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650cfm holley onto the 12a

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Old 08-30-13, 09:20 PM
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650cfm holley onto the 12a

Bought the 650CFM holley on sale for $319 at Advanced AP, problem is that the stock intake manifold is way too small for it. Tried to buy an adapter but there doesn't seem to be one.

Anyone know the best way to go about this without spending another $300 on the Holley intake manifold? I was hoping the holley would be a "plug-in and play" kinda part, but it seems like I should have continued using quicksteel and plugs on my stripped nikki carburetor (which honestly is becoming a headache and a half)

It seems to be a controversial topic on whether to use a holley or not. Also my exhaust headers look exactly like the racingbeat ones, should they be the same quality perhaps? (only difference is a bit of rust from aging)
Old 08-31-13, 12:01 AM
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Also, just found this: Holley 17-43 Holley Carburetor Adapters

it doesn't have any specific info, but think that can connect a 650CFM holley to the stock intake manifold?
Old 08-31-13, 06:59 AM
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You'll need the RB manifold. If you want a "cheap" non nikki 4 barrel carb that'll work it's the holley 1848. The edelbrock thunder 500 is also reported to be a good alternative.
I would recommend a lot of thread reading before committing to a giant carb on an engine too small to make it work right.
Maybe search:
Holley 650 12a
Modded Nikki
Nikki jet drilling
Edelbrock thunder
Or variants of the above. You will then be able to leverage dozens, maybe hundreds, of years of combined experience to make a decision.
Old 08-31-13, 10:29 AM
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you could have saved yourself a lot of heartache (and maybe $320) if you had just searched a little. it had to be said. now i'll move on ....

a 650 on a stock 12A is overkill and a huge headache, to boot.

as said above, if you want to run a Holley, the RB manifold is your best solution unless you have the materials and tools to fashion an adapter. which, by the way, adapters used to exist, but I haven't seen one since sometime in the early 90s.

there is info in the link you posted. that adapter is for a 2 barrel carb, so it is useless to your cause.

all in all, take heed to Cookboy's advice.
Old 08-31-13, 10:43 AM
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^^^ a 650 is to large for what you are doing . I like the holley carbs but you will find that the 650 is not the carb for you unless you do a lot of mods . It's not just making it fit you need to make it work proper and believe me it will be a heck of a lot easier to adapt the 650 than to make it work proper . JMO good luck .
Old 09-01-13, 02:46 AM
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Originally Posted by Cookboy
You'll need the RB manifold. If you want a "cheap" non nikki 4 barrel carb that'll work it's the holley 1848. The edelbrock thunder 500 is also reported to be a good alternative.
I would recommend a lot of thread reading before committing to a giant carb on an engine too small to make it work right.
Maybe search:
Holley 650 12a
Modded Nikki
Nikki jet drilling
Edelbrock thunder
Or variants of the above. You will then be able to leverage dozens, maybe hundreds, of years of combined experience to make a decision.
haven't had time ( too exhausted from my graveyard shift) to take pictures, but I've tried fox's stripped nikki guide and my nikki looks like a midget monster now with random parts hanging off. Lots of air tubes are already quicksteeled.

going to see what I'm going to do though, my friends are controversial, people on the threads are controversial. Everyone is telling me that they are correct, and the other person is stupid. This 650 holley seemed like a bad idea, but I want to be sure about it. Hard to find an honest person to explain his experiences with the holley, and not just general theory-crafts/assumptions.

Basically I told my friend that in the long run I may want to upgrade the rx7 to a 13b or rebuild the 12a (and maybe look into adding another rotary on it)

so the holley was a sort of shortcut where I can just switch from the 12a to the 13b, which he said it was possible. Now, I'm starting to doubt his little theory.
Old 09-01-13, 03:56 PM
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Originally Posted by Arcolithe
Everyone is telling me that they are correct, and the other person is stupid. This 650 holley seemed like a bad idea, but I want to be sure about it. Hard to find an honest person to explain his experiences with the holley, and not just general theory-crafts/assumptions.

Basically I told my friend that in the long run I may want to upgrade the rx7 to a 13b or rebuild the 12a (and maybe look into adding another rotary on it)

so the holley was a sort of shortcut where I can just switch from the 12a to the 13b, which he said it was possible. Now, I'm starting to doubt his little theory.
the Holley factions in the rotary world are splintered, divided. there is no solidarity ... and I guess it makes sense to an extent. I remember back in the 90s, I saw A LOT of people doing CRAZY things with Holleys ... BIG Holleys! and the funny thing is they seemed to work.

you have some guys that have it all - all the pieces of the puzzle. then there are some that have the rotary stuff, but not the Holley stuff. then there are some that have the Holley stuff, but not the rotary stuff. some people believe "bigger is better" and can actually make it work (somewhat), others believe in correct "sizing." some believe that they need to be modified (like Racing Beat does), and again, others think it's bullshit! some people post their experiences in detail, some don't. solid information is out there, but you need a decoder ring.

unless you're a natural talent, the learning curve is huge though.

generalities aside, for your particular case what we have here is a stock 12A and what i'm assuming is an "unmodified" 650. even if modified to work with a rotary, the 650 is just too damn big for it. for reference, when all is well, that size carburetor will work with a Bridgeport 13B! I've got one to work "okay-ish" on my brother's streetport 13B. so, you see, even with your logic of getting one because you plan to go 13B, it's still not going to be easy for you to get seamless performance unless you're ported.

for your 12A, I think building on the Nikki is your best bet. much more consistent and unified information out there. much more support and less black magic. another thing I can say about the Nikki is if you find it frustrating and hard to make it work, you haven't seen what a Holley can do for your blood pressure and sanity.

if you do go 13B, then we talk 13Bs.
Old 09-01-13, 04:34 PM
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So if this one is too big (sure sounds like it to me!), what would be a good alternative?
Old 09-01-13, 05:08 PM
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just showed up in classifieds:
https://www.rx7club.com/1st-generati...setup-1045051/
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