Warbird Information Exchange

There are photos after the text, starting with the departure from Boulder.I visited my plane in the hangar yesterday. Most of the work is done. Ray and Tim have done an oil change, which involves about 12 gal of Phillips 25w-60, clean 3 screens, change 2 Champion spin on fliters, and an oil sample for analysis. Then remove valve covers to check head torque, and inspect for any wear. This oil leaves everything nice and clean and sort of a gold green color. And the heck with Elton John, the Queen should Knight the man who invented Merlin Fingers. Clean and check 24 spark plugs, rare original Lodge ones. Install a new air compressor, the previous one leaked oil. Air runs guns, supercharger shift, flaps and brakes, only the gear is hydraulic with an air backup. A couple of valves were changed, now the air system seems nice and tight. New Brackett air filter. This is a neat item, a piece of oil wetted foam cut just to size of the airbox, about 1x2 feet, and only cost $80. I have never been able to understand the logic of a Mustang owner who has an air filter on his old truck or airport car, but flies his $100,000 plus engine around sucking in dirt with no filters. If you think it is only dirty at desert locations try this. After the next airshow, go home and wipe the back of your neck and hair with a damp white washcloth, then look at it. Think what the enginge is breathing when taxiing out at Osh on the grass behind another plane. Next new 27" Dunlop main tires; the old ones had tread left, but were getting weather checked on the sidewalls. The Dunlop cores are great, will go at least 2 retreads. Tire wear on my Spit is very mild. Tim found 3 exhaust stackes cracked. They are Inconel, a heat tolerant nickel steel and require special welding. He did some very nice minor paint touch up such as leading edges and prop blades. We changed the battery, and haven't decided if we may use a different one. It's 12volt and Odessy makes some nice gell cell or RC types. It is a big weight and price advantage over a P-51 not to have to use the large 24v battery. Blew a bug nest out of the pitot. All the normal inspection of control cables, hoses, joints, fittings are done as well as the normal gear swing. Upon runup Ray found a leak in the engine driven fuel pump so it has been sent for overhaul. That is about it for now. The weather has been beautiful, warm and sunny. I think the Spit will come out ready to fly about the time the first blizzard gets here!

_________________
Bill Greenwood
Spitfire N308WK

What are merlin fingers? And are spark plugs even made today that would fit your merlin? I suppose you might have them made specially or something, but where do you get them?

_________________
"I knew the jig was up when I saw the P-51D-20-NA Mustang blue-nosed bastards from Bodney, and by the way the blue was more of a royal blue than an indigo and the inner landing gear interiors were NOT green, over Berlin."

They are rocker arms that ride directly on the overhead cam.

Boots: A area that can be a wear item on a Merlin or Griffon is the interface of the cam follower and the cam. A follower is like a rocker arm in many piston auto engines, except the Merlin has overhead cams, thus no pushrods or rockers. The follower rides on the cam lobe, it is secured at the end and pivots to activate the valve stem. Each cylinder has 2 intake and 2 exhaust valves, total 24. Rolls Royce used a thin chrome coating to reduce friction, fine when new and lubed well. If it wears out it can also ruin the cam. A Merlin Finger has nothing to do with what the Brits thought of Hitler, rather it is a follower modified with an extra smooth hard carbide pad to reduce wear. They are perhaps $6500 a set and worth every penny. A preheat and preoil helps also. An Allison solves this wear problem with roller cam followers, but if you are flying behind an Allison you may have a problem with extra wear from ME 109 bullets in your cockpit! Lodge platinum plugs can still be found, about $100 each and some begging, but they are not made any more. They are very reliable and durable if you don't sand blast them. There is a modern plug, I am not sure of the brand that fits a Merlin, but requires a different ignition harness. I like original if it is available.

_________________
Bill Greenwood
Spitfire N308WK

Another domestic company also made plugs for the merlin but we never could get 10 hrs. out of them.

Sully

Hmmm. Really? I don't recall any P-38 drivers or maintenance guys complaining about their Allison engines.

Gary

Thanks Bill!

Did I start the merlin Allison fight again?

*hides*

_________________
"I knew the jig was up when I saw the P-51D-20-NA Mustang blue-nosed bastards from Bodney, and by the way the blue was more of a royal blue than an indigo and the inner landing gear interiors were NOT green, over Berlin."

Bill:

I heard Ray is planning a move overseas?

_________________
Regards,

Jase
www.b26marauder.com
"I'm having a BLAST!!" 2007 CAF Wing Staff Conference

RIP Gary Austin..always in our hearts

How long have you been running Merlin fingers Bill? Are yours from Canada?

Nixon installed Merlin fingers in ours last winter.

We are very happy with them, and much cheaper that the roller cam followers that are available.

For those who are interested.

Merlin Fingers

http://www.airshowbuzz.com/files/photo/ ... 139171.jpg

Sully

The issue with the stock fingers is that the chrome surface that rides on the cam lobe can wear off, which is a bad day for your camshaft when it happens. So the folks at Merlin Fingers replaced the end with a tungsten carbide insert. I've been running them for years and have also been very happy.

Jack Roush's team now puts 3x the thickness of chrome on stock fingers and they have also had good luck with them. And of course they make the roller cam setup.

Way back when the Rolls Royce engineers chose the slider design rather than the roller design because it allowed them to keep the frontal area of the engine smaller, so they could make the cowling smaller for the engine. The valve covers on the allison engine don't seem that much taller, but that's the story I'm told.

Happy Thanksgiving everyone -- Jim B

Yak 11. I have had my Merlin fingers about 8 years or so, and they are the original ones from Canada, can't recall the name of the man who furnished them. I am kind of old fashioned, not the first guy to want every "smarter than Rolls Royce" item that comes up. But I think these are well worth it along with a preheat pad(very easy and cheap) for the oil tank and the Jack Hovey adapter to use spin on filters and a preoil pump. It seems the aftermarket J R pistons are also proving out. I have one set left of original Rolls factory new pistons for my next overhaul. I don't now why Rolls used their design, except it must have worked well during the war with near new engines. I have books on Merlin engine design and problems and this kind of wear is not mentioned. In service they started the planes every morning to warm up before a mission, and if sitting for days they could pressure oil them before start. Rollers are not unique to Allison, and are not fool proof. I believe I read in Aviation Consumer of a recent AD recall of a roller mod for a general aviation engine. I think the problem may have been end play or wobble, which is not usually a problem with the conventional type.

_________________
Bill Greenwood
Spitfire N308WK

Boulder, CO RegionalAirport, Oct. 30, 2007




Taking off....

Spitfire video

A low pass....


One exhaust stach removed to weld crack

Bill and Ray Middleton

Bill and Ray, conferring....



Aftermarket alternator in place of generator

Merlin engine

Oil tank at bottom of engine



Rolls Royce

If you wonder about engine color, mine is painted gold because it was overhauled by well known Merlin engine builder Jack Hovey and that is the color he likes to use. Another prominent builder, Mike Nixon paints his red. I believe most of the Rolls engines were originally painted gloss black. I don't like the bright color as well, but it does help show the source of any oil leaks. Does anyone have any info on other official Merlin engine colors? I am sort of thinking of using a light blue/grey the next time, almost like a primer.

_________________
Bill Greenwood
Spitfire N308WK