Dan Vincent

I've been posting pictures of diesels on the diesel forum and was just told about this 1/2A section.

Here are some Bill Atwood designed engines.

The 1949 Atwood "Wasp" .049 was designed by Bill Atwood and Bob Holland. When they split up in the early '50's Bob Holland kept the Wasp name and later marketed as the Holland "Wasp." The Wasp was the first high-performance .049 engine.

The original Atwood .049 featured a heavier (stronger) crankshaft and larger porting. The tank was similar to the Wasp but picked up fuel from a hole in the left side of the tank rather than the low pickup tube as on theWasp.

The Atwood Shriek had improved performance over the original Atwood .049 with a glo-head instead of the previous separate head and glo-plug.

The 1954 Atwood .049 had a shortened case with a long prop driver. This setup used a prop screw rather than the threaded shaft on previous Atwoods. This was about the same time as Atwood started building outboard engines so it is my belief that Bill wanted to lower the flywheel on the boat engines and had to make the modifications to shorten the case and made up the length on the airplane engines with a longer prop driver. Note this engine also has a fuel tank and separate backplate, making a 2-piece tank instead of the previous 1-piece designs.

BMatthews

Nice stuff Dan. And NIB as well. Are these here and the other thread all yours? If so my hat is off to you for a fine collection of 1/2A mills.

At one time I thought it would be quite neat to collect all the 049's ever produced. It seemed reasonable at the time as the 049 stuff did not seem to be so collectable as the other sizes. Sort of under the radar so to speak. And then the idea sort of faded away when I found out just how many there were.

ajcoholic

My Feedback: (10)

Hey Dan, Andrew Coholic here - dont know if you remeber but I sold you an OS PET a number of years back (1999 or 2000). Nice collection, I am sure you have a few more in the last 5 years, eh?

Bruce, I had about 70 1/2A's in my collection (all different) at one time, and was JUST getting started.... They sure made a bunch! Between the Atwood's, Cox's, Anderson's, Holland's, etc and even if you just stayed with the North AMerican ones, you would have quite a pile when you were finished...

AJC

Dan Vincent

Bruce,

Thanks, they are not really all new. Excellent or better but I make my own display boxes liners so they can stacked and viewed with no dust collection. These are the same box layouts I used for the small engines from Arne Hende.

Andrew,

Sure I remember. You are one of the Motor Boys. Would you believe I finally came up with nine different versions of the OS Pet .09? That's counting RC carb versions too.

I still have more .049's to photograph...stay tuned.

rrragmanliam

My Feedback: (1)

Man I love seeing all this old stuff. Thanks for the pics and do keep them comming!

Rrragman

BMatthews

Make your own boxes eh? I like that idea. It's like you've framed them.

Dan Vincent

Thanks guys.

I have lots of engines left to photograph.

It takes time to dig them out but I'll get them all eventually.

XJet

It's interesting to note how close the carb is to the cylinder. I guess this makes the hole in the crankshaft as short as possible and therefore allows good crankcase compression to be maintained.

That got me to thinking -- why not mount the carb onto the front of the crankcase (as opposed to the crankshaft bushing) and use a suitably designed crank-web as a rotary valve?

Surely this would maintain the minimum amount of crankcase volume (thus providing a performance boost) while also providing the advantages/efficiencies of a rotary valve/drum without the friction/weight penalties normally associated with this type of induction system.

Any thoughts?

Japanman

That seems a go to me- One interesting thing though is that small crankcase volumes may be BAD! for tuned pipe equiped engines as the pipe tries to suck through the transfers- if there is only a small volume it is harder to draw extra gas from it.
But that said it seems that there is a trend towards this having a dimishing effect the smaller the engine. Also it is possible to open the inlet valve early to just let it suck through the carb.

J.M

mayfly

Dan, I'm new to this forum but it looks like you are the Atwood engine guy! I have an Atwood .049 outboard that I would like to find more info on. Do you have one?

Pond Skipper

Hi Mayfly not sure if you noticed Dan posted that back in 2004.
You can do a search for info on RCU also try RCG and CEF.

mayfly

Thanks for the reply Pond Skipper. I'm new to these forums, and trying to stumble my way thru them. Bear wi†h me...I'll find my way around eventually. I was just getting into RCG back around 2000? but priorities changed!

Pond Skipper

Here are insights on the .049 in general.

Pond Skipper

Mecoa sells spare parts and plugs:

https://www.mecoa.biz/shopdisplayproducts.asp?id=117





CRANKCASE, ATWOOD SHRIEK .049

Price: $8.50 Qty:


Part Number: 10-AS01
Old Part Number: REQUIRES ADDITIONAL TIME
Stock Status: REQUIRES ADDITIONAL TIME


CRANKCASE, ATWOOD SHRIEK .051

Price: $8.50 Qty:


Part Number: 10-AS02
Old Part Number: REQUIRES ADDITIONAL TIME
Stock Status: REQUIRES ADDITIONAL TIME


GLOW HEAD, ATWOOD SHRIEK .049

Price: $9.99 Qty:


Part Number: 11-AS01
Old Part Number:
Stock Status: Soon


HEAD ADAPTOR, ATWOOD .049

Price: $4.99 Qty:


Part Number: 11-AS02
Old Part Number: OUT OF STOCK
Stock Status: OUT OF STOCK


CRANKSHAFT, ATWOOD .049

Price: $9.20 Qty:


Part Number: 17-AS01
Old Part Number: REQUIRES ADDITIONAL TIME
Stock Status: REQUIRES ADDITIONAL TIME

PROP DRIVER, HOLLAND HORNET .049/.051

Price: $4.60 Qty:


