[zav6a]

Put the washer between the #3 cyl head and the rear flashing as described here in the past. Eliminated a 30 degree differential. Very gratifying for a nickel. Makes one think about the optimization possibilities. Certainly going to spend the time to tighten up the upper chamber.

 

[gmcjetpilot]

Thanks for the info

That is great, thanks for the info. Also check for casting flash in the fins in the center of the head area. It does not take much to cut the flow and raise the temp. Cheers

 

[frankh]

Hmmm

I got a 20 degree differential between my front and rear cylinders on each side. I have a well sealed up plenum. I also have a 3/16ths washer under the head on #3 cylinder.

#4 runs hottest (375F in cruise) , presumably because a lot of air is "stolen" for the oil cooler here...In other words if the resistance across the SW cooler is too low it may locally drop the air pressure here, mind you if the plenum is doing its job it should provide equal pressure accross the top of the cylinders.

I keep wondering about flashing...I did look for flashing but never saw any (ECI engine from mattituck) but maybe I was looking in the wrong place?

AS to the oil cooler I am wondering if I have too much cooling?...I mean does the Vernatherm device bypass the cooler once the oil temp is satisfied? I'm wondering if I might add a controllable door to the back of the cooler to preserve some more air for cylinder cooling/drag reduction.

Any thoughts?

Frank 7a sam Jmes cowl/plenum. 13 hours and he's thinking about modifications already...

 

[zav6a]

More cool

My #4 runs the coolest. I attribute that to a little less work being done (I.E. fuel burned) by that cyl as it has the shortest (poorest tune) exhaust stack with an x-over exhaust system. My AFP fuel injector nozzels are balanced to peak within .1 gpm fuel flow and the two short stack exhaust cyls needed 5 percent less fuel.

I have a firewall mounted oil cooler with 4 inch hose that takes off over #4. It gets just enough air as oil temps can run up to 220 if I'm a quart low and it's 90 or more.

Vans upper plenum and openings (for an O-320) are probably relatively large allowing fairly thorough or even presurization over all of the cyls. Witness the reaction of mine when I added a single washer behind #3. Apparently there was plenty of differential pressure there - just needed a channel to funnel through. By the way, I did not see a corresponding rise rise in pressure in the other cyls when #3 cooled.

 

[TX7A]

Described where?

Put the washer between the #3 cyl head and the rear flashing as described here in the past..... .

Not flying yet, but I'm having a hard time finding info about this washer thing. Sounds interesting.
Can you point (link) me to the right thread?

Thanks

 

[zav6a]

Washer

I have not seen a thread other than what George mentioned. There is a small bolt that secures the flashing for the back of the plenum that screws into the back of the #3 head about 2 -3 inches below (towards the crank) from the valve cover surface. Without the washer, there is zero clearance betweent the flashing and parts of the head. With it, the width of the washer.