# Lycoming O 320 questions

Discussion in 'Firewall Forward / Props / Fuel system' started by 4trade, Oct 20, 2013.

1. Nov 3, 2013

### Trackwelder

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When I was looking for an engine for my Buttercup, I found less than 20lbs difference between all of the Lycoming 4 cylinder engines, I was worried about weigh so I suck with building an Experimental 0 235 I have found that most parts are interchangeable between the 4 cylinders, Once you get past the case and the cylinders, I am using an 0 360 oil pump an unknown accessory case and an 0 235 C1 case,with ford 460 piston rings grooves redone to run 2 rings per groove, Gives me a Gapless ring for next to nothing. I have my doubts about the 2 magnetos in one setup, it seems to me that the safety factor of a dual ignition is lost, I have put in 2 Magnetoes one a 4100 series and the other a 4300 series, I am building this thing $100 at a time, ut with engine parts tha doesn't get me very far. 2. Nov 3, 2013 ### TFF ### TFF #### Well-Known Member Joined: Apr 28, 2010 Messages: 11,444 Likes Received: 3,182 Location: Memphis, TN Every A&P in the world laughs at duel mags, but as an A&P, you have to deal with what you are given. If I am building with no electrical and hand propping, Im a Bendix mag person. If I have an electrical system on a homebuilt, I would want to run P-Mags. 3. Nov 3, 2013 ### Dan Thomas ### Dan Thomas #### Well-Known Member Joined: Sep 18, 2008 Messages: 4,786 Likes Received: 2,017 Dual mags are on their way out. They were made by Bendix and used exclusively on Lycomings. Since Continental (TCM) bought Bendix, they see no reason to support Lycoming's magneto needs and so they've discontinued that mag and all the parts for it. Should be interesting in the next few years for the guys with those engines. Dan 4. Nov 4, 2013 ### kent Ashton ### kent Ashton #### Well-Known Member Joined: Aug 15, 2008 Messages: 717 Likes Received: 209 Location: Concord, NC The AD engines can be had fairly cheaply. If you don't want the dual mag setup you can use 2 Lightspeed Engineering electronic ignitions. It is also possible to modify them for a single mag and pair with an EI. Read of some RV builders doing that. I'm building an O-320-H2AD with two Lightspeeds. If you go that way, you have to block the oil passage to the magneto drive with a dummy shaft. 5. Nov 4, 2013 ### TFF ### TFF #### Well-Known Member Joined: Apr 28, 2010 Messages: 11,444 Likes Received: 3,182 Location: Memphis, TN Lycoming's problem is keeping what is certified going. My helicopters are certified with the duel mag no alternates are legal although the factory is looking for something, but they keep getting it wrong. 6 cylinder are more in trouble than the 4 cyl for right now as Continentals idea was slight Lycoming on the big 6 level. 6. Nov 4, 2013 ### Turd Ferguson ### Turd Ferguson #### Well-Known Member Joined: Mar 14, 2008 Messages: 4,675 Likes Received: 1,635 Location: Upper midwest in a house The solution is remove the dual mag, install a AC alternator in it's place, the alternator powers an electronic ignition. Lycoming has been flying this set up for a few yrs now. The dual mag engines will fly on for many years to come. The H2AD engines are actually sturdy engines, cylinders are bulletproof. 7. Nov 4, 2013 ### Pops ### Pops #### Well-Known Member Joined: Jan 1, 2013 Messages: 6,936 Likes Received: 5,849 Location: USA. I took a tour of the Lycoming factory a few years ago and they start with taking you to the museum. They had one of every engine but no H2AD. I ask why they didn't have a H2AD, the answer was, " We didn't make that engine". I have about 1500 hrs behind the H2AD and it would not be my first choice by a long shot. That is why the prices of the engines is lower and the Cessna's with the engines. Dan R. 8. Nov 4, 2013 ### Turd Ferguson ### Turd Ferguson #### Well-Known Member Joined: Mar 14, 2008 Messages: 4,675 Likes Received: 1,635 Location: Upper midwest in a house I have ~800h flying H2AD's plus an additional 1500h with an H2AD engine in a 172N that I owned. Very reliable. The latter eventually flew well past TBO. If it was the right engine for the application, I wouldn't hesitate to use one on a homebuilt. But I would follow what Kent is doing and replace the dual mag. Not because of reliability but because of parts scarcity. 