madvette74
Well-known member
I am curious to know, if a mechanical secondaries will make more performance than a vacume secondary quadrajet? this would be for an automatic car.
quadrajet, vacume or mechanical
- Thread starter madvette74
- Start date
1979toy
Well-known member
The mechanical secondary carb. will feel snappier. If both carbs. are tuned correctly there should be little to no performance gain to the mechanical carb. It is harder to get the tuning correct on a mechanical carb. As long as both are tuned properly the vacuum secendary carb. will give you better gas mileage.
I have 3 vacuum secondary carbs. in the garage on a shelf and one mechanical carb on my car. I'm happy with my choice.
I have 3 vacuum secondary carbs. in the garage on a shelf and one mechanical carb on my car. I'm happy with my choice.
J
john1977
Guest
Didnt know you could get a Q-jet with mechanical secoundarys, would sure be interested in one,where do you get one?
ruby76
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- Jul 12, 2004
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- Corvette
- 1976 Red Coupe, Saint Louis C3 Shark
convert vac to mech
What really makes the qjet mechanical secondaries different than the vacuum secondaries? Is it the choke stuff/linkage on the passenger side, that doesn't let the butterflies open? From what I can see on my vacuum secondary qjet on my shelf, is that if you removed the electric choke stuff, the secondaries would mechanically open whenever you "mechanically" opened the throttle. The "upper" butterflies have an adjustable spring rate, so it could be adjusted to open quickly, so can you convert a vacuum secondary qjet to mechanical?
Just scratching my head
:
I had a mech qjet on a previous vehicle, it looks pretty identical the to the vac qjet on my shelf. only difference is the mech qjet had a manual choke with a cable running to inside on the dash. The "choke" stuff on the vac qjet actually has linkage that interrupts the secondaries from opening.
But like the previous posters have said, I think a properly tuned mech or vac should be same performance, or such little difference you'd never be able to tell.
What really makes the qjet mechanical secondaries different than the vacuum secondaries? Is it the choke stuff/linkage on the passenger side, that doesn't let the butterflies open? From what I can see on my vacuum secondary qjet on my shelf, is that if you removed the electric choke stuff, the secondaries would mechanically open whenever you "mechanically" opened the throttle. The "upper" butterflies have an adjustable spring rate, so it could be adjusted to open quickly, so can you convert a vacuum secondary qjet to mechanical?
Just scratching my head
:I had a mech qjet on a previous vehicle, it looks pretty identical the to the vac qjet on my shelf. only difference is the mech qjet had a manual choke with a cable running to inside on the dash. The "choke" stuff on the vac qjet actually has linkage that interrupts the secondaries from opening.
But like the previous posters have said, I think a properly tuned mech or vac should be same performance, or such little difference you'd never be able to tell.
S
SteveG75
Guest
All Q-Jets have mechanical secondaries.
The air valve controls flow based on demand but the throttle plates are mechanically controlled. As the air valve opens, it lifts the secondary rods and allows fuel to flow on the secondary side.
The air valve controls flow based on demand but the throttle plates are mechanically controlled. As the air valve opens, it lifts the secondary rods and allows fuel to flow on the secondary side.
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