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I bought a 2 inch 4 hole Edelbrock spacer for my 289 with a 600 cfm Holley. I know the workings of a spacer (open for more area, 4 hole for more low end) but will I need to rejet the carb or what type of carb tuning will I need to do? Anyone have one of these on the car and what type of difference did it make? Anything for a little more power....
Thanks.
Al
 

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I have a 1" 4 hole on my 289 with a Holley Street Avenger 670, didn't have to rejet. On mine it increased low end torque and seemed to smooth out the idle.
 

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The spacer will only increase your velocity going through the carb. You will not need to re-jet, if the carb was set up correctly in the first place. A spacer does not change the fuel / air ratio.

If you have vacuum secondaries, you may notice they will be opening sooner, because you will have a stonger vacuum signal.

That type of spacer will help the engine build lower RPM's faster. Thats all. It should not effect the top end at all, maybe even help that out too....
 

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All the 4-hole spacer does is smooth out the column of air, so you get better velocity through the carb, like Mike said. You would actually lose vaccum from the increased volume if it weren't for this effect, (like if you put an open spacer on the engine)

You might tweak your idle some because you may need less fuel with the increase in vaccuum. Jets, you may or may not have to, theres only one way to know. Since you're increasing signal, you may even need less fuel if you already have it set up just right.
 

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On 2006-07-24 17:06, psivory wrote:
I have a 1" 4 hole on my 289 with a Holley Street Avenger 670, didn't have to rejet. On mine it increased low end torque and seemed to smooth out the idle.
Thats because you were overcarbed to begin with!
You carb guru you.
 

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Really? Where do you have the resources to back up that overcarbed statement?
 

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On 2006-07-31 19:16, brotherdon wrote:
On 2006-07-24 17:06, psivory wrote:
I have a 1" 4 hole on my 289 with a Holley Street Avenger 670, didn't have to rejet. On mine it increased low end torque and seemed to smooth out the idle.
Thats because you were overcarbed to begin with!
You carb guru you.



 

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Easy crutch. No rocket science. Just basic carb selection and overcarb fixes. The real question is why is the spacer needed to begin with? Max rpm engine is turning. Cam duration? So many questions, so little answers. I have seen the typed specs and it is not needed AT ALL. If it had a poor idle it was too fat for that little motor . I would run it on mine at twice the power level! Overcarbed is a common, very common mistake. That one cost 375.00 give or take. A 670 avenger has idle circuits to handle 350-427 cubes.
 

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Wasn't so much a poor idle, and I could be mistaken on the spacer smoothing it out as I have fine tuned it alot since then (but I am not at all a carb expert) It seemed to idle a bit high ( before the spacer, but since I added it, and tuned the carb as best I can, it idles at just under 600 in park and 500 in drive)
All in all I am happy with it, especially for $100 buckaroos!
 
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