cast #, welded in
a 548cast #, and removed the motor mount bosses from each side of the pseudo-548. sure runs good as a "283" , which after bore and stroke displaces 364 ci. mikie

shame on you mike.

[Dick W.]

Re: A 283 built from an "870" block????

Clem, it was people like Mikie that put the old man Norris Friel and Bill Gazaway in an early grave

[Jim L.]

Re: A 283 built from an "870" block????

I'm with Joe, any chance it was Sleeved for a racing application in it's past?

I asked about sleeves, but was told no. Sleeves are pretty obvious so I accept this at face value.

The most viable explanation I've so far read is that there was an "810" 283 block. That suggests either someone confused the "1" for a "7" or the "1" has been altered to resemble a "7".

Stay tuned. Film(?) at 11.....

Jim

[Wayne L.]

Re: A 283 built from an "870" block????

I've seen several late 519 blocks that were cast with both "519" and "870" inside the timing chain area and at the rear verticle face which gets covered up by the flywheel and bellhousing. FWIW, Wayne

[Jim L.]

Re: A 283 built from an "870" block????

I've seen several late 519 blocks that were cast with both "519" and "870" inside the timing chain area and at the rear verticle face which gets covered up by the flywheel and bellhousing. FWIW, Wayne

That's fascinating and I didn't know that.

That's not the case with this block, however. It has turned out to be a total fraud (big surprise, eh?).

Newest news: This block was originally a 3849852 283 block. Some grinding and some JB Weld had turned it into an "870" block.

The mind boggles at how disappointed an owner would have been at the performance. Imagine expecting the torque of a 327 and getting the revs of a 283 instead.

Thanks for all the comments and opinions.

Jim

[Clem Z.]

Re: A 283 built from an "870" block????

That's fascinating and I didn't know that.

That's not the case with this block, however. It has turned out to be a total fraud (big surprise, eh?).

Newest news: This block was originally a 3849852 283 block. Some grinding and some JB Weld had turned it into an "870" block.

The mind boggles at how disappointed an owner would have been at the performance. Imagine expecting the torque of a 327 and getting the revs of a 283 instead.

Thanks for all the comments and opinions.

Jim

at least they used JB weld there was one was faked using RTV that blew off in the quarter car wash. i posted many years ago on this board take a screw driver with you and poke at the casting numbers. JB weld and iron filings have been used since the 80s that i know of. the bell housing milling number insert trick was used to fool race track tech inspecters for years before the advent of P&G cubic inch checkers.

[John H.]

Re: A 283 built from an "870" block????

I've seen several late 519 blocks that were cast with both "519" and "870" inside the timing chain area and at the rear verticle face which gets covered up by the flywheel and bellhousing. FWIW, Wayne

Wayne -

That's not uncommon - many of the front and rear bulkhead pattern elements were shared across several different casting number blocks.

[Jim L.]

Re: A 283 built from an "870" block????

at least they used JB weld there was one was faked using RTV that blew off in the quarter car wash.

At Cypress Gardens one year, there was an airbox '57 with an engine casting date made from modeling clay. The owner was careful to not let the engine get warm enough for the clay to loosen and slide off.

Jim