Starter springs coming loose

With reed-valve engines.. there should be ample clearance for the spring to hook-around the boss on the case at the base of the cylinder.. whether you install the spring first.. or last. The "back-end" is not meant to clamp the wire.

Please excuse these grimy examples..

Cam-style



Zero-drag



They've always stayed in position for me once installed. I can't speak for repro-springs. Mine are genuine Cox parts.. and fit tightly. I will add that I only wind-them "one-turn". Any more than one turn is unnecessary.. and will distort the spring.. as well as risking a deeper-cut to your finger; should you slip.

I've used electric-starters in conjunction with a Tee Dee-style aluminum spinner. It's VERY important to place a few drops of light-oil behind the prop drive-plate and flip the prop a few times to work it in.. before connecting the glow-plug. Go easy with an electric starter. Use "light-pressure" and "short-bursts". This will greatly reduce heat build-up from friction.

I second to what Roddie said, do not wind the spring over 1 or max 1.25 turns. For electric starter use you may want to put a stainless steel washer between the prop drive plate and the crankcase to reduce abrasion. Bernie sells them in different sizes.

Ok guys you have picked up on one of my bad habits. I tend to pull the prop back through as many turns as the spring will allow before I release it. Could be what's happened here.

I've found that about 3 quarters of a turn is enough for the cam style.

I've also noticed that some repro springs (again cam style) are a bit loose and the radius of the coil is just a little too big for the hook to catch the cam "first time, every time". Not sure whose manufacture they are, maybe they are Estes or something, but anyway different compared to the few genuine oem springs from the '80s that I have.

A few used engines, that I have received, have had the spring would up tight around the crankcase neck, clearly a sign of "winding it up too tight".

I also have an early BW with the colour worn off the neck, it had the original "wound too tight" spring on it which I replaced. I personally think that signs of use add charm to a runner

I don't think I have ever had a spring come loose off the cylinder base though I'll need to check mine for that too. Maybe you can improve that situation by pre-forming that part of the spring into a tighter radius?

probably the most authentic source on how to use the spring starter: an excerpt from the COX leaflet "Bob and Jack start their COX Thimble-Drome Plane":

KariFS wrote:I've found that about 3 quarters of a turn is enough for the cam style.

I've also noticed that some repro springs (again cam style) are a bit loose and the radius of the coil is just a little too big for the hook to catch the cam "first time, every time". Not sure whose manufacture they are, maybe they are Estes or something, but anyway different compared to the few genuine oem springs from the '80s that I have.

A few used engines, that I have received, have had the spring would up tight around the crankcase neck, clearly a sign of "winding it up too tight".

I also have an early BW with the colour worn off the neck, it had the original "wound too tight" spring on it which I replaced. I personally think that signs of use add charm to a runner

I don't think I have ever had a spring come loose off the cylinder base though I'll need to check mine for that too. Maybe you can improve that situation by pre-forming that part of the spring into a tighter radius?

If I remember correctly, the spring starter was invented by Mr. Davis of DDD. He sold the first ones to Cox, then I believe he sold the rights to Cox.

I removed some starters from my engines early on. I figured if I can't hand-start it I have a problem (bull-headed perhaps?). I finally accepted them.

George