Rockn-Roll

I have finally cleaned up the block...it's completely naked except for freeze plugs and oil plugs which I am going to keep in there since they are too tight and might break if I force them. I was wondering if anyone could tell me what some of these numbers mean.

Here's the front of the block:


Here's the rear (click on image to see a detail image):


These numbers are at the top rear of the block:




Now, when I turn the engine over there's some numbers that actually read upside down:

Number over oil filter (click on image to see a detail image):


Numbers under fuel pump (click on image to see a detail image):


Finally, here's some of the reason why I'm getting better horsepower than the stock 165BHP as the dyno says 203RWHP with the only visible parts exchange being a manual tranny and side exhaust:

Letters indicating measured cylinder diameters near each cylinder (I don't know what the number means, but my pistons all have a stamp with the letter for where they belong, 1 F, 1 G, 5 H's, and 1 J) (click on image to see a detail image):


Now, this final image is scary...very scary. It shows what appears to be a deep gouge on the milled head-2-block mounting surface which runs next to a bolt hole and into a cylinder (click on image to see a detail image):


No, it's not something that I damaged when taking it apart...here's what that section of the gasket facing the block looks like (click on image to see a detail image):


Both the block and gasket are indentions as if some tiny projectile flew in between the block and gasket and cut it's way through. Here's the other side of the gasket:
(click on image to see a detail image):


As you see there is no cut on the other side of the gasket...it's smooth. So, that would indicate the damage was not due to something like a screwdriver or something stupid like that lying in between the gasket and block when the engine was put together cause if that was so then the gasket would show signs of the deformation on the other side of the gasket.

It's like a twilight zone episode. The engine was running great except for an oil leak at the rear main seal and oil leakage past the valve stem seals which caused a little smoke at startup. The cut is larger at the outside edge of the block and gets smaller toward the cylinder, which would indicate that either something went into the cylinder from the outside and decreased in size like wore itself down...but what?!?!? Or, something was ejected from the cylinder and expanded when it left...but I just can't imagine fuel and oxygen ripping apart steel like that. Plus, the line is so crammed straight! What possibly did this?

It doesn't look like any blown gasket that I've seen before cause usually it's just the gasket that gets blown away, not the steel block getting ripped open. Any thoughts?

Rockn-Roll

Help. Trinity. A little help!

Rockn-Roll

I'm taking the block to a local machine shop to see what they think about the gouge...several phone conversations indicate that it's a blown head gasket.

77BuffaloVet

awesome detail...wish I could tell you what the numbers mean. I hope that someone will soon!!!

Jeff's Classics

3970010 is the casting number, pretty common block used on Corvettes and even trucks, some 2-bolt some 4-bolt.
The other patterns near the casting number were used to indicate the date the block was cast. Off the top of my head I can't tell you how to decode it, you may be able to figure out by looking at it and seeing if there are 12 numbers or letters (month) and another 31 or so for the day.
the 010 and 020 numbers indicate that this was a high performance high nickel content block. This is good.
Don't know about the rest of it. The gouge is probably from human error during assembly or transport of the bare block, just a guess.
Jeff

Mike Ward

What's on the stamp pad at the front of the r/h cylinder bank?

Rockn-Roll

The numbers there match my VIN number ...already figured that out.