[BBimp]

I have made my Cowl induction working. After i have done so, It boils the fuel in the rear fuelbowl when i stop the car. It can still drive for hour's and sit at idle,
But if i don't remove the airfilter/airdam when i stop the car when hot. The engine flods.

I have bought jet extensions and will install them and set the fuel level to stock(I raised it to max, at the rear bowl to awoid it leaning out on launch)

The carb is a Demon RS 1050cfm with electric pump set @ 8psi. pressure goes away when the engine stops

I am thinking on mounting 2 computer fans to cool the carb and make them run for 30 min. after shutning the engine off.

Anybody have better idea's????

 

[jburns]

Here in the North East USA, the gas formulation changes throughout the year. I've had "winter gas" do the exact same thing to me on a warm day in late fall or late winter before the formulation changes. What kind of gas are you running?

 

[BBimp]

I am running Shell 99 oktane V power Pumpgas (~94/95 US gas)

 

[rp930]

A wood carb spacer. Mine looked like a fountain before I put one in. 1/2" was plenty.

 

[BBimp]

I have 2 on with a aluminun plate between

 

[rp930]

Are they wood? The bottom one looks like it's phenolic. Wood is the best insulator.

 

[Robinls5]

What will cause the gas to boil= HEAT... On a 70 396/454 Chevelle with H.D. cooling or with Factory A/C, The fan blade is a 3947772 with a shroud and a Eaton clutch.
Why did I mention the above items? My one owner LS-5 M/22 Was boiling the fuel and vapor locking. After talking to a retired G.M. ( Chevy ) thermal engineer. He explained: Not only does the 772 fan blade fan & Clutch pull air through the 3or4 row Rad. That big 772 fan blade also evacuates the " SUPER HEATED " air inside the engine bay VIA Exiting at the right rear exhaust manifold and exiting at the left rear manifold.
That is why " ALL " the rubber pieces and splash guards and such that came on your car must be in place. With all the factory parts and pieces are in place your engine bay now has The " FACTORY STYLE DUCT WORK " just like a furnace in your home. The 772 fan blade moves a ton of Cu. Ft. of Air per. Min.
The under hood space must be sealed off so the cool air comes in through the heat exchanger and exits ( VIA FORCED AIR ) at the rear manifolds. If some factory items are missing under the hood you may have " Burbles or hot air spinning in circles " and not exiting.
Bottom line, It is all about air flow and directing the air flow.
More info to help make you KRAZY !
Bob
P.S. why does the hot air exit by the right rear & left rear exhaust manifolds? They generate the most under hood heat.
Side note--- ALL FORD--MOPAR-- & G.M. cars of the 60s & 70s with ." HIGH Hp." engines had " Multiple Blade fans & Clutches " & Shrouds,,,,,, NO EXCEPTIONS ! Also clutch fans on LS-5s&6s do not exceed 2200/2400 RPMs. On the plus side with a clutch fan Assmb. your engine revs. quicker, Also the clutch fan will keep the temp down in traffic.
The above information is for a street machine and NOT a race car. Race cars require a clean sheet of blank white paper!

 

[Keith Tedford]

I have posted elsewhere that the cure for our L78 engine was to add the heat shield under the intake, aluminum heat shield under the carb with a quarter inch thick gasket on either side of the heat shield and blocked the heat crossover. Aluminum transfers heat much quicker than cast iron and the carb does not need all that heat in the summer. It cured our problem. Our car had all the factory under hood pieces in place, the 772 fan and clutch were working fine. I never had this problem in the old days with the 427, so I am wondering it may also have something to do with the volatility of today`s gas. You tell me.

 

[Slick71ss]

Until you find a better solution, attach a piece of fuel hose between the 2 bowl vents. At the very top center of the hose cut a small hole to vent. This won't prevent the fuel from boiling, but should keep it from flooding the engine when it does happen.

 

[Bluegoose1970]

You could do like I am going to do, use a NASCAR style air duct incorporate into the carburetor heat shield, with the carb in the air duct. Cools the carb and extra room allows more air to filter, isolates it completely from engine compartment . The bad points are you rebuild air duct, make entrance points for fuel lines and throttle cables and clearance for distributor. Benefits are besides cool air you are cooling the incoming gas also.


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[BBimp]

Until you find a better solution, attach a piece of fuel hose between the 2 bowl vents. At the very top center of the hose cut a small hole to vent. This won't prevent the fuel from boiling, but should keep it from flooding the engine when it does happen.

I have that set up on it.
I has run the car with this engine and carb for 4 years now. The only change to this year is TRZ arms. Sanhuff springs and the cowl tray. It had the same problem before i installed the heatshield and the top wood spacer 3 years back.

 

[BBimp]

You could do like I am going to do, use a NASCAR style air duct incorporate into the carburetor heat shield, with the carb in the air duct. Cools the carb and extra room allows more air to filter, isolates it completely from engine compartment . The bad points are you rebuild air duct, make entrance points for fuel lines and throttle cables and clearance for distributor. Benefits are besides cool air you are cooling the incoming gas also.


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That might work. But it not real easy to make. If it's going under the carb it's also kind of under my nitrous system. it will be a lot of holes

 

[Steve439]

Are the fuel lines touching the valve cover?
Seems like every extra bit of heat to the fuel hurts...

 

[BBimp]

Are the fuel lines touching the valve cover?
Seems like every extra bit of heat to the fuel hurts...

They don't touch, It's the fuel lines for the Nitrous you can see.
The one's for the carb comes from the regulator thats on the heater box.

 

[Slick71ss]

Have you actually seen any performance improvement from the cowl induction setup?

 

[BBimp]

Have you actually seen any performance improvement from the cowl induction setup?

No i was at the track yesterday. but there timing system was down So no time slips

(I have a nother setup on my Impala that also feed the engine cold air and that works!)