[superdutybob]

No question that it's a 74 auto trans. engine. The 73 on the paperwork is probably calendar year related, not model year. It has the correct carb and everything. Cool picture.

[toomanybirds]

Brew and Bob, tell me how you know it is a 74 engine?

I don't see enough of a carb in this picture to know the year?

We are talking about the engine shown on the assembly line with a worker, right?

[1qikta]

That would be Dick if it were V-10's

[Held for Ransom]

Originally Posted by toomanybirds

Brew and Bob, tell me how you know it is a 74 engine?

I don't see enough of a carb in this picture to know the year?

We are talking about the engine shown on the assembly line with a worker, right?

Yes, they are. If you look at the paperwork above the engine, you can see the Y8 assembly pick code. You can also see the 12 degree designation.

[Brewster]

1973 XD = automatic SD and in 74 it was Y8 for a SD automatic. The motor in the background is a D-port engine and not sure without searching ?

Hey Bob, Wouldn't that be correct for a 74 valve cover decal. Whens your birthday I'll punch one out for ya and that Dick you call your best friend () I mean Richard! ;-)

[ramair3formula]

Sure wood be cool if that was the engine for my 74SD since it was built in Oct of 1973

[MikeNoun]

Our resident assembly line guy (Keith Seymore) made a comment in another thread that he thought this picture (the assembly line pic of the SD engine on the hook) was obviously a staged picture, as the tie & white shirt guys would not be touching anything on the line unless it was an emergency. I always wondered if this photo was staged for the EPA to show that the white collar guys were watching the SD engines personally?

Back to my original question, I just wasn't sure if it was a 73 or 74 photo. I wanted to mark the picture accordingly.

[Rocky Rotella]

The engine following the SD-455 is definitely a ZN-code engine. All my factory-printed references show ZN available only in 1973, and as a 400. The SD-455 sheet says "Super Duty Auto 1973" and while it might be for the calendar year, I'm guessing its more closely related to the model year, especially if a ZN engine is following it.

Additionally, directly under the "Y8" on the SD-455 spec sheet is "487526." I don't recognize that as a part number and it doesn't appear anywhere in the 1974 Engine Assembly Manual. Could be the Engine Serial Number? If it were, it'd put it toward the end of the 1974 model year production. Otherwise, could it be a preproduction 73?

On a different note, the attached valve cover label shows XD with a initial setting of 12-degrees. Did it change at some point throughout the year?

[Rocky Rotella]

Also, isn't the valve cover timing spec label in the SD-455 picture an early 1973 variant?

[fiedlerh]

It appears that in 1973 they incorporated bar codes. I've heard 2 theories about the bar code.
It was to set engine timing accurately for emissions reasons.
It identified the engine code.
74 variant:

Anybody else have a stamp like this on their driver's side valve cover?

[toomanybirds]

Originally Posted by MikeNoun

Is this one a 73 or 74?

I have some news for you guys.

The engine in the assembly line photo is a 1973 SD-455!

What? You say it can't be? Y8 is a 74 SD-455 engine???

Well, often forgotten is that the 73 model year had two sets of engine codes. One set for the early, pre-emission change of March 15, and a second set for the new emission system after March 15.

The early emission SD-455 engine codes were Y8 automatic and W8 manual trans, yes, the same as the 74 engine codes. The 73 late production SD-455 engine codes were XD and ZJ.

So how do I know it is an early production 73 engine?

The next engine in line gives it away. It is a code ZN 400 4bbl big car engine. ZN was an early production, pre-emission change code. ZN was not used in late 73 or 74 engine codes. There is no way a 74 SD engine would be on the same production line as an early 73 engine. If it was a color picture, we would see the early light blue engine paint on these engines.

McCarthy's book is a little misleading on these details. His engine code list for 73 mixes together early and late codes, and his footnote incorrectly states that the early (310 horse) engine codes were X8 and Z8, they were not. The only place I have found X8 and Z8 is in some listings in parts catalogs published 1974 and later.

Someone stated that there was a date of 10-73, I have not found that date in this picture. I do see what looks like "1973" on the paper work above the SD engine.

Also, since this is one of the 310 horse engines, it never made it into a production car sold to the public. It could have been installed in one of the early test vehicles like the famous Car of the Year GTO, or the Grand Am that shows up in photos with the SD_455 decals on the fenders.

One last detail: timing for all SD-455 engines (early 73, late 73, all 74) is 10 degrees BTDC manual trans, 12 degrees BTDC automatic trans.

[toomanybirds]

Rocky, I just read your posts. It looks like you were on to the engines being 73's. But, I don't know how you were able to read the number "487526" I can't make it out.

It looks like the bar code printing on the engine sticker must have been a late 73 addition. If so, the engine in the red pre-production 74 is probably an early production 73 with the 310 horse camshaft. If that radiator hose wasn't in the way, I think we would see a Y8 code on the sticker.

[johnta1]

Early Chart of 73 Engines:

[Held for Ransom]

Yep, I just posted this in the other thread.
http://www.forums.maxperformanceinc....d.php?t=623532

[MikeNoun]

Yep, I see "1973" on the paper above the engine.

[ramair3formula]

I didn't mean to imply that I saw a 10-73 date sorry.