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DATE

PROCESS

HOURS

CATEGORY

11-22-03

Corvair  - relocated AeroCarb

3.0

engine

DETAIL:

*EDIT 4/2004*  I no longer have the AeroCarb.  There were several issues that I could not get worked out.  I felt it best to get rid of it and I bought a 0 time Stromberg NAS3A1.  I no longer endorse the AeroCarb for use with a Corvair, but bear in mind I only have about 15hrs worth of run time on it, so my "endorsement" isn't worth much anyhow.

I was having difficulties with my AeroCarb being mounted above the engine.  In that position it was required that I run a fuel pump to get the fuel to it.  The AeroCarb is happy at about 1.5 psi of fuel pressure so I had to regulate the fuel pressure from the pump to the carb.  I bought a Holley fuel pressure regulator and a cheap fuel pressure gauge.  Try as I may I could not accurately get 1.5 psi.  I was getting anywhere from 3-8 which is way too much.  The engine was running so rich it was running very hot.

Another problem I had was the carb has a tendency to drip fuel if it doesn't fire up soon after cranking it over. This puts raw fuel and fuel vapors right on top of the motor.... not a good thing. 

I decided to relocate the carb to underneath the engine in an updraft position and go with gravity feed fuel system.  I bought some aluminum tubing and began the transformation.  Within a couple hours I had the new system ready to test.

The next morning I took the test rig down to Falcon Field for a test session.  WHAT A DIFFERENCE!  With just gravity pressure the engine was running MUCH MUCH better.  CHT temps were anywhere from 340-390 depending on power setting.  Idle was smooth at 600 rpm and full static was 2750 rpm.

I ran the engine for a full 1.1 hours at various power settings. I had to switch to the #3 needle to get the full power mixture set properly.  With the #2 it would lean out on the high end. Now it's running somewhat better.

In the pics below you can see the fuel pump is still being used.... for now I'm using it to transfer fuel from my 6 gallon jug on the floor of the trailer up to the 2 gallon header tank that gravity feeds the AeroCarb.  I fill the header to about 1.5 gallons and when it gets down to about .5 gallons I stick the pickup line in my main jug until it's back up to about 1.5 gallons.  What I need to do is put a model plane wheel collar on the line and adjust the set screw until it pinches the pickup line just enough to even out the flow so the fuel pump will be putting fuel in the header tank at the same rate the carb is using it.

For now I think I'm done fiddling with the engine.... now it's time to run it and break it in.  I plan on running it about 2 or 3 hours a week for the next few weeks. Then it's time to begin working on the wings!!!