What is a 25500179 block?

[TTA850]

I know it's a stage 2 but what exactly is it?On center or off center?Can it be used in a turbo buick application?I've looked over on GNTType with no mention of this casting muber.

Thanks in advance,
Steve

[KendallF]

I don't see it anywhere in the books I have...which doesn't mean much as I have a S2 on-center with a weird part number also. The fastest way to find out if it's on or off-center is to stick a set of heads and production intake on it and see if they line up. Also look at the oiling setup and caps. Generally speaking, cast caps mean off-center Stage 1; steel caps mean S2; wet sump is an off-center or early on-center. 6 bolt caps and/or dry sump means it's a later on-center S2.

[TTA850]

Thanks Kendall,so I guess it's not too weird to find a stage 2 with an unknown number on it.Best I can tell it's a 3.8L on-center stage 2 block.How far can the bore of a 3.8L stage 2 go?Can it go to 4" safetly?

Thanks again,
Steve

[Ted A.]

No, unless it's one of the siamese bore 3.8's.

[750H.P.V6]

TTA850,

The casting # you mentioned is for a short deck Indy block. Is this the block for sale over on Ebay? If so it belongs to a guy here local, actually he has 2. They are completely useless unless you are building an Indy motor. You could have a nice flower box.

Neal

BTW, The siameese bore 3.8 blocks have the same casting # as the regular 3.8 blocks (25500012).

[TTA850]

Neal,
Thanks for the info - this motor is local to me and I wanted to find out why it is for sale for much less than most stage 2's,especially considering it looks like brand new.

Oh well - the search continues

[750H.P.V6]

TTA850,

Sorry for the bad news. I'm just glad you didn't get stuck with that block only to find out you couldn't use it after the fact.

Neal

[mygrain]

Why are indy motors useless?

[750H.P.V6]

Mygrain,

Not all Indy motors are useless. It depends on the vintage. The early Indy motors used Off center blocks which will work for our application. Indy Light motors have a lot of good stuff in them that we can use and are 274" to boot.

The short deck Indy blocks are very unique. To the best of my knowledge they used 2.66" strokes and thus the deck was very short. Just looking at one I would say the difference is greater than .500".

The lifter bores in the block were re-located for the square port heads they ran and require special cams, lifters etc. The blocks are dry sump too which isn't a huge deal. They are completely incompatible with anything on a GN.

Check out the one over on Ebay and you'll see what I mean about the lifter bores etc. Weird stuff.

Neal

Hey Neal, How are you doing?
Since the subject was brought up about the 3.8 siamese blocks what whould you, (or maybe Bill Anderson if he reads this)consider to be the Minimum "safe" cylinder wall thickness for 800hp or so? just wondering how far these blocks can safely be bored out to!
BTW the repair on my dads block is looking good the guy whos doing it is a FAA certified welder w/t 30+ years Experience! He guaranteed it would be good as new once he was finished!

[Ted A.]

If it is a siamese 3.8 basically, its just a 4.1 block that wasn't punched out more than 3.800. I thought I saw .180 somewhere for the minumum wall thickness.

Anybody sure on the # for minimum wall thickness? I would like to have it for my future records thanks, since I have one of these blocks.

[750H.P.V6]

Gene,

What has been stated above is basically true but you can go with a minimum wall thickness as little as .150" if you're only shooting for 800 H.P. Keep in mind there have been a couple of guys that have run motors with 4.065" to 4.070" bores which will have a wall thickness less than I stated but they weren't at an 800 H.P. level either.

On your motor and your Dads too I think the factor that will limit the overbore size are the cooling holes drilled in the common wall between the cylinders. I pondered this myself and I figure you can go 3.860" without any cause for concern. After that a sonic check in that area should be your guide.

Hope this helps
Neal

P.S. Don't have your Dads block fixed before we get some $$ out of Fed Ex for the damage, pain and suffering etc.

[indyrich07]

hey you guys! Where the heck is that block on e-bay,Whats it under. I wanted to take a looksee at it. Thanks.....Rich

[flynbrian]

Hey IndyRich,
The guy is just a short drive away from you, here is the link: Short Deck Indy Block!