So I was looking to see what the community might think of this. I am currently driving a 81 gs with a stock port 12a and a completely stock nikki. I may be able to get a rb holley manifold and holley 390 for cheap (150-200) and I was wanting to see if this would be a good upgrade. I do already have a custom exhaust that is a simple 2 1/2 inch straight pipe hooked up the exhaust and ran to a stock muffler (no headers, silencers or anything like that) so what power gains could i reasonably expect? Would this still work if i street ported in the future? Also if anyone has a good suggestion for a fuel pump/regulator set up as i know that will need to be changed. Any help would be greatly appreciated!

 

I think it would be a downgrade. Save the money for a header and presilencer first.
A Nikki can be easily modified to flow more air and fuel while maintaining better driveability. Read. Then read some more. The light will come on!

 

why would i want to change the exhaust? this is pretty much as free flow as it gets??

 

Separating the exhaust pulses and joining them later in the exhaust is what will make noticable power in your 12a. Right now with the stock manifold and straight pipe you are only realizing about 2/3 of what a header and proper exhaust will give you. A stock nikki and a holley 390 have almost the same cfm...a holley 465 would be at least where you want to go for a decent bump in power. Its tempting because its cheap but if you are gonna do it all over again a short time later how much money did you really save??? Spend a little extra on the correct parts upfront and save for a turbo II swap for later lol

 

well it now would be even cheaper as i ended up getting the carb for free, the switch over now would cost me about 80 bucks and thats just for the manifold which if i went for a larger carb i would have to have anyways

 

I also think i didnt explain my exhaust well either, there is no stock manifold on this either. It was a complete custom exhaust made by the previous owner who was a metal fabricator and is two separate 2 1/2 or 3 inch (cant remember of top of head) wielded to a plate that bolts right to the engine and is ran straight out to a muffler

 

Your original post said "no headers..." so I just assumed... do some more research on what is an upgrade and what might give you problems down the road in terms of driveability and tune. your nikki and "metal fabricator's exhaust" might be better. I truly think an unmodified holley 390 is not going to be the upgrade you want it to be.

 

try an edelbrock 500 AVS.

 

What all do you have to do to an eldebrock 500 carb to get it to run right on a 12a? Is it a lot easier than a holley? And how does it compare to a racing beat holley?

 

that is what i was going to ask as well. My plan for this was to go ahead and do the install so I would have some experience on the holly and due to the fact I already have it even if it wont be a big power gain and then once i ran it and tinkered for awhile then upgrade to a 465. I know i will have to upgrade the fuel pump and add a regulator, does anyone have a good suggestion on this??? Thanks for the thoughts from everyone so far!

 

I've heard the Edelbrocks work well and are easy to setup for a rotary. Hopefully someone with
experience with it will chime in to fill in the details.

The holley setup will be a challenge to get right for a rotary. RB does a lot of tinkering with the
465 and mods it in various ways to get it to work smoothly for a rotary. I think taking an off the
shelf holley and getting it working well is going to be more work than you may be prepared for.

 

does anyone have any idea on some of the things rb changes to make them run smoother. Then tuning am not stressed about to much due to i have my father who will take car of most of that who has been a master level mechanic for 25 years with a full shop at his disposal and has a good bit of experiance with tuning carbs for various cars

 

Do a search, its been covered before.