Cold break in.
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1/2A Airplane Engines 049-074
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TOPIC: Cold break in.

Cold break in. 11 years, 6 months ago #105

  • pfinn
Hello
I just purchased the Big Mig .074 CL. I've read about the cold break in with 1/4 tsp "Oil". Would that be just oil (Castor or other) or just the fuel mix? Can't wait to recieve my engine. It will be going into a Brodak 1/2a Pathfinder, which I am also waiting for!

Thanks
Phil

Re: Cold break in. 11 years, 6 months ago #106

  • victor
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It is castor oil. All instructions are in the top menu (Support)

Re: Cold break in. 11 years, 6 months ago #107

  • pfinn
Thanks Victor. Read through those. Very informative and helpful. I'll post some after I get my engine.

Phil
Last Edit: 11 years, 6 months ago by . Reason: misspell

Re: Cold break in. 11 years, 6 months ago #116

  • RknRusty
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I followed that procedure with my Big Mig .061 CL. It helps limber up the tight TDC pinch a little bit. But it can still be a pain to get it cranked the first time. I had to use a lot of head shims to finally get mine to crank. I actually put a Cox Babe Bee head on it with 5 shims and it finally cooperated. After that first break-in run, I went back to the Norvel head and it was a lot more cooperative. I highly recommend a starter spring if it's available for your engine. Mine cranks on the first flip every time with the spring now. It really takes a lot of fuel through it before it limbers up nicely, and you'll be flying it while it finishes loosening up. The more you fly it, the better it'll run. I really wore my prop finger out the first couple of days fiddling with it. It's an awesome runner now, scary fast with an APC 5.5x2 prop. I fly it with a Master Airscrew 5.5x3. Those APCs are impressive on the test bench, but the MA gives you some serious pull in the air.
Last Edit: 11 years, 6 months ago by RknRusty.

Re: Cold break in. 11 years, 6 months ago #118

  • pfinn
Thanks for the tips RknRusty. I actually just did the cold break in today after work. I picked up some SIG Castor this past weekend. Still waiting for some appropriate fuel. Way too much car fuel out here where I live. It seems to be all synthetic. I did notice though that some of the 15% nitro as well as some of the 20% nitro had about 17% oil (synthetic) only. If I were to add another 10-15% Castor to the mix, would this be OK. I see that a 20% oil mix is needed.Or is this pushing it for break in purposes? This engine is for a Brodak 1/2a Pathfinder kit I recently ordered from my semi-local hobby shop. They will be also recieving a new batch of correct fuel very soon as well as there is a big local CL event happening (Circle Burners in Southern CA). I guess I'll just have to be patient.

Re: Cold break in. 11 years, 6 months ago #119

  • RknRusty
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pfinn wrote:
If I were to add another 10-15% Castor to the mix, would this be OK. I see that a 20% oil mix is needed.Or is this pushing it for break in purposes?
Most people agree that any castor/synthetic mix should be half castor, which would make it hard to get right.

My favorite fuel is Glowplugboy Rocket 24. It has 24% nitro/17% castor. I add 1.3 ounces of castor to bring it up to 20%. Here is a link.
www.gcbmrc.com/GlowPlugBoy_prices.htm
Scroll down the page to "Rocket 24 All Castor." He'll mix any combination you want if you buy either 2 or 4 quarts, I forget which. Shipping usually only takes 2 or 3 days to me.

He also sells on eBay if you search for Glowplugboy. His pictures are confusing, but the descriptions are accurate. He's a pretty good guy from my experience.

Lots of people at rcgroups.com swear by Sig Champion fuels, but I've found it to run less smooth and I've also blamed it for fouling plugs. Everyone else loves the stuff.

Here's a fuel mixture spreadsheet. Just plug in your volumes and percentages and it will tell you how much castor to add.
www.coxengines.ca/files/castor.xls
Last Edit: 11 years, 6 months ago by RknRusty.
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