Technical Pulled this crank out of a 283, but casting # doesn't compute!

This crank came out of my 283 that I bought, I ran the only viable numbers on the crank but can't find a reference of it anywhere. The casting number is supposed to be near the front of the engine, but this one is near the back. The other numbers appear to be the casting date, and the letter "N". Wierd.

 

It's got too many digits. If you take just the last seven digits (3876768) it equates to a 1964-67 283 forged crank, small journal, 3" stroke.

 

3876768, 283 Forged, Small 3.00". I'm not positive but I think the 25 is on the crank after the GM. The only thing I see is that it seems to look like a cast parting line but I can't really tell from the picture.

Pat

 

Info here that backs up what they said. http://www.chevytech.com/2c50o9.html
Or here http://www.chevytech.com/2c50o9.html

 

That's not a forged crank.

 

GM25 is some kind of internal foundry use number.

 

The crank flange is 1965-1967 283/327 and here are the balance of the markings:

 

K 29 6 makes it a 1967 model year crank. (Nov 29th 1966 casting date)

 

Well, that is in keeping with the block casting which ID the block as 1964-1967.

 

there should be a casting date back there, too.

 

Take a picture of the parting line on the journal, if it's sharp and a clear straight line it's a cast crank. If it's about 3/8" to 1/2" it's a forged crank. I had many 67 283 engines and cranks they were all cast.

Pat

 

All 283 cranks I have seen are steel, the one pictured is cast.
The rear flywheel flange is round on a 283. The one pictured has a notch on each side, this appears to be a 327

 

I noticed that also, i'm considering using a 327 crank also. up a 283 to 307 cubes..... maybe measure the stroke.

 

since not many guys have seen a cast 283 crank, maybe they have a notched flange? The steel cranks are round, but this isn't a steel crank.

 

I've never seen piston skirts like that. All of them are like that.

 

For Squirrel, appears to be late-66 block.

 

Sure looks like a cast crank to me.

If the last several digits are 3876768, this place suggests it is a cast 283 crank.
http://www.nastyz28.com/sbcmenu.php

 

I was unaware there was ever a 283 cast crank, were they a small journal like the steel ones?

 

I've only heard rumors of forged 283 cranks. I've owned at least 5 cast units, all 64-67 blocks. Currently have 3 in my possession.

Devin

 

The source I looked at online said it should forged according to the number. But I agree, that parting line looks cast.

 

I've noticed that occasionally, there are errors in online sources. There are also errors in books. Looking at stuff, and measuring it, usually finds the facts.

 

Bore on the block is 3.875, so I guess it is a 283 cast crank instead of a 327. I was hoping...

 

Our engines, may have been made the same day, id like to see the date on yours.

 

I think it says: J66, which I guess means October 06, 1966.

 

327's (and 307's) have a balance weight/pad on the crank flange, just like 350's do, only it's smaller than the 350's, so they are not "round". You already know that you have a cast crank, but from what I've been told, they were nodular iron; see the "N" on the crank? As far as the pistons go, they have steel struts on the inside of the pistons supporting the pin bosses; I've never cared for that, and "good" aftermarket cast pistons do not have steel struts, but some of the cheaper ones do. Hypereutectic and forged pistons do not have struts either. I had a 283 short block not long ago that had a cast crank too; at that time, I too thought all 283 cranks were forged. I even asked the question here on the HAMB about it. I gave that entire rotating ***embly away to a fellow HAMBER, as I had a forged 283 crank, aftermarket rods, and forged pistons going back in. I have't gotten around to ***embling it yet; too many other things going on it seems. I've seen many 265/283 cranks that have a completely round flange, but there are just as many 283 cranks with a notch in them, forged or cast (???). The 302 cranks, small and large journal, also have the notch. Are the pistons oversize? Looking at your parts, I see the rods are the 2nd design 327 rods, with the extra metal "shoulders" around the rod bolt heads. I wonder why/how that is, unless it's been rebuilt some time in the past. 265, 283, early 327 rods are pretty light weight around the rod bolts, don't have the shoulders, and are completely "round" at the sides where they ride against each other. The 265 rods are especially lighter weight. Used to be a racers weight saving trick to use 265 rods; less weight, faster revs. So, your crank is fine, the rods are better than 283 rods, the pistons leave something to be desired, but will be fine for a stock ring and bearing type rebuild. If the block needs to be bored, I'd get "better" pistons. That's JMO. I am Butch/56sedandelivery.

 

It looks just like a cast 283 crank.I have a cast one with the same number on the counterweight in an engine in the garage right now. Not to worry,I have done BAD things to cast crank 283s (and 301s)with no crank problems

 

Like I have said before the 66-67 283 cranks were cast. Early ones were forged. I have the parts to build the oft hated 307 with a 67 283 block and forged 327 crank, we were going to try a fuel economy motor
John Gunn and I using early 305 heads but he p***ed away before we could finish it. What are you looking to do with that motor? A rebuild on it and a mild hydraulic cam and you would have a sweet running engine.

Pat

 

I plan to overbore .030 to get 287 cid, Comp Cams L79 clone cam, 305 heads that are 601s that I have, an Edelbrock C3B or an Offy with the oil tube I have stashed somewhere, Edelbrock or Holley 600 cfm carb - whichever runs best. It is going to be mated to the Powerglide it came with. My '58 Biscayne has 3:55 pegleg rear for now, its what I got to work with.

 

Take a nice forged box end wrench and drop it on a concrete floor. Notice that the sound it makes is almost like a bell ringing. Now stand your crank up on end on the same floor, pick up the wrench and use it to give the crank a quick, sharp rap on the counter-weight someplace where there's no machined surface. If it makes a nice ringing sound like a bell, it's forged. If it's more of a dull, short "clank" sound it's cast.