68hemi

See title

MelWff

small journal, 1967 302, 327, 350

68hemi

That same casting # was used for all three engines above or are you just saying all of those engines are small journal?

MrTrim

Small journal 327. I've also never seen a small journal 350, they were all large journal as far as I know. I think only 68/69 327's and 307's were large journal. Also I'm not sure about 302's. I'm sure someone smarter than me will chime in here about the 302's.
Chris

cardo0

Just don't order/buy parts before you pull the oil pan.

68hemi

It is a bare block

MelWff

Same casting number used for all 3 in 1967 and are all small journal. Google the casting number.

GearheadJoe

The '657 block was used mostly for small-journal 302 and 327 engines. However, this same casting was also used for Chevy's very first 350, used in the 350 RS Camaro. Chevy simply machined the same bare casting for large journals.

So, the 657 casting itself can be found in both small journal and large journal versions, but the large journal version is somewhat rare.

One way to visually recognize the difference, even without using calipers, is to look at the bearing tangs in the main journals. The small journal versions had BOTH the small journal tangs and the large-journal tangs (see attached photo from John Hinckley). A large journal version has only the large-journal tangs, since the small journal tangs were cut away when the journals were machined for the larger size.

So, any 657 block can be simply line bored for large journal mains if desired. I did this for a 383 that I built, just to take advantage of the stronger crank.

ILBMF

302's are 327 blocks essentially

68hemi

That is true but for a numbers guy that is restoring one of the few 1967 Z28s that has to be a hard block to find.

GearheadJoe

I'm not sure I agree that such a block would be hard to find. See my Post#8 above.

There were hundreds of thousands of '657 blocks installed in Camaros and passenger cars. GM simply machined the same raw casting for either a small-journal crank (302 and 327) or a large-journal crank (350).

If your restoration project is a 1967 Z28 302, that engine had the more common small-journal crank, so you don't even have to worry about large journals.

One thing to note is that both the Tonawanda and Flint engine plants made the '657 casting, and there are subtle visual differences between the two castings that experts can recognize.

I *think* that most or all Camaro '657 engines came from the Flint plant. In that case, there are only four "numbers" that matter if the '657 is a Flint casting:

1) Casting number
2) Casting date
3) Engine assembly stamping on the pad
4) VIN derivative stamping on the pad (if this was used for the Z28)

So, if you don't have, or you wish to duplicate, the original 302 that came in the car, the best you can do is to start with any '657 Flint block from any Chevy (Camaro, passenger car, etc.), and make sure that the casting date is suitable for the date that the car was built.

It is technically possible to re-surface the pad and stamp different numbers on it, but that topic is controversial and I won't go into it here. However, the only block in the world that has the original numbers is the one that the car was built with. Aside from that block, all Flint '657 blocks with an acceptable casting date are essentially equal with regard to the "numbers."

I don't know how Camaros are judged, but in NCRS flight judging, most of the points assigned to the block are tied up in the casting number and the casting date. The engine assembly number and the VIN derivative stampings on the pad are worth 50 points (out of 4500 points for the whole car).

That means you can still get a 98.9% score in NCRS judging, even if the numbers stamped on the pad are not correct. A score of at least 94% is required to get a Top Flight.

So, the pad stampings are not a big deal for NCRS judging. They are a much bigger deal to a potential buyer if the car is being represented by a seller as having the "original, numbers-matching engine."

DZAUTO

REGARDLESS OF THE CASTING NUMBER------------THERE WAS NO SMALL JOURNAL 350------------EVER!!!!!!!
The ONLY 350 in 1967 was in the SS350 Camaro----------------AND IT WAS A LARGE JOURNAL BLOCK. Upon inspection, the 67 Camaro 350 APPEARED to be small journal------------------BUT IT WAS NOT!!!!!!!!
The 67 Camaro 350 shared LOTS of features with earlier small blocks (rear hole for crankcase ventilation, vapor separator can inside the lifter valley, cartridge style oil filter, one of a kind rods, etc). Thus, to many people, it LOOKED like a small journal 327---------------IT WAS NOT!
But don't take my word for it, go over to the Camaro forum and ask those guys.

GearheadJoe

Hi Tom:

I think we are in agreement that the small-journal '657 and the large-journal '657 were made from the *exact* same raw casting. GM simply machined the 302 and 327 for small journals, and RS 350 (SS 350?) for large journals.

