I know in theory they should be the same (outside of ports, bolt holes...etc), but which performs better, and how well do the ports on the Vortec Manifold line up with the ports on the heads? I've seen some really ****TY manifolds for vortecs that cover maybe 20% of the port... is this an issue with the vortec RPM manifold, and is anyone making big power with it?

Looks to me like the vortec heads offer more "Out of Box" potential with sain cam lifts.... but if the manifold becomes a problem, that would SUCK.

 

You have to use a vortec style manifold with a vortec head

Don't try to adapt a conventional style manifold to the vortec heads. It's not worth it. U won't get the benefits of the vortec head with a mismatched manifold.
The Vortec style Performer Rpm intake has a very good
port match with the vortec heads. No mods nessessary there.
Just replace the valve springs and shorten the valve guides for
cam lift clearance and your ready to bolt them on with the new manifold and self aligning rockers. Any cam with .450" to .500" lift will do the job.
Match the cam duration to your intended operating range
( converter stall speed, rear gear ratio) and you'll have a strong runner. Try to maximize the final compression ratio for the available pump gas. If your pistons are say .025 to .045"
down in the bore, use a thin steel heads gasket (.015")
as opposed to a .038/.041" composite gasket. 9.8 / 10.0:1
cr is good.

 

The hell you say? A vortec Manifold ith Vortec Heads... but the gic....it's just so extreme....

(Dripping with sarcasim)

What I was asking was IF the intake ports lined up with the Vortec heads presicely as they should with the Vortec RPM manifold....

Simply logic would say "Yes".... however, I've seen two carb manifolds for vortec heads line up very poorly... and YES, they were meant for vortec heads.

*IS THIS A PROBLEM WIT THE EDELBRCKS VORTEC RPM MANIFOLD?*

 

Hopefully they fit better than the ports on the RPM Air-Gap. I had to port match the intake on one side and the bottom of each runner because they were off. The runner entries just sat in the gasket high and to the left (or right) can't remember which way. Defintitely off to one side though.

 

Thats a common problem with Edelcraps in general. They have alot of core shift and quality control problems.

GM makes a Vortec manifold.....you can look into that as an alternative.

 

Don't know if your getting a genuine Edelbrock product.
All the ones I've seen have very good port match out of the box.
I remember some old torkers and such from the 70's that left a little to be desired, but every recent edelbrock I've layed eyes on has had good quality. The best thing to do is inspect the manifold befer you buy it. If the ports are noticably offset on the casting
then don't buy it.
There has beenn some copy-cat manifolds come on the market
lately so that may be a problem (bogus offshore parts)

 

Quote:
"GM makes a Vortec manifold.....you can look into that as an alternative."

He He! Edelbrock makes that one too!

 

Mine IS genuine Edelbrock, not a knock-off. Fairly new manifold since the RPM Air-Gaps have only been out for a little while. I bought it brand new a few months after they were released. Maybe that was the problem . Maybe they had not got the QA kinks sorted out then. To me I didn't mind since they were going to be port matched anyways