jason y - that's good information. I'll take a look at my block.

MOP - Awesome site!! I'll check that out and match up what I have.

BillK - My crank is a 2 piece... and it's in 2 pieces. lol That caused tremendous heat and cracked the block at the journal. Probably the same problem with your block that has a crank in 3 pieces.

Man... I always know where to get advice when i need it. Thanks everyone!!!

If you have 2 bolt mains, when you machine the block put in studs for the mains and you will be fine unless you intend to spin it 6k rpms.

GM did not have seperate castings for auto/truck/marine.

Since you are only using the block and need to buy a crank, I would stroke the engine. I have built several 496's and you will not be disappointed. Call Bob Mandra for a cam and heads. Its not that more expensive and truely priceless.

Good luck!

I am not sure what took this one out The cam was broken in three pieces as was the crank. It was out of a Scarab that a friend of mine bought knowing that the engine was junk. The engine has been worked on before so who knows what happened. All I have to say is that it must have been one heck of a sound when it let loose

Mine, the crank was in two pieces. But before I wrote it off, i fired it up one last time to be sure it was still knocking... and it started and ran, but it didn't sound good. Unreal!

Just thought I would revive this old thread. I wanted to post an update. With the information I had at hand, I decided to basically run the 87 GMC 1 ton single wheel truck engine like it was sitting. It had 85,000 miles on it. I pulled the oil pan and noticed a cast crank and 2 bolt main. I changed the oil pump and oil pan. Left the bottom end completely intact. Put on my roller cam/lifters, Dart Pro 1 heads and dropped it in my boat. I am now nearing the end of my second season with it, and it still runs great. Granted, I'm a little weary to run it too hard for too long, it's still holding together (knock on wood). Now I'm debating on weather or not to pull the engine, and stroke it. It's clearly underpowered to my starboard engine.

Cast crank is fine till 500+ hp and 5300+ rpm

Yeah, i'm only running about 4800 RPM and I would guess I'm well under 500 HP. But now i want to stroke it.
I would use H-Beams, dome pistons, forged crank and studs on the mains. I would use the same top end, roller cam/lifters/rockers, Dart Pro 1 heads. Should be good to 5500 RPM.
Anyone want to take a guess as to how much HP that would produce?

What's cam specs? Can will determine everything... Hard to get more then 550 hp without rpm on that CI.... Under 5500 its nearly impossible ... Unless you do some very good research in parts and use custom can for YOUR PARTS

Well, let's say I stroke it... 4.280 bore, 4.250 stroke = 489 c.i.d.
Cam is Crane Roller Retrofit --> .553/.556 lift, duration @.050 214/222
Heads are Dart Pro 1 --> 310 cc runners, 121 cc chamber
Pistons are dome -17 cc = compression ratio of about 9.5:1

Exhaust... can't remember brand, but aluminum manifolds with separate chambers only 12" long --> I wonder what a pair of long tube headers would do for me...hmmm.... probably not worth the cost of upgrade, plus probably would be difficult to fit with my "S" pipes.

Send pic of exhaust..440-476-4114

That's a SMALL cam especially for any kind of hp... Mine are 547ci... Aluminum heads... Cams are .578 lift 232/240 duration on a 114 built very conservative made 597 hp @5200 and 670 tq. @4100... I bought them this way done already... When I redo I'm going custom cam and bigger carb and looking for 700hp not hard to make 600 up on 547ci...