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Vortec head port dimensions

 
Sirshredalot
V-6 Camaros rule!
Posts: 104
Joined: 01/05
Posted: 01/11/07 01:52 PM

Hey yall...been a while.

I am putting together a new combo for my Monza till it gets way radical enough for the Tunnel ram set-up.

What Im looking at is a set of vortec GMPP 170cc heads for my 327 to buzz around 6500rpm...but im thinking about the intake ports...Are they big enough to be covered by a victor jr intake?...or a prof-product hurricane?

Those intakes boast a 1.88x2.16 intake port and I was wondering if anyone knows how big a stock port is on the vortec heads?

Will they match or am I gonna have more fuel puddling issues and backfire issues?

Please and thanks guys.
God bless

-Shred

 

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oldbogie
I mow my lawn and find Chevys
Posts: 1195
Joined: 08/03
Posted: 01/18/07 12:11 PM

It isn't that Vortec ports are bigger, they're positioned differently set higher on the manifold mounting face. A non Vortec manifold will have problems making the upper seal. The lower part of the non-Vortec manifold will be below the bottom of the Vortec's port floor making a lip that interferes with flow. The floor of the port can be ground down to smooth the transition, but this is a sub optimal solution. The general fix is to whip out the TIG welder and add material to build up the floor of the manifold ports and to build up the top port flange, then each is machined to provide a smooth and air tight transition from the intake to the head.  

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Sirshredalot
V-6 Camaros rule!
Posts: 104
Joined: 01/05
Posted: 01/20/07 01:02 PM

I dont think that I mentioned it....but I was under the influence that edelbrock made a victor vortec. What I was talking about is that say I have a set of stock or mildly portedset of vortecs....would the port size of the race manifold leave a lip all around the port causing the fuel puddling?

PS. I think I found a set of pro-toplines to use instead of the Vortecs.

God bless
Thanks Bogie

-Shred  

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oldbogie
I mow my lawn and find Chevys
Posts: 1195
Joined: 08/03
Posted: 01/22/07 12:11 PM

Edlebrock 2913, right on.

Getting a port match with anybody's manifold and head can be pardon the pun’ish comment "a head ache" At the factory they try to spec. dimensions and alignment such that the manifold part of the port always errors to being inside the height and width of the head’s port. While this does cause a flow disturbance it is less troublesome than the mismatch of the head port being bigger or registration causing a wall of the head port to hang inside the wall of the manifold's port. On the top and side walls such a mismatch really interferes with flow in a very big way. On the bottom of the runner you not only get the same big interference to flow, but fuel puddles there as well.

Getting alignment really requires precision assembly techniques that can be replicated from first build up to all following tear downs and build ups. This means consistency in gasket thickness for the manifold to block and manifold to head as well as head gasket thickness, head and block decks as well. Included in this is registration of the manifold to head port gaskets, they have to be in the same place every time. This is important for two reasons; first when measuring or indicating port to port alignment the gasket can be a tool along with a coating of Prussian Blue to visually see part alignment by coating one side or the other aligning to the head or intake and assembling thru torque down. Then disassemble and see the imprint in the parts made by the bluing. The second technique is to locate a fixed point on the head and the manifold that can be used to measure the location of the ports referenced from that position. This is the so called "XY
Z Coordinate System" common to industrial machining process. But to use any of these alignment techniques, you have to insure that the parts always go together the same way every time you diss and re-assemble them. To do this you can use alignment pins, or on the manifold use a body fit bolt that goes the same way in the hole every time with no sideways movement. Once the positioning is standardized, you can grind or fill port edges to smooth the transition with a reasonable degree of trust that the parts will go back together the same way time after time.

Don't underestimate this, it's hard to do and get right.

Bogie  

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