My guess is that 99% of the '657 blocks out there were machined for small journals and used for 302 and 327 engines. Comparatively few were used for the 350 option in the Camaro.

If the OP is restoring a 1967 Z28 and he wants to make the engine internally identical to a 1967 302, his search for a suitable block will be limited to only 99% of the available '657 blocks. If he somehow manages to find an original RS 350 '657 block that was machined for large journals, he can use that too, and only he and his machinist will know there is a large-journal crank inside.

However, if he finds an original RS 350 '657 block that still has its original pad stampings, he should probably sell it to someone who is restoring an RS 350 and is willing to use the pad as-is.

To the best of my knowledge, all 1967 Z28 engines were 302s, and there is no such thing as a 1967 Z28 350. I believe that the RS 350 Camaro was a separate option that was not a Z28.

I could be wrong about this because I'm not a Camaro expert, so someone please correct me if I'm wrong.

MikeM

Anybody need a "unique for '67 only" Z 28 crank?

ILBMF

The 302 Z/28 motor was considered a ''parts bin special'' and was nicknamed that right from the start. It was developed for the IROC racing circuit and cubes were limited so Chevrolet took a 327 4'' bore block and mated it to a 283 forged crankshaft (3'' stroke). It had GM pink rods, 2.02'' intake valves, TRW pop up pistons and the 30-30 camshaft. One difference between the '69 302 compared to the '67-'68 was the '69 has floating wrist pins.

When I was 17 I scored a '67 Camaro that had a complete '68 302 Z/28 drivetrain in it. Man, was that motor a screamer...top end was unbelievable and it didn't really wake up until around 4000 rpm's. It was considered the highest revving V/8 production engine of the era. I spun bearing in that thing a couple of times and it was the 3rd engine I ever rebuilt. I was very proud to own it.

MikeM

You got a couple of errors there.

The crank had the 283, 3" stroke but it was a different forging and the rods weren't pink. They were shot peened.

DZAUTO

Joe,
You are absolutely correct. As I mentioned in the beginning of my comment "Regardless of casting number--------------------"
Now, with that thought in mind, MOST PROBABLY, GM used the 657 "small journal" block and simply machined it to accept the big journal crank---------------------which was a brand new crank for 67, and unique to the SS(or RS)350 Camaro. NO OTHER 67 model car got a 350 engine, AND, not all 68 cars got a 350, such as the Corvette and Chevelle did not get a 350 until 69. Although, the 68 327s had gone to big journal.
In the past, I have built a couple of 350 engines using a 327 block and having them line bored for the 350 crank (I've also had the mains turned down on a 350 crank to fit a small journal block).

True story.
Even though the 68 blocks no longer had a hole in the rear of the block for a crankcase vent, I once had an early 327 block that still hsd the boss cast into the bell housing flange for the vent hole. No hole there, just the boss. That was the first 327 I built for my 51 Chevy. I didn't know anything about that anomaly back in those days, so I eventually pulled it out of the 51 and replaced it with a 350. Wish I at least had pictures of that part of the block.

MikeM

Early '68 283 engines used leftover '67 blocks and used the complete '67 crankcase ventilation system carryover until the blocks were exhausted. Did not apply to 327 engines though.

ILBMF

If you click on this link https://en.wikipedia.org/wiki/Chevrolet_small-block engine and scroll down a bit to the 302 specs they say shot-peened forged 1038-steel 'pink' connecting rods. They also claim the '67 302 had the same nodular iron crank as the 283, with a forged steel crank that was also produced...whatever that means.

DZAUTO

Prior to 1964, the cranks were forged. In 1964, cast (or nodular iron) cranks were produced and installed in the lower perf engines.
This is a prime example of misinformation which is sometimes published, and the people who are not knowledgeable or familiar with what was and what was not, take this kind of information and accept it as gospel.
Probably what was MEANT, was that the 1967 302 Z28 engines had the same stroke as a 283------------which they did, 3in. But all Z28 engines (both 302 and later 350) had FORGED cranks---------------including the 67 302.
Personally, I have never come across a cast (or nodular iron) 283 crank. All the 283 cranks that I've touched were forged------------but then that was way back in the 50s and VERY EARLY 60s. Once the 327 was introduced, my kind of folks had no use for a 283, and when the 350 was introduced, we had no use for the 327-------------------and the same for the SB400.
My T-bucket has an FI 327, because that's what was in it when I bought it--------------------but it ain't stayin' in there for long!