Part Number: 20-1701
Old Part Number:
Stock Status: GOOD


PROP DRIVER, ATWOOD .049

Price: $3.25 Qty:


Part Number: 20-AS01
Old Part Number: REQUIRES ADDITIONAL TIME
Stock Status: REQUIRES ADDITIONAL TIME
more info

Atwood .049 .051 Back Cover

Price: $4.90 Qty:


Part Number: 21-AS01
Old Part Number: REQUIRES ADDITIONAL TIME
Stock Status: REQUIRES ADDITIONAL TIME


PROP WASHER, HOLLAND HORNET

Price: $0.90 Qty:


Part Number: 23-1701
Old Part Number: REQUIRES ADDITIONAL TIME
Stock Status: REQUIRES ADDITIONAL TIME
more info

SPINNER NUT, HOLLAND HORNET .049

Price: $6.99 Qty:


Part Number: 24-1701
Old Part Number:
Stock Status: GOOD
more info

PROP NUT, HOLLAND HORNET .049 / .051

Price: $0.90 Qty:


Part Number: 24-1702
Old Part Number: GOOD
Stock Status: GOOD


PROP NUT/WASHER, ATWOOD .049

Price: $1.25 Qty:


Part Number: 24-AS01
Old Part Number: REQUIRES ADDITIONAL TIME
Stock Status: REQUIRES ADDITIONAL TIME
more info

SCREW/NUTS, ATWOOD .049 BACKCOVER

Price: $1.70 Qty:


Part Number: 25-AS01
Old Part Number: REQUIRES ADDITIONAL TIME
Stock Status: REQUIRES ADDITIONAL TIME
more info

SCREWS/NUTS, ATWOOD .049 TANK

Price: $2.20 Qty:


Part Number: 25-AS02
Old Part Number:
Stock Status: REQUIRES ADDITIONAL TIME

HEAD GASKET, HOLLAND HORNET .049-.051

Price: $1.80 Qty:


Part Number: 29-1711
Old Part Number: OUT OF STOCK
Stock Status: OUT OF STOCK
more info

BACK COVER GASKET, HOLLAND HORNET

Price: $2.65 Qty:


Part Number: 29-1721
Old Part Number: REQUIRES ADDITIONAL TIME
Stock Status: REQUIRES ADDITIONAL TIME

GASKET SET, ATWOOD .049

Price: $4.55 Qty:


Part Number: 29-AS01
Old Part Number:
Stock Status: Good
more info

Back Cover Gasket, ATWOOD .049 .051

Price: $2.60 Qty:


Part Number: 29-AS21
Old Part Number:
Stock Status: REQUIRES ADDITIONAL TIME

TANK GASKET, ATWOOD .049

Price: $2.60 Qty:


Part Number: 29-AS61
Old Part Number:
Stock Status: REQUIRES ADDITIONAL TIME


PISTON/CYLINDER/CONROD ATWOOD .049

Price: $29.00 Qty:


Part Number: 33-AS01
Old Part Number: OUT OF STOCK
Stock Status: OUT OF STOCK
more info

TANK COMPLETE, ATWOOD .049 .051

Price: $23.80 Qty:


Part Number: 69-AS01
Old Part Number: 21-as02
Stock Status: Requires Additional Time

Atwood .049 Needle Spring

Price: $2.35 Qty:


Part Number: 83-as01
Old Part Number:
Stock Status: Good

SPRAYBAR, HOLLAND HORNET.049/.051

Price: $4.25 Qty:


Part Number: 84-1701
Old Part Number:
Stock Status: Good

SPRAYBAR, Atwood .049/.051

Price: $4.25 Qty:


Part Number: 84-AS01
Old Part Number:
Stock Status: GOOD
more info

NEEDLE VALVE & SPRING, HOLLAND HORNET

Price: $8.25 Qty:


Part Number: 85-1701
Old Part Number:
Stock Status: GOOD
more info

NEEDLE VALVE W/SPRING, ATWOOD.049

Price: $8.80 Qty:


Part Number: 85-AS01
Old Part Number:
Stock Status: Good
more info

NVA HOLLAND HORNET.049

Price: $12.35 Qty:


Part Number: 87-1701
Old Part Number: GOOD
Stock Status: GOOD
more info

Holland Hornet Engine Glow Plug Wrench - Fits Cox 049

Price: $4.99 Qty:


Part Number: 998-hh
Old Part Number:
Stock Status: GOOD

tflame

My Feedback: (1)

Hello
I bought 2 brand new Atwood shrieks from Mecoa when they were available I also have Atwood Wasp and I have an Atwood Signature series Green Head special engine. Here is a picture of the signature Atwood.049 green head.
Juan

tflame

My Feedback: (1)

Hello I have a few more Small engines of other brands in my collection. Here is another pic.
Juan

Dan Vincent

Pondskipper, I was looking at the MECOA Atwood parts for sale and noticed their Atwood tank assy. is actually an Atwood Wasp tank.

Only the Wasp had a brass pickup tube at the bottom of the tank. The Atwood’s simply had a hole on the upper left side where you stuffed in a fuel line for a friction fit.

Not to say the Wasp tank wouldn’t fit, it will fit an Atwood and an Atwood tank will fit a Wasp.

Too bad MECOA doesn’t sell the tank backplate separately, one of my Wasps has a hole in the center of the backplate because it was originally in a Wen-Mac Aeromite.

Prior to the Wen-Mac .049 being manufactured, the Wen-Mac Aeromite used Baby Spitfire .045, OK cub .049 & Wasp .049 engines, all modified for a one screw mounting in the Aeromite.

Bill Atwood designed the Atwood Wasp, Atwood and Wen-Mac .049 engines so some parts will interchange.