Holley Vacuum Secondary Spring

Bruceynz

Bruceynz

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Hi Guys,

I have a 360 mag as you all know with a mild cam in it sitting on a airgap intake, has anyone had any experience setting up the spring for the secondaries to open and if I am going to turn the engine to say 5500 max! more like 5000rpm at what point RPM would you want them to start opened and be fully open?

My carb is a Holley 0-80457SA 600CFM 4bbl

I tried the paperclip thing and it keeps falling off, go to check it and its gone!

Thanks
Bruce
 
Oldiron440

Oldiron440

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It's been a long time, but my little 289 Ford liked the lightest spring so it opens soonest but I can't remember witch one it is.
It was a 600 Holley also.
 
Bruceynz

Bruceynz

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Ok I went for the 600 for low down response and since my cam is just a step above stock I am not pulling mega RPMs I wonder what they have in them stock??

From below maybe your white?

spring.JPG
 
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A

AJ/FormS

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You want them in as fast as possible while not creating a bog. This varies with; power,loading,gearing,inlet air temp,traction and a million other things. Get the kit and start with the purple spring. If it bogs or if you can see the nose drop or if you can feel them kick in, then go to the next stiffer. If it does non of those things the go to the yellows.
Don't lose the little cork sealing gasket between the little housing and the main body.
If you value your time, also get the Quick-change top.
As I recall you have 3.23s, which would make 3500 up around 35 mph, which,IMO is waaaay to late.I like to control the power with my right foot. So I want it to spin when I want it to spin and if it's too soon, well that has never happened,lol.
 
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Bruceynz

Bruceynz

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Ok I found on our local auction site a used quick change so I grabbed it, will be here next week and I bought a spring kit, should be here next week so I will be able to get into it next week some time, will start with purple and then to yellow seems it will be somewhere around there

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slant6billy

slant6billy

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My 670 Street avenger was sold to me slightly used. the guy said the secondaries were not opening, but he was sure about his motor. It had the quick change kit already. I did the paper clip thing and just had to put a slight bend in it. The fun thing with the quick change kit is you can test each spring to find the one you like the most. I was decided in a little more than an hour.
 
Bruceynz

Bruceynz

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ok I played with the springs, what a difference it makes in performance when you have it right! the springs go plain, purple, yellow, orange, white (white the lightest) I have settled on the yellow spring, went to the orange cruising along I hit the gas pedal to the floor and get a stumble, cough and a splutter and then its off, with the yellow spring its just pulls smooth and hard with no stumbles or splutters! I made a video of it tonight with the yellow spring, I only take it to 3500rpm and she still got heaps more to go!

 
Oldiron440

Oldiron440

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Run it like your going to use it, I have been breaking my junk in on the dyno, there flat tappet cams so I give them 20 minutes to break in the cam and give em hell after a cool down.
All my big blocks have run 7k but I have gone more conservative on the cams and only turn them 6500 now. Fist pull is to 6k then 6700 after that. My little Ford was built the same way, 6500 rpm.
 
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AJ/FormS

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Bruceynz said:
Think I answered my own question

View attachment 27763
Click to expand...
The mph will not match these exactly cuz they do not take into account the TC slip. If you want to figure your TC slip, you must have a very accurate SpeedO. Then run it up to 4000or so and let everything stabilize. Record your exact speed and rpm; say 40 mph@4000. Then slow down to say 3600, and nail it. As it passes again thru the former speed of 40 mph, grab the rpm number and then shut down. Say it was 44 mph.
And say the 4000rpm calculates to exactly 40 mph.
Then 44/40 =1.100 and your TC has exactly 10% slip at 4000rpm and 40 mph.
Therefore to be exact, you would either take 10% off the tach to get your actual WOT mphs
Or add 10% to the mphs in the chart
 
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