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Engine compartment heat

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Engine compartment heat

Post by csmck on Sun Jul 09, 2017 1:04 pm

Is/has anyone suffering/ed from engine compartment heat causing fuel system vapor locking? How did you solve the problem

After driving on a hot day and shutting down, the engine compartment temp goes through the roof essentially boiling the fuel line dry. Makes

I'm running a chevy sbc engine with edelbrock 600cfm carb with 1/4 spacer between the manifold, a mild cam and a 4 core griffin radiator. Driving temps are normal range. I've taken to opening the hood after driving to give the engine heat a greater chance to escape and cool down faster.

I'm looking at adding a header blanket insulation, insulate the fuel line, and spark plugs.

Currently running the faux louvered hood, and would love to find someone to convert it to actual working louvers.

Charles


csmck

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Join date : 2017-06-18
Location : North Carolina

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Re: Engine compartment heat

Post by Hotrod on Sun Jul 09, 2017 10:13 pm

Make sure your fuel line isn't close to the exhaust.  The insulation will help, but much better not to get it too close to begin with. Unfortunately, there isn't much room to work with and moving the line may not be possible.

If the problem can't be solved with insulation, you may have to resort to a return type fuel supply.  GM used mechanical return fuel pumps to combat vapor lock.  That may help you, but you would have to install a return line all the way back to the tank.  Just about any car or truck from the 80's should have that type of pump.  The downside to the mech system is that when you shut the engine off the fuel can still boil because it's  not moving and cause hard starting problems.

You could also go to an electric pump.  It should be as close to the tank as you can get it and below the bottom of the tank.  This helps because the fuel in the line stays under pressure (instead of suction with a mech pump) and slightly raises the boiling point of the fuel.  Plus you have the advantage of the pump pressuring the lines when the key is turned on.  I use electric pumps on all my hot rods because I can prime the carb before I start the engine.  My cars usually sit  for long periods and the fuel can evaporate.  Running the electric pump a few seconds will fill the float bowl up and prevent unnecessary grinding on the starter.

The best system would be an electric pump in or near the tank  combined with a bypass regulator under the hood.  The pump will circulate fuel through the regulator and back to the tank as soon as it's turned on.  This will fill the lines back up quickly even if the fuel does boil off.  

With any return type system (mech or electric), the fuel will stay cooler because it is constantly being circulated back to the tank and never stays in one place long enough to pick up much heat.  Except for the line from the mech pump or regulator to the carb.
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Re: Engine compartment heat

Post by csmck on Tue Jul 25, 2017 7:20 pm

Thanks for the electric pump advice. I'm researching electric pump options; think I'll go with Edelbrock to match the carb.

Also having a local custom shop quote a vented hood.

csmck

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Join date : 2017-06-18
Location : North Carolina

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Re: Engine compartment heat

Post by Hotrod on Tue Jul 25, 2017 8:42 pm

One thing about the Edelbrock carbs is that they don't like fuel pressures above 5 PSI. I believe this is in the tuning manual that comes with the carb.

I usually run a regulator on them no matter what type of pump I'm using. They will suffer from flooding if the pressure is too high. I've had very good luck with the cheaper Holley brand regulators.
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