Gents,

Here's my latest resto project, a Webra 2.5 Mach I. As you can see from the before pic, this was a "nothing to lose" subject, so I am very pleased with the outcome.

Randy, Looks great. Have you run it? If you have run it what were your impressions. Jack

Looks very nice, Randy -

If it's not a secret, would you like to tell us what went into the restoration? Did you simmer it in a crock pot with antifreeze? Bearing replacement? New head & needle valve or did you make 'em?

In your sig line, what does BO all my own M's mean?

Tnx - Lee

OK,
Well, the case was in terrible shape with the holes drilled oversize and allot of tool nicks. I carefully reamed the holes to cleanup with a tapered reamer then turned tapered pins to fit. These were then sweated into the case with Alumaloy and the case was shaped and preped for finishing. There is a pic of the 3 main castings masked up ready to go into the blaster. I did that job at work where we keep a blast cabinet ready with very fine glass bead, the finished engine pic gives evidence of the quality of the finish. Afterward, the case was machined and the transformation was complete. The muff fins were carefully straightened and the ragged edges turned off. It was then polished and sent to a friend in Oz for anodizing. The spinner nut is for an ED Racer, but came on this engine.

The crank was cleaned up and I had to take a light truing cut off the pin and fit a new rod. The original was shot. It also required a new rotor drive pin be made and fitted.

This is a ball bearing engine so the bearings were replaced. The rod was made new as was the NVA and prop washer. The rotor was wallowed and loose so the rear cover and mating face of the rotor were resurfaced and a new center pin made and the whole thing refitted, The drive hole in the rotor was was also bored and bushed because it was so sloppy. The 8 cheesehead screws were buggered, so I carefully hammered the heads back into shape by drilling a hole just the size of the thread major diameter in a block of steel and inserting the screws for support. After they were reshaped a light facing cut was taken to freshen them up and they were treated with cold gun bluing. The tommy bar was straightened and cleaned up and treated the same as the screws.

I have not run it yet, but I made a new contra-piston and oil hardened the piston and the compression is like new, so I have no doubts it'll run just fine.

I forgot, another great gun product I use allot in restorations is blue and rust remover. Its very mild but will clean up the discoloration of rust in most cases.

Builder Of all my own Models: BOM

Wow, Ryan - there's a whole lot more to it than I thought! Thanks for the explanation.

If you still feel like talking about this, how did you locate the new holes in the case for the cheesehead screws?

Why do they call them "cheesehead"?

Was the dacing cut along the major diam of the threads? Why do they call it "dacing"?

Tnx - Lee

Hi Lee,

A couple things. First "dacing", my error, facing cut, I have corrected the text. The cut was across the face of the head to remove the hammer marks.

Cheesehead screws are called that because the head looks like a wheel of cheese, believe it or not.

I got the hole location from a good engine and then just redrilled them on the mill.

Marvelous, absolutely marvelous!

I have just in the past year returned to playing around with small engines and metal working. My goal is to eventually build a running diesel but along the way to hone my skills I have been rebuilding old engines and making new replacement parts but haven't yet gotten to the stage where I could manage such a nice job as you have done with this engine.

My next project is to convert an old Webra 3.5CC marine engine to a non-marine engine. It will require some cooling fin work as well as the manufacture of a new venturi and needle valve assembly and prop driver. I have been following some of your postings on some of your projects, bookmarked them and have made notes of interesting ideas/techinques that you have noted.

Thanks for sharing.

cheers, Graham in Embrun near Ottawa Canada.

Graham,

Thanks so much for your kind words. There's allot of satisfaction in doing something like this for me. Its relaxing and fulfilling at the same time. And even while I am not in the business, putting value back into what is essentially junk isn't all bad either. Please show us some of your work too, nothing like motorhead talk with pictures!

As I mentioned over on SSW, that is an EXCELLENT restoration.

From an old discussion on this forum, some had "cheese head" screws and some came with hex screws. I bought mine in mid-late fifties and it has the hex screws. There was a small wrench (long gone) in the box if I remember correctly.

