1. I have heard that the "late" 553 manifolds have larger runners. How do I tell the difference? My 553 manifold has the same (or at least really close!) port dimension with respect to my intake gaskets, as well as the intake ports on my ECZ-G heads. The manifold shows no signs of being port-matched. How do I tell the difference between the "early" and "late" 553 manifolds?
2. What is the REAL advantage of a 573 manifold? Are the runners that much larger to achieve a real power gain? I'm not racing, just curious if the 553 is going to choke out the 312? Is it worth picking up a 573?

Can any of you fellas help? Hopefully Ted or Tim can chime in on this, or maybe even Mummert?...

Oh, I am running 3-94's and tube headers (REALLY old Hedmans:cool

Thanks for the help...the thing that really sucks is I sold a NOS Edelbrock 573 about 5 years ago rather than lettiing it sit on a shelf...

Todd

http://www.y-blocksforever.com/forums/Topic23539-3-1.aspx?Highlight=573

I had seen that thread, and almost picked up a Weiand intake recently, but didn't want to go after it with no real knowledge.

If there truly is a late version of the 553 with larger runners, I would think this may be one, as the port sizes are virtually the same. My intake is in OK shape, but it has some corrosion at the t-stat housing/bypass hole. I wouldn't mind replacing it, but only if it really is an advantage, i.e. a 573 manifold...

    Just as a point of reference on my Edelbrock 573 unmolested manifold the ports are 1.93 x 1.61 inch as measured by my Harbor Freight digital calipers. Pete Sellers

Those are bigger than the ports on my 553...I guess I should probably grab a 573 the next time I'm at a swap meet. Seems like I've seen one almost every time I go...