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Author
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Topic: Not sure if secondaries are opening
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streetstang67
Gearhead Posts: 397
From: SC, USA
Registered: Nov 2002
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posted 08-05-2003 11:10 PM
   
I've been having a lot of questions about my car lately, just trying to get it "tuned" right. I wanted to check and see if me vacuum secondaries are opening under full throttle. I tied some fishing line to keep the closed and test drove, then cut the line off and tried again... no change. Is there a better way of testing that?
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ukracer
Gearhead Posts: 166
From: South Wales UK
Registered: Apr 2003
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posted 08-06-2003 05:46 AM
Could try a small cable-tie snugged up around the rod and pushed up to the vac. can. Then test drive and after, see how far the tie has moved. By opening the primaries fully (engine off) and opening the secondaries manually until the tie again touches the vac. can. you can see how far they open. Make sense? It worked for me. HTH
Cheers, Martin
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indyphil
Gearhead Posts: 2690
From: Senoia, G.A. USA
Registered: Jul 2002
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posted 08-06-2003 10:36 AM
What kind of carb is it? My edlebrock makes a distinctive sound when the secondaries open up. (and a distinctive shove in the seat of my pants)
It sounds like a high pitch rushing sound that changes pitch as they open.------------------
'68 coupe 289 C code
66 heads, edel 600cfm carb, performer intake, dual exhaust
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n2oMike
Gearhead Posts: 2694
From: Spencer, WV
Registered: Jan 2001
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posted 08-06-2003 10:54 AM
That's just one of the things I don't like about Holley's vacuum secondary system. They NEVER seem to open all the way, and it doesn't take much to make them totally inoperable. Too heavy of a spring, or ANY leak or blocked passage in the system keeps the 4bbl from opening up. In my opinion, use an Edelbrock for the street and a double pumper for a more 'racing' oriented setup. Leave the cheap 'generic' Holley 600 and 750 vacuum secondary (#1850 and #3310) units on the store shelf.  When you stab the throttle on either the Edelbrock or a double pumper, you know the 4bbl is going to be there! Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
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streetstang67
Gearhead Posts: 397
From: SC, USA
Registered: Nov 2002
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posted 08-06-2003 11:34 AM
How do I adjust the secondaries to make them open?
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Fastymz
Moderator Posts: 20708
From: Reno Nv USA M&M#1240
Registered: Apr 2001
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posted 08-06-2003 01:14 PM
You can buy a spring kit and keep trying lighter springs until it opens.First try this," Could try a small cable-tie snugged up around the rod and pushed up to the vac. can. Then test drive and after, see how far the tie has moved. By opening the primaries fully (engine off) and opening the secondaries manually until the tie again touches the vac. can. you can see how far they open. Make sense? It worked for me. HTH
Cheers, Martin " ------------------
SCOOP 2.26 60'S
14.9 @ 90.86MPH 65 coupe,351w,C4,Big Boss 429 hood scoop,8" 3.40 TracLoc. https://mustangsandmore.com/ubb/Fastymz.html
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