[toobroketoretire]

As my '71 with it's 454" has so much torque I very rarely give it enough throttle to open it's secondaries. And when I do my engine will fall flat on it's face for 6 long seconds until the stagnant fuel in the secondary bowl gets consumed. After pondering it for a moment I realized it would be better to have a "balance" tube that joined the front and rear bowls together.

It only required drilling and tapping an 1/8" NPT hole in the right side of both of the float bowls then using inverted flare 1/4" brass fittings and a balance tube. For appearance I dropped the balance tube down to the level of the 3/8" feed tube but I'm going to make another that sticks straight out.

With the two bowls joined together the fuel in the rear bowl can never stagnate like it has been. There have been several times when I needed full power when passing someone and had to wait 6 long seconds to get it.



Although the sides of the float bowls are only 3/32" thick it was plenty for the fine threads of 1/8" NPT brass fittings and then I also used epoxy on the threads to aid sealing. And then I also used o-rings in the fittings so now the o-rings are doing the sealing rather than the inverted flares; something I'm also doing on my main feed line at both the pump and carburetor inlets.

[toobroketoretire]

A first I suspected the stock #72 jets were causing my engine to load up so Fish sent a pair of #70 jets to me several months ago. But they didn't fix the problem as I experienced a 6-second flat spot yesterday when I gave it a full throttle in 3rd gear.

In the past there have been several times when I went to pass a truck (or two) or a string of cars and when my secondaries opened my rpm suddenly quit climbing. Then after a long six seconds power suddenly came back and it accelerated normally.

So as it's always a 6 second delay I'm guessing it's stagnant fuel in the rear bowl causing it and it takes six seconds to purge the dead fuel out of the bowl. Because once that six seconds passes and power comes back to normal I can give it a full throttle over and over again without any problems..............on that day. But then after several weeks of driving it gently it'll do it again...............for six seconds.

What do you guys think?

[fishslayer143@yahoo.com]

damn, thats a new one on me Toobroke..6 seconds? thats a really long hesitation ...and only once, then it works fine? strange.. my first thought was the needle and seat is sticking closed,fuel evaporates over time, and the bowl is just empty..you increase the rpm, fuel pressure rises and it unsticks, and takes a few seconds to fill ..but you re saying , you think the fuel boils repeatedly on shutdown , and is useless after awhile? it could be...

[Hotrod]

I've heard of, and even experienced, a secondary tip-in sag , but not for six seconds. Are you sure your float is not sticking to the top of the fuel bowl? Maybe lower the float some(1/8") The fuel bowl should always have fuel, even if it boils off from heat soak it should replenish itself when the float drops. This is baffling, but I know you will figure it out. Also, are you saying the fuel becomes bad after sitting for so long?

[toobroketoretire]

Originally Posted by Hotrod

I've heard of, and even experienced, a secondary tip-in sag , but not for six seconds. Are you sure your float is not sticking to the top of the fuel bowl? Maybe lower the float some(1/8") The fuel bowl should always have fuel, even if it boils off from heat soak it should replenish itself when the float drops. This is baffling, but I know you will figure it out. Also, are you saying the fuel becomes bad after sitting for so long?

This is something that I have never experienced with a QuadraJet. I had the sight plugs out about two weeks ago and the fuel levels in both bowls were 1/16" below the window. As these big blocks have so much bottom end torque I very rarely open the throttle enough to open the secondaries and then when I finally do it'll act just like the rear bowl is completely empty. Extremely low power for 6 seconds then it'll take off like a rocket ship.

With the REAL rough mile or dirt road I have to drive to get in and out of my property I don't see how the floats could possibly stick in any position. So rough I have had my cup of coffee flip completely upside down. And every time it does this it'll run perfectly the rest of that day and for days after. It only happens when I've driven it for several weeks without opening the secondaries.

[toobroketoretire]

A float stuck in the up position makes no sense as how would it get stuck in the up position in the first place? I have seen floats get stuck in the down position but never in the up position. And let's say it was stuck in the up position. When my secondaries opened I would immediately have full power until the bowl was empty and then the power would decrease and stay decreased because the float couldn't drop (a "stuck" float). But I'm getting no power the moment they open and then after a 6 second delay the power is gradually restored. So it acts like the fuel that is first being delivered isn't lighting off under high cylinder pressures and after that stale fuel passes and fresh fuel gets pumped in the power comes back to normal.

Make sense? If it never does it again then I'll know for sure the fuel was indeed getting stale; stale enough to prevent it from getting lit off in high cylinder pressures anyway.

[fishslayer143@yahoo.com]

you sure get some mysterious ailments on your car, Toobroke.. well, whether is was stale fuel or no fuel at all, which is still my theory, the balance tube should cure it... we will know in a few weeks.. just seems a short time for gas to go that bad.

[toobroketoretire]

Originally Posted by fishslayer143@yahoo.com

you sure get some mysterious ailments on your car, Toobroke.. well, whether is was stale fuel or no fuel at all, which is still my theory, the balance tube should cure it... we will know in a few weeks.. just seems a short time for gas to go that bad.

Are you saying you think the float somehow got stuck in the up position and then all of the fuel evaporated? Then after 6 seconds of full throttle the float got unstuck and gas started pouring in? So what would make it get stuck when it pivots up and down so freely?

In the past I've noticed it'll do the same thing but for a much shorter time (2-3 seconds) after driving it about two weeks without opening the secondaries.

[fishslayer143@yahoo.com]

I m saying the needle maybe sticking.. I just had a problem with my bike recently, 1 of 4 carbs would stick closed and 1 would stick open..damndest thing I ever saw .. 1 cylinder would flood and the other would starve.. cleaned them thoroughly and they still did it. I have no explanation how .. replaced all 4 needle and seats and it runs fine now .. but you make a good point, the road you live on is like an offroad dirt track.all that banging should open it.. still, gas going bad enough not to light off in just a few weeks seems strange , but possible I guess....I m sure curiou, lets see what happens

[toobroketoretire]

Here's my theory:

When gasoline begins to go "stale" what happens? Well, it begins to fail under high cylinder pressures. It will ignite under low cylinder pressures but when the pressure increases it fails to "light off"

How high are the cylinder pressures when the secondaries begin to open? Well, they're very high and will get even higher as the engine makes even more power

So when is my extreme loss of power happening? Right after my secondaries begin to open and goes on for 6 full seconds

What is my conclusion? My conclusion is the gasoline in my rear bowl is getting stale enough to not light off under high pressures as that gasoline sits in the bowl unused for weeks at a time under high-heat conditions.

Once that gasoline has been purged and replaced with fresh gasoline my engine runs perfectly for the next week or so then gradually begins to do the same thing as more time passes by. So I'm convinced the gasolines I'm getting aren't maintaining their abilities to "light off" very long.