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Culver Cadet Section => Culver General Discussion => Topic started by: Bghotrods on March 18, 2012, 09:51:14 PM

Title: 4AC-199 Franklin Engine Barn find
Post by: Bghotrods on March 18, 2012, 09:51:14 PM
Hello all, I am new to this group and thank you for allowing me to be a member. Recently I had the opportunity to pick an old barn that has been in a family for over 100 years. During this adventure I came across a Franklin aircraft engine 4AC-199 with the prop still attached. Being in the automotive restoration business for the past 35 years this item caught my attention and I knew it had to be rescued. It has dual mags. I wired the engine up in an attempt to fire it up on the stand it came on. I removed the prop. With the plugs out the motor turns over freely. I put the plugs back in, attached the mag wires to a kill switch, wired in a starter button and plumbed in a pulse fuel pump.  With a fully charged battery and all good connections the engine turns over about 1/4 turn before acting like it's kicking back. And the starter bendix disengages. Several attempts more and the engine caught and fired up.I only ran it for a moment and shut it down. It acts like it has too much timing at start up.. Or the starter has an issue.. My question is.. Do the mags require some type of retard at start up? Not very familiar with these engines.. Any help would be appreciated! Thanks Ben
Title: Re: 4AC-199 Franklin Engine Barn find
Post by: Bill Poynter on March 18, 2012, 11:14:23 PM
My guess is that you have one mag with an impulse coupling and one without.  With that configuration, you would normally start the engine on the one with the impulse coupling.  In addition to giving a hotter spark, the coupling also retards the ignition at cranking speeds.  You would switch to both mags after the engine starts.
Title: Re: 4AC-199 Franklin Engine Barn find
Post by: Bghotrods on March 19, 2012, 11:16:28 AM
Hi Bill, thank you for replying. Is there any way to tell which mag is which? They both only have one wire coming off of them and they look identical. They are Eiseman aircraft mags, model number AM 4, right side is serial number P22693P and the left side is P36057P and both have the same symbols numbers and letters of RFJHDE25. Each cylinder has 2 spark plugs, one mag I'll assume fires one set of plugs on each cyl and the other mag fires the other set of plugs on each cylinder. If I were to wire 2 separate kill switches one to each mag, shut off one of the mags then try and start the engine do you think this would help? And if so is there any way of finding out which mag to turn off? Not sure if this is the way to proceed or not as I'm really not that familiar with this engine combination.. Put a 1700 HP blown alcohol engine in front of me and I can tune that! LOL! Thanks again. BEN
Title: Re: 4AC-199 Franklin Engine Barn find
Post by: JoeB on March 19, 2012, 12:32:00 PM
Hi Ben,
The engine should not 'kick back' when cranking.  It seems that the timing is not set correctly or you have a magneto problem (possibly a disengaged impulse coupling?). 
Do you hear a 'snapping' sound when you rotate the engine over, and is it consistent with rotation?
The magneto timing should be checked/confirmed.  If you want to try starting the engine on just the left mag, and then again with the right to compare that would help too (without requiring any tools).
My Cadet has a Franklin 4AC-199 and I use both mags when starting, the engine cranks over smoothly and starts quickly (usually in a blade or two).
Now you know this question is coming...what are your long term plans with this engine?
Best regards,
Title: Re: 4AC-199 Franklin Engine Barn find
Post by: Bghotrods on March 19, 2012, 02:52:00 PM
Hi Joe, yes there is a snapping that is consistent with the engine turning over. What is the best way to check the timing? And what should it be at? Not at all sure where or how to time it.. Don't have a book on it yet. Short term is to droll all over it.. But it is going to be for sale! Thanks. BEN
Title: Re: 4AC-199 Franklin Engine Barn find
Post by: Paul Rule on March 19, 2012, 10:39:16 PM
From my 4AC199 manual & Parts book:  Reference the marks on the prop flange to the centerline of the case... there should be a top center and a 28 deg BTC mark.  The magneto points should open (fire) at the 28 BTC mark.  Be sure the impulse coupling(s) have 'clicked' then back up just enough to get to the 28 BTC mark.   Best to use a vibrator timing light but a 0.001" shim (or cigrette paper) as a feeler gage will work if you are carefull.

