Thanks gentleman for those insights.

Jeff

Kent:   The fairly large oil cooler has always been fairly close to the left main spar (just enough room for the aileron control between them).   No holes in the main spar, of course.   Air passes downward through the cooler and out the underside of the lower cowl.     -8 hydraulic ducting.

I have never had any problem with oil temp or CHT.       I do need to smooth out the air flow from the NACA duct to get a more even CHT from #1 to #4.     It just takes time that I do not have.

Kent and Jeff

Yesterday I realized that I was falling asleep when I finished (2) so there is more:  

First mistake: I have a very heavy Catto 3 blade prop on a 6" prop extention.   THAT makes things difficult.  Should have a 2 blade.   Eventually I will sell that prop.

3. Several years ago I knew that many builders had trouble with the CG and were extending the nose.   At that time I cut off the nose and extended it just over 15 inches.   The space available was filled by a heavy battery angled slightly to fit.   A U-shaped SS part under the nose serves as a tiedown and adds weight.

That was not enough so I put many tools (in sturdy bags) that I might potentially use plus other items like a container of DOT5 (A friend almost lost his Longeze due to a melted brake line), a nose wheel, tubes for the mains, owners manual, can of oil, empty plastic bottle to fill with water if I used the oil, etc.   That made the CG close.   Then put 4 1/2 pounds of lead shot in a tiny chamber at the very front and sealed the chamber with 1 layer of glass.   Almost there.   Put about 10 rolls of dimes/quarters in available space between the lead chamber and the battery.    THAT did it.

Then a buddy showed up to fly it.  He is a lot heavier than I am so I took all of the tools out.   With great hope it was flown.     Don't tell the FAA but I might have been a passenger to go for lunch.   Anyway some experimentation showed that I could not get into the back seat because the RAF location for the step is in the wrong place.   Bought a Wilhelmson electric nose gear (with nose off the ground, I can easily get in the back).   Took more stuff out of the nose compartment and have a testable CG Longeze.

Buddy flew it.   It is now a legal airplane.   Am discarding my crappy cowling to put on a lighter upper cowl that became available.   Will make a female mold and new lower cowl if I live that long (I am pretty old).   I am short so a removable backrest moves me forward a bit and helps the CG.  I have to weigh it empty and with me and the backrest in it and recalculate the CG.    Maybe I can get rid of the 4+ lb of lead.  

May you have clear skies and tailwinds.

On 12/2/2019 at 11:00 AM, jridge said:

Can you elaborate on what you modified to keep the CG in spec when you converted to the O-320?

Your profile says you are building a Long-ez.  You can lengthen the nose and build-in space for a 25AH battery, use an electric nose lift, keep the oil cooler forward in the cowls and as Bruce suggests, use EI in place of rather heavy mags.  Even so, I am 225-230 and I still had to use about 15 lbs of shot just ahead of the rudder pedals to get a satisfactory stall response although I probably could have operated without it.  You might also build-in some space for weight closer to the battery.  My smallish friends without the long nose need even more weight--25-30 lbs to balance with an O-320.

Jeff, I do not recommend any of the following but what I did and problems that resulted:

1. The heavy alternator was removed and a much smaller alternator from B & C was installed on the usual pad for the old type vacuum pump (that nobody uses now).   That seemed a good idea for 2 reasons as the B & C unit is MUCH lighter and the heavy alternator was much farther from the desired CG.   Problem:   the B & C unit is too long for Longezes (i.e. the firewall is too close to the engine.   So much of the upper part of the firewall was rebuilt with plywood and SS sheet.   I suspect that I could have used thinner SS but it is strong.   The process was VERY time-consuming.   I got rid of the fanbelt, 2 heavy brackets, heavy bolts, washers, nuts, and some wire.

2. Replaced a very old E.I. with a Plasma II from Klaus S.   I think there is a weight saving there.   Anyway the Plasma II box is behind the passenger's head so is protected from the heat of the engine and it is closer to the CG.