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Engine basics => Engine set up tips => Topic started by: Geoff Goodworth on September 07, 2007, 02:50:03 AM
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Ii have a few 40-size engines, all ABC/ABN except a newly acquired FP40 whixh has an iron piston.
Do the iron piston engines run differently—bettor or worse—to the ABC?ABN?
There is a fuel issue but as the FP is new and the price was such that I am still ahead of the price of a new LA if I replace the piston and cylinder liner, I am wondering about that option.
What do you guys think?
Cheers, Geoff
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They definitely run differently and respond to 'tuning" differently.
Quite a few guys in this area put a APC 11x4 on those, perhaps a head shim or two, and run them in a very nice wet 2cyc. mode. Quite effective for stunt in fact. Even using the stock mufflers. Don't use too large a venturi and no real need to block the boost port either.
Instead of shims, one might also hemi the head leaving the squish clearance at about .015-.016"
FWIW based upon my own re-work of both versions.
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Hi Capt. It has been our experience that the steel PC engines make more power. I found that filling the boost port was necessary. The engine "pop-corns" (miss-fires) without filling the boost. We use synthetic oil only as castor seems to interfere with combustion causing funny breaks and missfires that do not happen with pure ucon at about 18% with 10% nitro. The engine will easily swing an 11x6 but will run at any of the usual engine speeds associated with stunt. Our personal engines are still steel PC and have been running a long time. Good luck.
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Hi Dave:
Yes..I much prefer the older ones with the non-aluminum piston. I agree they seem to make more power.
I never tried to get one to run slow enough to use a 6 pitch prop--I know you like to run them there so would absolutely defer to your experience in that realm.
Are you folks going up to the Kilsdonk fly in Flint tommorrow? Hope to see you there.
Curt
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Big is planning to go. I'm up to some engine work. Dennis and Archie are working me to death.................
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I seem to remember that the cylinders on these steel piston O.S. motors were plated, (nickel?) even though they are steel motors.
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My steel pistion FPs run stock, my later model ones I modify the boost port on. Love em both. Though aside from the fuel consumption variations I am really liking my LA 46 better. Of course keep in mind I LOVE to run big diameter props, and the LA seems to be happy with that.
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Big is planning to go. I'm up to some engine work. Dennis and Archie are working me to death.................
Hey, whatcha doing haning around Stunt Hanger GET BACK TO WORK! VD~ LL~ HB~> HB~> mw~