[Excaliber]

I know some things about the high riser heads, but not all! I run them on my ERA.

Last built in 1964, outlawed for '65 (as the Hemi was also I think). Often called the "Tall and Terrible" heads with HUGE ports that require a matching high riser intake. The medium riser heads were the replacement in '65 forward and some say they do 'almost as well' as a high riser from that year on. "Almost' being a relative term when your a serious racer...

They will support 7000 plus rpm. VERY hard to find and the 'must have' matching intake increases the problem. I run a 2X4 intake, which I've seen offered for sale for as much as $1,500 for the intake alone. Note the heads and intake have no 'cross over' exhaust ports to warm up the intake\base of carb and do require special intake manifold gaskets. This is a serious 'all out' power type application.

Smaller ports generally offer better throttle response for the street, and a lower idle rpm. Of course a lot of this depends on your cam profile and carb setup as well. I run twin four barrels and a fairly healthy cam. My engine does not like to idle below 1000 or 1100 and I've tried several different carbs and two different cams, different compression ratios, etc. I figure it's most likely the high riser intake\heads that require the higher idle rpm (not a problem over all, just mentioning it). The cam profile pulls good from about 1800, perhaps a little high for some, and is 'done' around 6400 rpm. My OLD roller cam would spin to 7000 plus and the high risers worked very well indeed at the rpm range and beyond! I'm afraid I'm really not taking advantage of their flow capacity with the now milder cam (but the power is still VERY good)!

With the old motor (12.5 to 1 c.r., roller solid cam, drag race carbs) I could 'run it out the back door' in 3rd gear, motor screaming with rpm. Now I HAVE to grab 4th just before the line because the rpm just isn't there with the smaller cam.

I would guess there were no originals built or shipped with high risers, but no doubt some were modified with them. My particular heads\intake actually came from an original factory "Thunderbolt" drag car.

I'm pretty stoked to be running "Tall and Terrible" heads with dual fours. It 'feels good' running original parts as opposed to modern alloy heads.