Are the new edelbrock heads woth waiting for?

[Hudson Hornet !]

 Hello folks, I am about to purchase a set of eddy heads for my 431 stroker. I see edelbrock has a new head listed for the big blocks, the rpm xtreme. Does anyone know anything about this head? I am just wondering if I should wait for the new heads, or pick up a set of the existing 84 cc heads. Thanks for the help.

[Challenger340]

The RPM XT Head is the slated "CNC" Ported version of the venerable performer RPM Head. It features 2.20 Intakes in the CNC'd Chamber, as well as the enhanced port. The Casting was modified slightly to provide for the higher Divergence from the port window.

Edelbrick just picked up on "what" people(Race Shops) were doing to their RPM Heads, in more "Competition" oriented applications ?

It's no secret to them by now, that Porting Shops, were raising the Ports Divergence Angle .125" through to the Bowl, re-working the Bowl to accomodate, and then re-contouring the Chamber(unshrouding) for in excess of 300 cfm which fills a "niche" for heavier Cars(Velocity), 440 to 500"

It's still expensive to do by Hand Porting, (We charge $1,000 PLUS the re-build), so I suspect the "Edelbrick" CNC version will be vastly more "cost effective".

What are you doing with the 431 ?
Stall speed ?
Cam ?
Tire & Gearing ?
Rpm ?

[Hudson Hornet !]

Thanks for the reply

Here is the laundry list:

383- 431 stoker

Comp cams xtreme energy XE274H cam

4-speed tranny

6000 rpm max

3.55 gears

28" tall tire

1968 Charger

Hope this helps!

[tan top]

   .......

http://www.edelbrock.com/automotive_new/mc/cylheads/chrysler/bb_rpm_xt.shtml

[BSB67]

I don't think anyone has a set of the Xtremes yet, so there really is no good quantitative comparative test results out yet.  At least not that I'm aware of.

That said, the bigger intake valve, and the much better combustion chamber design favors the Xtreme, but they are more expensive.

[aifilaw]

440source is doing the exact same thing (big surprise since the head is almost identical in every way). I think they want 2000 for a set of those rather than the 900 for the set without the porting.

their flow numbers are:
Valve Lift:     Intake CFM:     Exhaust CFM:
.100"    75.0    72.9
.200"    156.7    124.8
.300"    219.8    166.4
.400"    266.2    198.1
.500"    298.8    219.3
.550"    306.2    228.6
.600"    314.9    233.3
.650"    320.7    238.2
.700"    320.7    243.8
.750"    321.6    248.2

and the original ones for reference were measured on the same bench between 15 and 40 cfm lower depending on at what lift. so they picked up between 7% and 10% flow. I'd say for $1,200 its a fairly decent deal, but the end cost vs. a set of INDY's, and the INDY flow rates dollar for dollar at that point are going to be up for debate.

[471_Magnum]

Hudson,

Back to your original question, for your application, the standard RPM head should be more than adequate.

Folks are using the out of the box head in applications significantly hairier than yours with great results.

[Hudson Hornet !]

Thank you all for the replies. THere are just so many choices one can get confused On another note, what do you guys think of the new thumpr cams from comp?  Are they just a gimmick or are they worth putting into an engine?