Factory Holley carb?

[hecmanortiz]

Can a standard Holley carb be used on a 12A with an RB intake manifold? How much difference between a stock Holley and an RB modded one?

Thanks,
Hector

[FC Zach]

I'm going to say no and that's based off my own personal experience. I didn't want to buy their fancy glorified Holley so I used a regular 600cfm with vacuum secondaries. The engine wouldn't create the vacuum needed to open the secondaries and that fuel circuit wouldn't work even if you manually opened the secondaries. I called RB for help and because their fancy overpriced glorified Holley is specially built and proprietary, they will not give any information on it. All I got from them is that the base plate is completely different, some ports are opened, and some ports are closed? The jets are also smaller in the RB version as compared to what typically comes in an off-the-shelf Holley.

[mattallac]

yes you can for a stock 12a its a 465 cfm you put a threaded hose nipple in the primary float bowl side where the sight hole is for setting the float bowl level ,you will also need to make a bracket for the throttle cable and then make an arm and rod for the oil metering block .I have owned quite a few holleys and the only thing you need to find out is the jet sizes. Usually the RB holleys are set up a little lean on the secondary side(at sea level) and if its a vac secondary then the spring can be changed to open with less vac signal. RB can tell you what carb to use for motor size and port .If it was my car then a weber would be my pic. Better fuel delivery and no hesitation around sharp corners ,even with center hung bowels there is still a hesitation with the holley . Good luck.

[t_g_farrell]

Originally Posted by mattallac

yes you can for a stock 12a its a 465 cfm you put a threaded hose nipple in the primary float bowl side where the sight hole is for setting the float bowl level ,you will also need to make a bracket for the throttle cable and then make an arm and rod for the oil metering block .I have owned quite a few holleys and the only thing you need to find out is the jet sizes. Usually the RB holleys are set up a little lean on the secondary side(at sea level) and if its a vac secondary then the spring can be changed to open with less vac signal. RB can tell you what carb to use for motor size and port .If it was my car then a weber would be my pic. Better fuel delivery and no hesitation around sharp corners ,even with center hung bowels there is still a hesitation with the holley . Good luck.

Its not quite that simple or no one would be buying the RB prepped versions
and they wouldn't keep selling them. To my knowledge they modiy the base
plate, jets, floats, bowls (for oil injection), and a few others random gadgets.
Theres a lot of good ole engineering invested into the RB products, so I'm
sure they have a decent product. I bought the Dell setup from them 20 years
ago and have loved it. I've always been impressed by their attention to the
details on their setups.

Originally Posted by hecmanortiz

Can a standard Holley carb be used on a 12A with an RB intake manifold? How much difference between a stock Holley and an RB modded one?

Thanks,
Hector

You can, but its a lot of work to make it run flawlessly and you have to pick
the right size carb as well. By the time you finish twiddling with it and buying
special floats and jets and modifiying things, the RB won't seem so expensive.
It boils down to your time and experience with carbs. If you have the depth
of experience tuning carbs and the time, go for it. Otherwise buy the solution
that has many man hours of engineering already put into it.

[mattallac]

there are a few changes but all easy stuff ,size :465 cfm for stock 12a.I have owned a few of these carbs and not much is different ,and even with a center hung float bowl they still suck around a sharp corner (cut out)