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Dual quad tunnel ram wants to stall when turning corners
My two cars both have tunnel rams with dual quad Holleys. On one the carbs are inline and on the other they're sideways.
The one with the sideways carbs wants to die when turning corners. I have to keep it running with the gas pedal. No problems when braking. Just when turning. I can't tell if it's starving for gas or getting too much.
Since my inline set up doesn't do this, I figured there must be unique issues with sideways carb set ups I don't have knowledge of.
Any advice is appreciated.
Last edited by Cool95vette; 08-14-2017 at 07:42 PM.
Float and needle valve location would be a hint. In the photo, the carbs are sideways making the needle valves towards the front. The other vehicle would have the needle valve in the rear of the carb. So, when turning . . . . . .
And technically you have vacuum secondaries on cylinders 1,3,5,7. Primary throttles on the even side. Vacuum side would be leaned out, throttle closed when turning.
Float and needle valve location would be a hint. In the photo, the carbs are sideways making the needle valves towards the front. The other vehicle would have the needle valve in the rear of the carb. So, when turning . . . . . .
And technically you have vacuum secondaries on cylinders 1,3,5,7. Primary throttles on the even side. Vacuum side would be leaned out, throttle closed when turning.
I never gave thought to the vacuum secondaries. I have mechanical secondaries on my other car. Do you think swapping carbs between the cars and putting the mechanical secondary carbs on the sideways set up would solve it? It should at least equalize the left and right banks of the engine.
I would check float settings first. You turn right it starves for fuel? Turn left it floods?
Thats normally not an issue with center-hung floats. You have side-hung.
Just a thought.
just an interesting observation....thats an old manifold, it still has the oil fill and breather on the front of it....any idea what year it is?
Don't know the vintage. I'm guessing 70's. This is the intake on my other car. It's an even earlier design. I know they're not as good as modern ones but I thought they looked cool.
The one with the sideways carbs wants to die when turning corners. I have to keep it running with the gas pedal. No problems when braking. Just when turning. I can't tell if it's starving for gas or getting too much.
Common problem. We run into that all the time on road race cars with sideways mounted Holleys, and it doesn't matter if they're side hung or center hung. Those carbs in stock configuration don't have "whistles" in them. What happens is that when you turn a sharp corner, fuel sloshes towards the vent slot in the metering block, sloshes up the vent tube, and spills a slug of fuel right down the venturi. Install the vent "whistles" in both carbs and it will solve the problem.
To easily test to see if this is the issue, remove your air cleaners and install a rubber hose from the primary vent tube to the secondary vent tube - it will be a nice "arc" of hose between the two vents (the hose will prevent fuel slosh out the vent tube from spilling into the venturi during hard cornering - the fuel will slosh up the hose, but won't dump into the venturi). Do it on both carbs, and clamp the hoses in place onto the vent tubes. Cut a hole in the hose at the top of the arc to provide bowl vent - the carbs will flood if you don't cut a hole at the top. Then take the car out for a test drive and slam it into the corners. If the hose solves the problem, you need the "whistles" installed. If the hose does not solve the problem, there is some other issue, and I have no idea what I'm talking about...
Common problem. We run into that all the time on road race cars with sideways mounted Holleys, and it doesn't matter if they're side hung or center hung. Those carbs in stock configuration don't have "whistles" in them. What happens is that when you turn a sharp corner, fuel sloshes towards the vent slot in the metering block, sloshes up the vent tube, and spills a slug of fuel right down the venturi. Install the vent "whistles" in both carbs and it will solve the problem.
To easily test to see if this is the issue, remove your air cleaners and install a rubber hose from the primary vent tube to the secondary vent tube - it will be a nice "arc" of hose between the two vents (the hose will prevent fuel slosh out the vent tube from spilling into the venturi during hard cornering - the fuel will slosh up the hose, but won't dump into the venturi). Do it on both carbs, and clamp the hoses in place onto the vent tubes. Cut a hole in the hose at the top of the arc to provide bowl vent - the carbs will flood if you don't cut a hole at the top. Then take the car out for a test drive and slam it into the corners. If the hose solves the problem, you need the "whistles" installed. If the hose does not solve the problem, there is some other issue, and I have no idea what I'm talking about...
Lars
I tried the hose as you suggested. Still no change. Checked the floats. The fuel level in the bowls is right where it should be. The engine runs perfectly other than this issue.
Is the next step to swap carbs between my cars to see if they work better in an inline set up? I'm open to ideas.
Both the vent whistles and the jets are a problem. Put jet extensions on the main jets that extend half way through the fuel bowl. That way the fuel pickup for the jets will be centered and won't uncover either direction of turning. If you flatten the top of the jet extension tube it will also help as it requires less fuel to keep it covered.
Both the vent whistles and the jets are a problem. Put jet extensions on the main jets that extend half way through the fuel bowl. That way the fuel pickup for the jets will be centered and won't uncover either direction of turning. If you flatten the top of the jet extension tube it will also help as it requires less fuel to keep it covered.
Mike
I looked up the jet extension kit on Holley's website. It says they're for the rear bowl only. Can I use them on the front bowls also?
I had the same problem drag racing. The cure was jet extention tubes I had twin 660 center squirters
The tube goes out in the bowls and fuel sloshing never leaves the jets dry
I see in the holley book that they have two kinds. I used something completely different. They were a nylon or something slip on fitting tube. I was able to bend them to stay in the deepest fuel area
Another possible problem is your carb type. I don't like single feed with tiny end bowls. Sideways carb manifolds were made for clearance of BIG carbs.
08-14-2017, 07:39 PM
Dual quad tunnel ram wants to stall when turning corners
just an interesting observation....thats an old manifold, it still has the oil fill and breather on the front of it....any idea what year it is?
