bobb

Well........I found a guy on Ebay selling (2) 455s. I asked him for the codes behind by the distributor hole so I could tell the year and date of casting. He comes back with one that makes sense and one that doesn't. The odd one is a 396021F (with the funky "F", not the stick "F") and the codes of "8" and "322" by the distributor hole.

Now we've recently had the discussion of how to decipher the "8" and "322" in a post I put up a month or so back about Julian date codes. Brian pointed out that the "8" indicates a 1974 block, but what's weird is that from all the info I've seen.....all blocks after 1972 were 396021Fa, not F. So by the Julian date code this block was made in Nov of 1974, but the 396021F says it couldn't have been made later than 72. It also has "J" heads, but that really means nothing.

So what do you guys think about the "8" and the 396021F?

regards,
bob

joe_padavano

I think you should ignore the "8" and look at the VIN derivative stamp, which will tell you EXACTLY what model year the block is from.

507OLDS

There are plenty of blocks made after 1972 that are NOT Fa blocks.Some say the Fa blocks do not have the provision for the z-bar stud.From my personal experience,the Fa blocks that I did have,did NOT have the the provision for the z-bar stud. The font style of the "F" did change before that.

bobb

Hi Guys,

Joe...I hear ya. But many times that VIN-derivative pad is unreadable. As such, I'd like to be able to identify 455 blocks another way.

Brian....thanks for the info. Now that you've confirmed that "F" blocks were made past 1972 the other info makes sense. But it does beg the question of what's the difference between the Fa and F blocks? There must have been something significant enough for them to change the casting number from "F" to "Fa".

thanks,
bob

J-(Chicago)

As Brian stated, there is no manual linkage provision cast upon the Fa blocks.
Look directly above the starter, on the side of the block.

Also, the Fa blocks had different crankshafts in them. CN.
Similar to the N crank, but with fillets on the ends of the journals.

442much

I found and bought a 1973 455 engine. The font was different to what you normally see and the numbers were 396021F. There was no "A" after the "F". There is nothing written in stone. I use the popular explanation on these blocks as a guideline, not as gospel. My T code 1976 442 block says 396021F in the familar font.

bobb

Interesting stuff to be sure. But J.....a different crank and lack of z-bar stud provision don't sound like a good enough reason to change the casting number. The crank shouldn't matter at all........the z-bar stud could. I guess Olds did stupider things....

I asked the guy to send me the vin-derivative on each of the blocks. We'll see if he responds. Since it sounds like the F blocks were made past 1972 I think Brian's theory of the single number by the julian date code corresponding to the year still works.

regards,
bob

bobb

The guy sent me the VIN-derivative code from the side of the block that had the 396021F and the "8" and "322" Julian date code. The code was 34M220544, which decodes to a 1974 block. So they did indeed make 396021F blocks past 1972! And Brian's theory on Julian date coding still holds! Mystery solved.

thanks,
bob

507OLDS

What is strange is how they eliminated the boss on the side of the block,but then they decided to start drilling more cranks for the pilot bearing. Last,year,at the Dick Miller event,there was a guy selling a bunch of engines,and one of the was a smogger 455,with this strange device on the side.It was a factory piece.It was a series of brackets,and the ball stud,mounted on the side of the block,which did not have the boss for the stud. So basicly,they eliminated the boss in the casting process,but then had to engineer a new way to mount the ball stud.Is that like taking a step forward & two steps back?

john garrett

i have two 425 olds and the way i found out is google the numbers promise you. It will give you what it is yours like mine 396021 F is a 1968 to a 1972 i gave four hundrend dollars for it about two hours ago and the man i bout it from said he took it out of a 1970 regency :john garrett from KENTUCKY

Texas Jim

From the OLDS INFO page, it stated that the "F" is '68 to '72, and the "Fa" is '72 to '76, and both "F" and "Fa" are 396021 castings. WTF? Out of all the (big blocks) engines that I've ever gone through, rebuilt/built, the Olds (455ci) is the "trippiest" by far over-all, considering everything. But it's a different breed and I like it f/ the fact that it's different. And I also like the big torque, even in stock trim.

507OLDS

There are 73-76 smogger blocks that are F,not Fa.I have one here from a 75,that is just F.I've had a few guys tell me that they have an Fa block with the boss for the z-bar stud,so maybe the "a" does NOT mean automatic.The smogger blocks are a great source for 4-spd cranks,as a lot more of them were drilled for a pilot bearing.No sacrifice in strength.As a matter of fact,there's a later crank in my 507.Eleven years,and it's doing just fine.It's a CN or N,can't remember,but they are the same casting number as the earlier N/CN cranks.I've also had a few that had NAK instead of N or CN,but the casting number still the same.

442_Mustang

I have an Fa block in my 72 that most definitely HAS the "Z" bar ball stud mount because it's in use.

2blu442

Yesterday I looked at some Fa blocks I have. 2 had the Z bar boss and 1 didn't. So the plot thickens!

All the Fa castings I've seen have the same F as the earlier blocks and just add the letter A. From the comments it sounds like there was a different font used in some Fa blocks?

bobb

Ok....so we know F blocks were made thru at least 1976. Do we know for sure Fa blocks weren't made before 1972?

regards,
bob

greenslade

he took it out of a 1970 regency?wasn't the first regency made in 1972?

D Appeldorn

did'nt they make the engines in production and when asembled to a car than it gets a identification number?
Exept for the F amd Fa?

The engines could be on the shelf waiting to get installed.
This is what i have with a other project of mine, a 39 engine in a 40ies car.
original .

Coltonis

As far as differences, I remember reading somewhere that an oil return passage was made larger on Fa castings.

Add that that to the mix with a grain of salt though.

507OLDS

They probably started casting the Fa blocks in late-72,for 1973,but with the whole strike thing in 72,maybe they were intended for earlier use. You do realize that the 73 Cutlass that we know today was supposed to be a 72. It sounds like I have a miracle child.