secondaries won't open on holley 3310
- Thread starter 500duster
- Start date
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VS carbs are sensitive to how the base is tightened down. If the carb is not tightened down evenly, the base can twist a little causing binding. Use one hand to push back the throttle lever about 1/2 way and use the other hand to move the secondary lever up and down. It should move freely. If not, things are bound. Just a thought.
Thanks. I will check tonight
I checked for any type of interference with gasket or linkage and all is good. Held throttle half way open and blew air into passenger side venturi and secondaries open. The 380 horse crate motor does have a lumpy cam but that should not change venturi vacuum. I'm currently baffled. I'm going to drive this car to work tomorrow run it hard a few times and see what happens.
Rat Bastid
Dunamis Metron
I have seen on the dyno engines that wouldn’t pull the secondaries open.
The carb is meeting air flow demand. That’s evidently all it needs.
Inertia
Well-Known Member
What's your timing at ?
Initial and total pls .
Initial and total pls .
Missing diaphragm housing gasket ? If missing could be a vacuum leak at that point.
It wouldn't be the first time I've seen it.
It wouldn't be the first time I've seen it.
Try putting the check ball back in.
TT5.9mag
Two atmospheres are better than one
How do you know they are not opening? Are you filming with a go pro while driving with the air cleaner off? If not I suggest doing that. The paper clip trick on the secondary vacuum pod actuating arm is not very definitive. Film it and prove they are not opening
lemondana
BlackDart
This is why I like Thermoquads-you can always hear them opening. 
TQ's are excellent carbs. Unfortunately, many of us don't have spreadbore intakes nor the ability to get the old strip kits.This is why I like Thermoquads-you can always hear them opening.
MopaR&D
Nerd Member
Better to go with a Street Demon (I have one on my Duster and love it) or Edelbrock, particularly the new AVS-2.
thesiren74
Well-Known Member
Very easy fix! All you do is unbolt it and put on a mechanical secondary carb.
Ok. That's should work fine. What revision 3310 - ?
Is it all the way against the housing?
The secondaries will probably not open fully but only to the amount needed based on the velocity through the primary side. So even at 6000 rpm, depending on gearing (load), volumetric efficiency, etc. doubt the 340 will open the 3310 fully.
H'm.
Where did you test this? I can tell you that at WOT from approximately 3000 rpm up there is a measurable difference in acceleration, power, and ET when the secondaries are disconnected.
Not too big. I ran a 3310-3 on my 67 notch with 340 comp-280 cam, manifolds, and 3.23 gearing. about 3000 stall
I did tweak it a little for better idle and off-idle but not so much that it would have radically changed the acceleration performance.
Its possible something is holding the velocity back. If its not pulling hard enough on the primaries, it won't open the secondaries. For example primary jetting too rich or timing curve way off.
When you've eliminated the possible mechanical issues, we can come back to the possibilites of timing and jetting.
I have a Quick Fuel 450 VS on my slant 6 and I don't have to test it. I know that beeotch opens because it flat hauls ***.
Dale Davies
Well-Known Member
Vacuum secondaries eh. Is there a choke lockout for the secondaries. This would prevent the secondaries opening while the choke is on, even partly. Don't know much about Holley's but Rochester has this feature.
Inertia
Well-Known Member
MOPAROFFICIAL
Oogliboogli
Don't know if this has been figured out or not but..
Are you sure that they are not opening when you're driving it? You're not going to see them open by free revving it.
Are you sure that they are not opening when you're driving it? You're not going to see them open by free revving it.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Did anybody mention;
that if the gas pedal is not opening the primaries all/ or almost all, the way, the secondaries can't get signal, and the link-rod will be locked out?
Or if the cam-timing is out too far, then the pistons are gonna push a heap of AFR back up into the intake, slowing the in-rushing air to a crawl, reducing venturi-vacuum?
Or that if the exhaust is severely restricted, the overlap cycle will also pump up the plenum?
The point is this;
You have proven that the secondaries are working on the bench, so..... it has to be a mechanical issue outside of the carb.
Baring that, the same symptoms will manifest if the carb is pig-rich.
that if the gas pedal is not opening the primaries all/ or almost all, the way, the secondaries can't get signal, and the link-rod will be locked out?
Or if the cam-timing is out too far, then the pistons are gonna push a heap of AFR back up into the intake, slowing the in-rushing air to a crawl, reducing venturi-vacuum?
Or that if the exhaust is severely restricted, the overlap cycle will also pump up the plenum?
The point is this;
You have proven that the secondaries are working on the bench, so..... it has to be a mechanical issue outside of the carb.
Baring that, the same symptoms will manifest if the carb is pig-rich.
Last edited:
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
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I have both a 750DP and a 750VS.
The reason I retired the VS, is because I can't wait for the Secondaries to open. When I burp the throttle, in town, it is rarely for more than at most 2 seconds because 3 seconds from 30 mph is gonna put me up some poor unsuspecting soccer-mom's tailpipe.
So therefore, I bolted on the DP. Now, when I nail it, chit happens..... not always goodchit, but daymn it can be exciting.
did you check to see if the small o-ring style housing gasket is in place?
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