Smokey Yunick NOS 67 Z-28 MO 302

[wwchevy]

Just my opinion, but Smokey "freakin'" Yunick built the engine, if you can't trust Smokey, who can you trust???
I can hear it now on a Saturday night- Q: " Who built your engine? A: "Some guy named Smokey"
That engine is awesome and valuable, Congratulations on an incredible piece iron.

[iluv69s]

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on other head...can anyone decifer these?? what are the correct part numbers for the 67 Z pistons and cam? Thanks

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upon inspection in person looks like it says
"pistons 3917624"
"cam 3849347"

some of the numbers are a guess, but that seems close...

Does anyone know the correct published GM part numbers for the pistons and cam on the 67 Z-28s?

Thanks....

[juliosz]

You may want to check to see if it has the stock bore. I bought a set of .020 over 302 pistons from a friend that he got at Smokey's garage sale (he bought several sets). The set I bought has stock size ring lands but he also had a few sets that had really thin ring lands. I can't remember the GM part number but it was stamped into the dome of each piston. I would vote for at least disassembling and checking that everything is ok.

[Ngtflyr]

Based on what I spent yesterday doing (replacing the pan gasket on my Z).

I recommend replacing gaskets, my motor was rebuilt 12 yrs ago and sat in the Az heat, after running a few miles it started leaking from the pan. Call me crazy but I'm thinking it's a lot easier now than after it's in the car. Now I can get back to

[iluv69s]

I could not resist a few 'future' shots !! It was a Kodak moment..

At this point I am going to start with the factory 4 barrel at first, and from there I will have a base line....
But I sure as hell cannot wait long to throw a Duntov cam in this thing a a TI ign. with the xram and take it for a thrashing or two !!! It probably wont take too long!

[iluv69s]

Having personally owned over a dozen xrams and having seen many dozens, both in person and on the Net...I believe this to be the earliest 'production' GM xram intake manufactured..or atleast known to exist.

I will be using it someday to complete my 'Trans Am' package !! Cannot wait, but will have to for a while...

[iluv69s]

The bottom xram intake base is the earliest dated and production numbered crossram I have seen. It is dated April 1, 1968. only about 4 months after the first prototype crossrams were made by GM engineering with prototype o-dash part numbers. This intake came with the prototype oil splash shield underneath (which I show removed to see the dates and part number location). This intake has many characteristics of the prototype intake that did not make the final revisions for the later 'production' xram intakes.
The part number on the bottom of the base was soon after moved on later intakes to outside next to the winters snowflake logo..and the date code to inside the intake so it could be seen without removing the intake from the car.
Note the winters snowflake on a raised pentagon different from the later 'production' intakes. There are minor differencesthroughout this intake that are different than the early o-dash intakes and the later 'production' intakes...

[iluv69s]

The xram top is from the first batch of the earliest dated crossrams made inside GM engineering for the racers such as Roger Penske and Smokey Yunick. At first in this era, they were strictly backdoor top secret experimental pieces that only went to GM insiders.

Notice the o-dash part number (experimental)...
and the date Dec. 1967...

[iluv69s]

Hopefully I can get this baby going this year (century)..and eventually feel the 7500 rpm shifts and the dual holleys with the xram setup !!!

[njsteve]

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At this point, I'm not sue what more to do. Should I tear the motor apart and check every little thing? Maybe just a quick check and trust Smokeys expertise?? Suggestions please!!

Thanks, max

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If it has been sitting for any length of time absolutely take it apart and check things. Then replace all the gaskets. Regasketing and checking internal clearances doesn't somehow "undo" Smokey's building of the engine but you can be darn sure that not checking the internals and then wiping a bearing or ruining the cam or crank would really undo Smokey's building of the engine.

You have nothing to lose and everything to gain (peace of mind) by checking things now, otherwise you're going to be wondering forever if you should have done it.