cylinder heads

[J & J]

Can someone explain the main difference between the 690/583 heads versus the Z-11 heads. Will the valley cover for the Z-11 fit the 690/583 heads? thanks to those that answer. J&J

[Ronnie Russell]

J & J, The 690s and 583s do not use valley cover. Z11 style only. Z11 heads require Z11 intake manifold and valley cover. Hope this helps.

[bluescreamer]

J&J
I concur with Ronnie about Valley pan. Also there is a difference with the
intake valve position. on a z-11 head the distance between 1# and 3# intake valve and the distance between 5# and 7# is .100 of inch farther apart. than a 583 or 690 head. They where moved to make room for the intake port on the Z heads. also the push rod hole is a round hole, thereby requiring a guide plate.
therefore when you install the head on a583 or 690 motor the valve pockets for the intake valve in the piston donot line up.:bang It will require machining larger pockets in all 8 pistons(elliptical circle). or you buy pistons that donot have a pocket in them and then machine the recess where it belongs. Been there done that.
As you can see it is not a simple bolt on project.
Allen

[Ronnie Russell]

Allen, Very interesting information. I have never had my hands on any z11 stuff. Probably never will. Just know the bare basics. Thanks for posting. :)

[dq409]

The Z-11 heads are night and day compared to the 690-583`s.
The Z-11 heads are also taller and have a completly different runner design among other design differences.

Z-11 intakes will only work on Z-11 heads,,,

Check out the pictures on my picture site for a side to side comparison of the 690 and Z-11 heads ,,,dq

http://www.picturetrail.com/gallery/view?p=999&gid=5984338&uid=1590826&members=1

[J & J]

Thanks for the info, but let me rephase the question. I am only interested in the water ports that the valley cover is used for on the Z11. Could one use the valley cover on a 409 engine with 690/583 heads? What I am looking for is a way to cover the center up, still use the water ports and build my own intake manifold that only hooks up to the intake ports on the heads. Also I will have to build a water cross over tube for the center water ports or shut them off completely. haven't got that far yet. Still working on the valley cover aspect at this time.

[Dond409]

Read your post about center water ports. There are no center water ports. The water ports are at each end. The rear ports are rarely connected. the fronts are always connected and are where the water exits to the radiator. The center ports that you are referring to are the exhaust cross over ports. These are usually used in colder climates to help engine warm up.

[bluescreamer]

J&J
I have a empty motor with 690 heads laying on top (in a engine stand.)
layed a 733 (Z11 valley cover) between the 690 heads.
You can seal the water ports ok, but would properly destroy the rest
of the valley cover to seal a fabricated intake of your design.
The bottom of the intake ports are below the edge of valley cover.
it would require extensive machining on a milling machine to mate a
piece of aluminum to create a intake and have it seal.
(waste of a good valley cover. this is my opinion.)

You would be better off by designing a totally new intake.
Make a new valley cover and water crossover, out of 3/8 or 1/4 inch
sheet aluminum. then build your runners and plenun
Allen

[dq409]

Ya have to go with Allen on this one!!

The taller Z-11 heads allow room for the Z-11 valley cover.
You don`t have this room on the 690 heads.

Sheet metal is the way to go as explaned by Allen,,dq

[impalamike.com]

Thanks for the great pictures DQ409!!

[region rat]

I had plans to try to butcher a Pontiac intake, by cutting it in half and adding a section in the middle to make the ports line up. Poncho motoe has closer bore spacing. Haven't checked yet to see how close the gasket area is. (This is on a Z-11) . When I try it. I'll post onfo. We are going to make a 2 piece intake for the 690 head. Sealing the valley cover will take a bunch of silicone. Bob

[J & J]

Thanks you guys. after studing the z-11 heads, my thoughts were to make a valley cover rather than try and redo a z-11 one. could block off the center exhaust ports. and get some square aluminum tubing and manufacture the water cross overs. Just time and money no big deal, if and when I get it done I will post pic's but don't hold your breath it is going to be some time. thank again.

[dq409]

I think Allen (Bluescreamer) made his own manifold and it works extremely well!!

[jim_ss409]

Thanks you guys. after studing the z-11 heads, my thoughts were to make a valley cover rather than try and redo a z-11 one. could block off the center exhaust ports. and get some square aluminum tubing and manufacture the water cross overs. Just time and money no big deal, if and when I get it done I will post pic's but don't hold your breath it is going to be some time. thank again.

I made a tunnel ram a few months ago and one thing that I would definitely not do again is use tubing to make the water crossover. I think it would be much easier to use an upside down "U" shaped piece of metal and weld the open, bottom part to the valley cover. I notice that most profesionally built sheet metal manifolds are made that way.
If you want the valley cover to be separate from the rest of the manifold you might consider building a complete setup that includes the valley pan, water crossover and complete side rails that go right up to the valve covers. (like the ones in the picture) Then you could make the intake tubes bolt on like a set of headers. The side rails of the valley pan would get sandwiched in between.
Here's a link that shows my home made tunnel ram... http://www.348-409.com/forum/showthread.php?t=7329&highlight=tunnel