[PAUL K]

Does anyone know what the Z code is for? Or maybe it's a N.

[johnta1]

Are these the 1968 heads?

Never seen the Z, but that doesn't mean much.



Some early heads had a 'X' or a 'O' on them. denoted different springs or chamber volume.

[242177P]

I believe it IDs which valvespring the assembled head was fitted with? Rocky was looking into the 670s having X and O stamps (I'm leaning towards that one being an auto or stick thing)

https://forums.maxperformanceinc.com...d.php?t=810453

[PAUL K]

Thanks guys. I recall there being discussion about the 670 heads (I think). The letter code would make sense to possibly mean a different valve spring on the head or possibly chamber size. I didn't think the letter code was a Z though.

These heads are 1968.

Thanks for the link. I wasn't having luck finding that.

[Half-Inch Stud]

Nice clean casting right there. Maybe a photo of the chamber to be sure. 428 HO?

[Aluminum Chief]

In 67 Z was for HO & X is Ram Air.

[steve25]

But that head is a early 68 that still has the air injection runner passing above the Exh ports .

Maybe they carried those designator's into the model year 68 that production for would have started no later then 8 of 68.

[OG68]

16 Heads dated February - April from my 68 WT 400. Both have the 'Z' stamp.

[242177P]

Originally Posted by Aluminum Chief

In 67 Z was for HO & X is Ram Air.

Nope, mine are stamped O. 400HO/auto. IIRC, your HO is a stick? 744 needs more spring, enter the X.

[johnta1]

Ed, your heads are what is original to the WT engine?

[OG68]

Yes, Strange brew, but all original.

The block was cast Mar 25, 68. Has the correct VIN
One cylinder head Feb 13, 68, the other April 22, 68.
Intake Apr 10, 68.
Car build date was 05A

This was my mother's car before given to me so I'm familiar with its history

[steve25]

The 744 Cam itself does not need more spring as compared to the 068.

It's the fact that the motors with these Cams in it had a 4 speed behind them and the factory knew that these motors would be driven harder and buzzed up higher then the automatic cars.

This is why they where given more spring

[PAUL K]

Originally Posted by steve25

The 744 Cam itself does not need more spring as compared to the 068.

It's the fact that the motors with these Cams in it had a 4 speed behind them and the factory knew that these motors would be driven harder and buzzed up higher then the automatic cars.

This is why they where given more spring

The 744 cam lacks a lot in design. It does require more spring pressure than any other Pontiac designed cam. The lifter doesn't want to follow the lobe on the closing side right after max lift..... It wants to "jump off the cliff" rather than follow the lobe. This causes the backside of the cam to wear prematurely. It's not uncommon to see scuff marks on OEM cams in that area..... Also most likely why the design of the "blueprint" 744 cams was changed.

However IMO it's the coolest sounding cam when used in a 400 with 1.65 rockers and four tube headers.

[steve25]

Its a interesting subject, because in 66 when the 744 cam was introduced the Tri-power 389s that they where used in got springs that where a single coil with a flat wire damper, and set up at basically a stock installed height.

The open pressure ended up being a few psi less then the standard springs from what I can see!

In 68 to get the 744 cam you had the manual trans requirement, you got the taller valves, and different springs in the 31 heads, with a seat pressure of 127 and a open of 296.

[PAUL K]

Originally Posted by steve25

Its a interesting subject, because in 66 when the 744 cam was introduced the Tri-power 389s that they where used in got springs that where a single coil with a flat wire damper, and set up at basically a stock installed height.

The open pressure ended up being a few psi less then the standard springs from what I can see!

In 68 to get the 744 cam you had the manual trans requirement, you got the taller valves, and different springs in the 31 heads, with a seat pressure of 127 and a open of 296.

Agree it's an interesting subject. They changed the spring spec again with the 48 heads. Obviously they were having issues with controlling the valves and crutched that problem with spring pressure. Possibly that may have entered into the discontinuation of the 744 cam.... The springs used on the 48 heads were stiff! I recall they went into coil bind early and had 340 lbs.of pressure .060 from CB.

[steve25]

With the rev’s 340 of open pressure will allow your taxing the stock cast rods pretty good!

[PAUL K]

Originally Posted by steve25

With the rev’s 340 of open pressure will allow your taxing the stock cast rods pretty good!

The 744 cam will be weezing for air with a d-port long before the rods will be taxed.

I know that Royal worked with the engineers to design the 744 cam. Basically what I've read is it was designed to help the d-port engines pull strong the last couple of hundred feet on the drag strip. That is where the 068 fell short. I recall Schornack talking about this in his book. He thought the 744 was a better cam than the 041. I'd agree, personally I've found the 041 to be a dead player in a 400 car equipped with a three series gear and a stock torque converter... but like you said, it's an interesting subject. To bad we're the only two talking

Just to be clear that 340 was .060 from coil bind. But if I remember correct that was the .271 lobe with a 1.65 rocker.