can a vac. secondary work with high power
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Joined: Jan 2002
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From: jacksonville fl
can a vac. secondary work with high power
i have a tricked out vac. sec., but know little as to how far it can go in terms of making power? any advice would be appreciated. is anyone out there running a similar carb, running 11's, 10's?
Team Owner
Joined: Apr 1999
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: can a vac. secondary work with high power (red406)
The division 6 track champ on this forum runs a VS 750 speed demon solid 11.70 machine.
I always wanted to try a Demon 750 VS. I have run a Speed demon 750 and a 825 Race Demon. It took a little work to make them run. Both work good for me. it just took time to learn about how to launch from a power brake to WOT. with 10 inch slicks I could brake to 1500-1600 and i had to ease into it with a 3500 stall because it would burn the tires so bad or even bog. You just can't WOT a big carb with a single plane without a transbrake
I always wanted to try a Demon 750 VS. I have run a Speed demon 750 and a 825 Race Demon. It took a little work to make them run. Both work good for me. it just took time to learn about how to launch from a power brake to WOT. with 10 inch slicks I could brake to 1500-1600 and i had to ease into it with a 3500 stall because it would burn the tires so bad or even bog. You just can't WOT a big carb with a single plane without a transbrake
Melting Slicks
Joined: Feb 1999
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Re: can a vac. secondary work with high power (gkull)
My neighbor ran a vacuum secondary 750 Holley on a 468 cubic inch BBC in his 1969 GTO for years. This engine had powered a '69 Firebird to an uncorrected 10.01 second run at Bandemere (which is 5800 ft ASL). That's a mighty powerful engine that seems to do just fine on a vacuum secondary carb.
I've also been running the same type carb on my 465 cube Pontiac engine in my '68 Firebird. It loves that carb, and I can feel it when the secondaries open. The Poncho is built up and has 10:1 compression.
You shouldn't have a problem at all. Just make sure the spring's light enough to permit secondary opening when you want it to. Dial it in, and it's one of the most forgiving carbs you could have.
I've also been running the same type carb on my 465 cube Pontiac engine in my '68 Firebird. It loves that carb, and I can feel it when the secondaries open. The Poncho is built up and has 10:1 compression.
You shouldn't have a problem at all. Just make sure the spring's light enough to permit secondary opening when you want it to. Dial it in, and it's one of the most forgiving carbs you could have.
