i'v seen good and bad feed back on the holly carb setup. Is it really worth it? I know where i can get the rb intake (witch i was thinking of getting with out the carb) and holly carb really cheap. Is it a waste of money>

 

The Holley carb needs some modifications to run with a rotary engine. If you can work with carbs, you'll be ok. Like many performance parts; there are pros and cons to them.

 

The manifold needs some mods if you want to use a Holley (or Edelbrock) out of the box.

The general idea is to cut a channel at the top of the manifold to connect both primary runners together. Also another channel to connect both secondary runners together. These channels help to smooth out the powerful intake pulsations present, especially at low RPM, on a rotary. The aftermarket V8 carbs were designed for a plenum style manifold, which is opposite of the RB seperate runner manifold.

Does anyone care to correct me if I'm wrong? I plan to run an Edelbrock 600 on a '74 spec ported 13B and I'd like to do it right the first time. Note: '74 spec is like a mild streetport half way between stock and extend ports.

 

The general idea is to cut a channel at the top of the manifold to connect both primary runners together. Also another channel to connect both secondary runners together. These channels help to smooth out the powerful intake pulsations present, especially at low RPM, on a rotary. The aftermarket V8 carbs were designed for a plenum style manifold, which is opposite of the RB seperate runner manifold.



Never channeled any of my manifolds; but I always had RB prep carbs.
Doing this mod is for non RB prep carbs? Just want to clarify.

 

yeah, doing the channels is so you can grab a Holley or Edelbrock off the shelf. It's easier to cut aluminum than to extensively modify a Holley.

 

RB preps their carbs to better deal with the strong pulses the rotary makes. I recently got my edelbrock pretty much tuned in on my engine and it loved to pull all kinds of fuel through it. I went all the way down to the smallest jets on the secondaries and it still wasn't enough. I finally took the advice given to me from a couple forum members, jeff20b included, and "converted" to an open plenum. When I did that, I found my cruise and light throttle drivability went down the drain, but the carb needed bigger jets to perform properly. So, I made a spacer with connected secondaries, but separated primaries. I have no real driving time on this setup yet, but I think it will provide a good comprimise to a full open plenum.

In a nutshell, open plenum deffinately works better with an out of the box carb designed for a V8.

 

i beleive the holly is a rx7 setup from mazdatrix

 

SORRY to inform you BUT Mazatrix buys alot of their items from Racing Beat and resell it in their catalog.
L8R

 

Just don't do it....

 

if its an RB one, and you can verify that, go for it

 

Holley carbs are very poor quality. Very low manufacturing standards.
But, there are a lot of guys running them.
My choice is currently a Yaw carb, but I have a set of Weber DCD's sitting in my garage for when I get bored with the Yaw.