In any case, I took some pics of them in case someone has that version. I have no idea of which was used first.

George

Thanks George,

I believe the hex heads predate the slotted screws though I really don't know either. As I received pictures during my research it seems to me the earlier Mach I's used the hex heads, but the number of subjects I had to compare was small. It should also be mentioned that there were very early ones, the first of the series I believe, that had red anodized cylinder muffs instead of green.

Anyway, if anyone has one with the hex head screws DON"T replace them, they are probably original. In fact is anyone has one with the hex heads and they'd like to part with it, let me know, I'd like to have that example as well, and condition is not and issue!

What is "SSW" ?

Curious, the old 3.5cc webra marine engine I mentioned earlier has these hex head bolts. I am guessing that this engine is from the early 60's, I haven't taken the time to pin it down any closer than that

cheers, Graham

http://www.clstunt.com/cgi-bin/dcforum/dcboard.cgi

Graham,

SSW is Stuka Stunt Works, probably the most active CL Forum around. Try the link above.

I think your engine more likely dates in the '50s. Post a picture and we can find out pretty quickly.

SSW - Stuka Stunt Works - I already knew that - just didn't make the connection. I regularily read through a lot of posts on SSW but don't post much.

I will try and post a picture of the old engine in the next couple of days.

cheers, Graham

I believe there was a Mk-1 with a green muff that had more and finer fins and was more of a tapered shape, larger at the top, of course. This was somewhere just prior to the Mk-2, I believe.

I also think I remember the plain bearing version 2.5cc having a red muff. Perhaps they used those in the early Mk-1's. Just a guess, not even sure if the bore was the same.

These are memories of a young teen with his nose almost against the engine display case at my LHS in the nineteen fifties, so they may be a bit inaccurate.

George

[quote]ORIGINAL: RRyan

Thanks George,

I believe the hex heads predate the slotted screws though I really don't know either. As I received pictures during my research it seems to me the earlier Mach I's used the hex heads, but the number of subjects I had to compare was small. It should also be mentioned that there were very early ones, the first of the series I believe, that had red anodized cylinder muffs instead of green.

Hi Randy,
The Sept 1954 Aerom has Warring's test of the 1st model Mach 1 Diesel, released in 1953. It has green fins and cheesehead screws. It would seem that the red fin engine was released sometime in 1954.
regards
David Owen

Hello RRyan

As mentioned in one of the above letters the outside shape of the cooling fins were a bit different - in a later version.

The one you have is the original one.

Even earlier the backplate was different - and had a 2-piece NV assembly.

The hexagonal bolts for assembly were used in the 60's.

My own MACH 1 is from -55 and still running very fast - which was a trademark of the MACH 1.

Later there came a glowversion which was less succesfull than the diesel.

Use this fuel - and it will run : 30 % castor + 35 % kerosene + 34 & ether + 1 % amylnitrit or -nitrate.
Put on a wellbalanced light prop f. ex. a 8 x 4 Tornado plasicote woodpropeller and you will enjoy !!

My complments for your work.

KR

hld - OY-9901

Thank you Hans, for the information and the compliment.

randy

i have found a webra like that but with a mariene head and throttled iwould like to know how did you make the cooling finns of the head i always have troublemakeing them

laurence

Hello Laurence,

I did not make the head, I cleaned of all the damaged areas and had it anodized. Cutting fins can be a pain, but with practice, especially at learning how to shape and sharpen a cutoff tool. it gets easier. Most people grind the tool with WAY too much clearance (the angle from the cutting edge down) and the tool vibrates and dives. You want a very shallow angle so that the tool can only feed solwly and if you feed too fast it will actually stop cutting. I don't have time right now, but later I take a picture of some of my tools so you can see what I mean.

Randy,

Have you run it yet?

George

HI George,

Nope, haven't run it yet but have no doubt it'll be just fine.

Another Mach 1 brought back to serviceability. My thanks to Jon Fletcher for his excellent work.