3x2 vacuum secondarys
Thread Starter
Heel & Toe
Joined: Dec 2023
Posts: 22
Likes: 5
From: Stuttgart, Germany
3x2 vacuum secondarys
Hello, I have a 68 427 Tripower 400Hp,4 speed.
Driving the secondarys did not open. I took them out, made new shaft bushings and all gaskets.I tryed with compressed air in the center carb, like i have seen it by Harold Demes.But the outboard carbs did not open.
Now I bought 2 Holley spring kits #20-13. Installing the purple springs the secondarys did open. May be someone changed the springs, the ones came out have been plain.Still now I have them out and could not test it driving.
Is there a recomendation for this engine combo, what color is factory? The ones I took out are about like between Holley plain and brown in the pressure.
Thanks
Driving the secondarys did not open. I took them out, made new shaft bushings and all gaskets.I tryed with compressed air in the center carb, like i have seen it by Harold Demes.But the outboard carbs did not open.
Now I bought 2 Holley spring kits #20-13. Installing the purple springs the secondarys did open. May be someone changed the springs, the ones came out have been plain.Still now I have them out and could not test it driving.
Is there a recomendation for this engine combo, what color is factory? The ones I took out are about like between Holley plain and brown in the pressure.
Thanks
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,216
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
You just have to drive and test them, I forget which springs I had in there....Im using a full mechanical setup now. I would go with the lightest ones and see if you get a bog from them opening to quickly. you can test it getting on the highway without increasing the speed to high. Just keep going stiffer until the bog goes away. A proper setup will feel like a solid push as they come in. If you can get more of a punch when they come in with out the bog then I think that is the best setup
Thread Starter
Heel & Toe
Joined: Dec 2023
Posts: 22
Likes: 5
From: Stuttgart, Germany
the ones I had installed (stock or not ? ) have been so strong, that the secondaries did not open even driving up an hill under load. Also with compressed air in the center carb they did not open.
Race Director
Joined: May 2006
Posts: 18,737
Likes: 2,583
Hello, I have a 68 427 Tripower 400Hp,4 speed.
Driving the secondarys did not open. I took them out, made new shaft bushings and all gaskets.I tryed with compressed air in the center carb, like i have seen it by Harold Demes.But the outboard carbs did not open.
Now I bought 2 Holley spring kits #20-13. Installing the purple springs the secondarys did open. May be someone changed the springs, the ones came out have been plain.Still now I have them out and could not test it driving.
Is there a recomendation for this engine combo, what color is factory? The ones I took out are about like between Holley plain and brown in the pressure.
Thanks
Driving the secondarys did not open. I took them out, made new shaft bushings and all gaskets.I tryed with compressed air in the center carb, like i have seen it by Harold Demes.But the outboard carbs did not open.
Now I bought 2 Holley spring kits #20-13. Installing the purple springs the secondarys did open. May be someone changed the springs, the ones came out have been plain.Still now I have them out and could not test it driving.
Is there a recomendation for this engine combo, what color is factory? The ones I took out are about like between Holley plain and brown in the pressure.
Thanks
Le Mans Master
Joined: Oct 2010
Posts: 6,937
Likes: 848
From: melbourne florida
2023 C3 of the Year Finalist - Modified
The correct spring is the one that makes the car run the best.. the purple spring is a popular choice. What the factory installed should not matter as it was a compromise.