If you hear 2 destinct 'clicks' when you pull through then you have an impulse coupling on each mag.  If you hear only one, you may have 2 perfectly timed mags, or you may have 2 impulse couplings and one is stuck or has a broken spring. You may also have have only one impulse but I doubt that... 2 are standard. If you have a broken spring (and you have mounted 2 separate kill switches) try running on one mag at a time...the bad mag will have a much higher RPM drop.

90 HP  at 2500 RPM max.  7:1 comp ratio.  4.25 " bore.  3.5" stroke.  Oil press.- 35-45 psi.   240 deg. MAX oil temp.

Title: Re: 4AC-199 Franklin Engine Barn find
Post by: Dan C on March 20, 2012, 12:00:42 PM
Be careful starting up any engine that had been idle for years. What had been a viable engine can be turned into a pile of scuffed, scorched steel in a few moments.
Title: Re: 4AC-199 Franklin Engine Barn find
Post by: Bghotrods on March 20, 2012, 01:29:23 PM
Hi Paul, Thanks for the awesome input! After removing the mag covers we have determined that both impulse couplings are firing at the TDC mark on the prop flange the markings are UDC And a line with an "I" on the other side of the line. Assuming UDC is under top dead ctr. There is a nut on the sides of the mags.. I'll assume that I need to loosen the nuts and rotate the mags till they both fire at 28 deg before TDC then back the prop off slightly to 28 deg and set the point gap as suggested earlier.
If that sounds about correct I'll continue on and try to re-fire it. Thanks Again Ben
Title: Re: 4AC-199 Franklin Engine Barn find
Post by: Bghotrods on March 20, 2012, 03:05:44 PM
Hey there Paul, well it took a few minutes for it to sink in but I believe I have it now.. Both mags are firing at the same time.. Looks like they both click at just about 8 deg before TDC. I backed off the prop to 28 deg BTC and the points both have the required .001 clearance as read in your previous post. All that said I'm still where I started. I pulled the starter and bench tested it., bendix and starter are working as designed. I'm going to start it again on one mag then turn the other one on and vise versa to see if that makes a difference. Do you know off hand what kind if fuel pressure the pump requires? Will a new style electric one work on this engine? And what type of oil do these run?
Again thanks to everyone for all your help, couldn't do this without your support! BEN
Title: Re: 4AC-199 Franklin Engine Barn find
Post by: JoeB on March 20, 2012, 11:16:04 PM
Hi Ben,
The tags on my magnetos are a bit 'antiqued', it would take a bit more effort to read than I was expecting!
Your question about fuel pressure, the Culver uses a gravity fed system so pressure is most likely not an issue (no fuel pump).
Uh oh, the oil topic...I think you may have just started the dreaded 'oil' thread on the Culver forum! (I just changed mine with Phillips 66 X/C 20W50)
Title: Re: 4AC-199 Franklin Engine Barn find
Post by: Brett Lovett on March 20, 2012, 11:41:07 PM

The impulse coupling or couplings are what both make the snap, and retard the timing when the prop is turned slowly forward.  They disengage when the engine is running at idle or higher.  In checking the timing of the mags you want to move the prop CAREFULLY forward just past the point where you hear the click (and remember the engine may immediately start or kick back when you hear the click regardless of anything else unless you have the spark plugs removed).  Then turn the propeller backwards to get to the 28 degree mark where the points should close (or open when the prop is moved forward).  If you turn too far back then the impulse will re-engage and change the timing indication.

The idea of the impulse is to both produce a hot spark when the engine is turning slowly (starting) and to make the plug fire later than normal, closer to TDC in order to avoid kicking back.

Title: Re: 4AC-199 Franklin Engine Barn find
Post by: Bghotrods on March 21, 2012, 11:01:37 AM
Wow what awesome help! Well we re-fired the engine after checking the timing and point settings on both mags. We cleaned up an original bendix scintiua type ED ignition switch we found when we got the engine and wired it to a panel on the engine stand along with a mechanical sun oil pressure gauge. The switch has positions for ( off, right,left,and both) I fired the engine on the left side position first and it started once it got fuel and ran very smooth and responsive, I switched to the right side position and the engine RPM increased a couple 100 RPMS, switching back to the left the RPM decreased by the same, switching to both there was a slight raise in RPM and the engine ran awesome. Shutting down the engine and re-starting it a couple of more times on the right mag it took right off. Oil pressure maintained 40+lbs. I may have the starter looked at by a guy I know that works on vintage starters to be sure the bendix is performing properly as it is still disengaging I think to early. Again thank you to all for your great support and to an awesome group of entheuists!