9. Nov 4, 2013 ### Mark Schoening ### Mark Schoening #### Well-Known MemberHBA Supporter Joined: Aug 2, 2012 Messages: 97 Likes Received: 88 Location: KRHI Hi- .....I am using a Lycoming 0-320-E2D ..150 hp, 7.00:1 comp (car gas is good!) dual slick mags with dual impulse couplers, from a Cessna 172. accessory case on this engine is the lightest as there is NO provision for fuel pump (gravity feed) . I will use a 12 volt aux pump for takeoff and landing as problems have cropped up with cassutt acceleration and high climb angles causing fuel starvation. Stripped dry weight 245 lbs. No starter, no alt, no vac pump, and no ring gear (hand prop), so weight might be even a few lbs less. Using a 4 inch prop ext and a wood prop. If in the future if a starter is deemed necessary, a light-weight started and ring gear can be used with a battery mounted behind pilot for extra rear weight. Also a rear fuel tank can be used. Also I will consider a B&C 8 amp alt that bolts on the vacuum pad of lyc engines--using that setup as aux alt on my RV-9 --works well. Build on.............................. 10. Nov 4, 2013 ### 4trade ### 4trade #### Well-Known Member Joined: Nov 1, 2010 Messages: 527 Likes Received: 71 Location: Lahti/Finland Hi Mark! I have been thinking how much is high comp 160 hp engine compression....We have 98 octane autogas here, and that should be good enough for even older combustion chambers at 9.00:1 compression. Is there any other reason that most people use low comp engines on autogas than detonation? 98 should resist that detonation with higher compression easily. 11. Nov 4, 2013 ### Mark Schoening ### Mark Schoening #### Well-Known MemberHBA Supporter Joined: Aug 2, 2012 Messages: 97 Likes Received: 88 Location: KRHI Hi Vesa, 160 hp 0-320 usually has 8.5:1 compression ratio (H series may have 9:1 I think) In the States, 87 octane is "regular" gas, ( the cheap stuff) and is fine for 7:1 ratio. The "premium" here is 92 octane, good for 8.5:1 comp ratio. Be aware that the US octane rating is based on the AKI (anti-knock Index) and in Europe it is the RON index ..but all this means is that European 98 premium is the same as the US 92 premium and will work. I choose to keep 7:1 for the use of cheap gas over here. The argument against high octane car gas in the US is the vapor pressure. I am NOT qualified to discuss this, but I do I know I have operated lyc 320 with 7:1 on 87 octane at 10,00 feet or less, with no problems what so ever, and with no deposits on the plugs, and cleaner oil, I think it was better for the motor. I think by keeping the fuel cool to the carb, (think insulate fuel line in engine compartment,) vapor lock is eliminated. I think:whistle: Here in US 100LL is all that is available so even low compression planes use it. 100ll is$5.90 US and the "cheap" car gas is \$3.40...will keep my 7:1 compression..:gig:

Last edited: Nov 4, 2013
12. Nov 4, 2013

### Dan Thomas

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The real secret to avoiding vapor lock is to keep pressure on it. In the high-wing airplanes, gravity feed is often enough. In low-wing airplanes, pumps near the tanks are needed to push the fuel to the engine; an engine-mounted pump pulls on it and lowers the pressure on it, which lowers its boiling point, and vapor lock becomes much more likely. This reason alone is why it's more difficult to get Mogas STCs for low-wing airplanes. And it's the reason why older cars were so prone to it---the pump pulled the fuel from the tank and on hot days it would start boiling in the line. Cars now have tank-mounted pumps and the problem is nonexistent. Instead, we get to replace expensive pumps that are really hard and messy to get at.

Dan

13. Aug 17, 2015

### meallene

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You are a super guy in my book thank you for this link on Lycoming 320's...answered much for me...you have no idea ..thanks again ,ae

14. Aug 17, 2015

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