K&B Infant

ian1954 Sun Feb 15, 2015 3:43 pm

This is one of my scrap box engines that I have had for some time. It arrived siezed solid and I mean siezed solid.

I have soaked it, boiled it, heated it - unable to free it. We are talking soaking for months here!

The mounting plate at the back would spin round but it was impossible to remove the back plate despite the extraordinary special tool I made.

It was time for extreme heat (and yes, I do not recommend that you do this on the kitchen stove like I do). Heat applied with my little blowtorch with the engine on a heat brick.

I then let the solvents burn off, don my heat resistant gloves, apply special tools ..........

I forgot about the head removal tool - the old faithful

The rear mounting plate was loose because it had worn. It looked like the engine had been spinning on it!

Then shock, horror!

Finally dismantled and first stage cleaning

At least I can see what happened - the engine spun on the mounting plate, the plate wore and thinned, the backplate screwed further in and was worn by the crank pin - masses of swarf - seized engine.

All fixable - eventually!

rsv1cox Sun Feb 15, 2015 4:26 pm

Nice pictorial ian. I enjoyed it as I have been there before. It's amazing that these little gems can take that much punishment and still be fixable.

Mark Boesen Sun Feb 15, 2015 7:21 pm

Nicely done!

Oldenginerod Mon Feb 16, 2015 2:04 am

Ian.
The mounting plate is supposed to be able to turn. That's how they're made. The idea is that when you tighten the mounting screws it holds the backplate firmly against the firewall & stops the engine rotating. You can adjust the orientation of the cylinder. I know it sounds odd, but I've been through this myself. I certainly didn't have the issue with the backplate rubbing the crank pin though. I don't have an Infant, but the .035 Torp Jr. I'd dearly love to find a new glow plug insert for it.

Rod.

ian1954 Mon Feb 16, 2015 3:04 am

Oldenginerod wrote:Ian.
The mounting plate is supposed to be able to turn. That's how they're made. The idea is that when you tighten the mounting screws it holds the backplate firmly against the firewall & stops the engine rotating. You can adjust the orientation of the cylinder. I know it sounds odd, but I've been through this myself. I certainly didn't have the issue with the backplate rubbing the crank pin though. I don't have an Infant, but the .035 Torp Jr. I'd dearly love to find a new glow plug insert for it.

Rod.

That is useful to know - I will have do measure the plate and try and work out what could have happened with this one. As you can see from the picture the back plate encroached the crankshaft. I can only assume that as the engine spun - the mounting plate wore - the back plate tightened .........................

Oldenginerod Mon Feb 16, 2015 5:22 am

Ian.
All I can think is that a previous owner attempted to "tighten" the loose mounting plate by thinning or removing the backplate gasket. As I mentioned, I restored a Torp Jr. and those over on 049 Collectors gave me plenty of help with information and parts, including the info regarding the spinning mount. Two generous gents turned me up some prop drive washers (which was missing) and I was able to select the best one to give the least end float. It runs reasonably well except that it does want to quit when the battery is disconnected from the glow plug. Maybe I need to go with a little higher nitro. Someone handy with a lathe may be able to suitably modify a Merlin type insert to fit.
It may be worth checking your crank endfloat as that may explain the wear in the backplate, with the possible use of a starter.

Rod.

gcb Wed Feb 18, 2015 6:35 pm

Ian, is it possible that you have the .035 engine? I have never seen the .020 Infant without the tank on the bottom. Here's my Infant. BTW it originally came with an aluminum prop but I would suggest not actually running the engine with that prop.

George

GWILLIEFOX Wed Feb 18, 2015 6:57 pm

When K&B was getting close to putting the Infant on the market, they realized there weren't any props available for it! So they could get the engine on the market with a prop so it could actually be used, Lud came up with the aluminum prop.

706jim Wed Feb 18, 2015 8:35 pm

That's the first time I've seen the aluminum prop. Looks pretty crude.

I read somewhere that the AMA banned its use as it was unsafe.

Mark Boesen Wed Feb 18, 2015 10:27 pm

Yes, they did, but there were several companies making metal props, not just K&B, could you imagine what a metal prop could do to a finger on a healthy .60?

Lol, I do like the Infant prop: "No, I wanted a 4 inch pitch"...."Ok, give me a second, there!"

I wonder if that radial backplate could be used to rotate like a early helicopter or like the engine on the Wen-Mac Satellite:

c. 1959

Oldenginerod Thu Feb 19, 2015 3:23 am

Ian.
I think we may have been misled by the title of this thread. Although I can't get a good look at you engine by the pictures you posted, I think you may actually have a Torpedo .049 or .035 rather than an Infant, which was the .020. The .049 had a standard glow plug, wheras the .035 Torp. Jr. had a 5 fin "muff" retaining an insert type glow plug and the .020 Infant had a 6 fin muff also retaining an insert. Best I can see with yours is that it has 4 fins, but I can only find pictures of the .049 Torpedo with a plain unfinned head, so I'm not sure which you have.
As far as I know they all had a similar type fuel tank, but in many cases these were removed, possibly to reduce weight, and a remote tank used.

ian1954 Thu Feb 19, 2015 4:06 am

Oldenginerod wrote:Ian.
I think we may have been misled by the title of this thread. Although I can't get a good look at you engine by the pictures you posted, I think you may actually have a Torpedo .049 or .035 rather than an Infant, which was the .020. The .049 had a standard glow plug, wheras the .035 Torp. Jr. had a 5 fin "muff" retaining an insert type glow plug and the .020 Infant had a 6 fin muff also retaining an insert. Best I can see with yours is that it has 4 fins, but I can only find pictures of the .049 Torpedo with a plain unfinned head, so I'm not sure which you have.
As far as I know they all had a similar type fuel tank, but in many cases these were removed, possibly to reduce weight, and a remote tank used.

I have a pile of these engines - all being cleaned. Photos are deceiving. I have one of these with a tank somewhere. The one above is tapped for a tank.

I can see how these can get confusing but I will peruse my "scrap" box and see what I find. (All my grubby little engines in need of TLC are in my "scrap" box or should I say boxes!)

GWILLIEFOX Thu Feb 19, 2015 9:07 am

PAL is making an excellent little diesel version of the K&B Infant http://palmodelproducts.com/

Some time back, about 1998 they made a splendid Infant reproduction.

Tim Dannels has written the LUD Kading and the K&B Infant story in ECJ issue 114, 115, 116 and has a lot more good info on running, tuning, and restoring the little K&Bs in issues 175, 176, 177, and 178.

He is at WWW.Modelenginecollecting.com

ian1954 Fri Feb 20, 2015 3:18 pm

Thanks to all for the comments. I am thinking about a rebuild and dieselising it now.

It is a K&B Infant that has been butchered to take a glow plug.

Another for my project list!

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