O-540 lycoming vs O-470 continental

[bestbearhawk1231]

Hi Guys and Gals, I have a lead on a "wrecked" Cessna 310 for a very good price and is equipped with the continental o-470 engines. I know that in the experimental world, Lycoming seems to be king... is there any specific reasons for that? I don't have much experience with either so any pros vs cons would be appreciated before I drop a load of cash on this bird. I know that Continental was having trouble with its jugs blowing their tops for a while and Lycoming has issues with cams. Is there anything else I should be aware of? I am not sure of the exact version of the engines so they could be the 235hp or the 260hp version. The plane is currently owned by an elderly A&P mechanic who bought it from the insurance company when the previous owner decided to do a little "offroading" with it when he arrived at the end of the runway and realized that there was no taxi way parallel to the runway. The pilot was attempting to turn around and dropped the nose wheel in a gopher hole which buckled the nose gear and caused a prop strike. The current owner performed a prop strike inspection on the engines and the cranks run out good. The engines currently have around 200 hours on them and the plane has set for several years in the hanger.

Sooo, is there any reason not to use the 470 on a bearhawk and what should I be aware of with the continental? Is it simply a case of ford vs chevy? I am not looking to build a fire breathing dragon with hot rod parts, simply looking for the performance of a 6 cyl on take off at high density altitudes. Currently living in western NE and most places I would like to go in the future are up hill from here.

Thanks for the help.
Joe

[Chris In Milwaukee]

I can't think of a reason not to use one. Aside from it being a bit heavier than a Lyc-540, C-180/182 owners seem to adore them, and there looks to be some favorable upgrades for them. Certainly worth keeping in mind. I have access to an O-470 myself for a good price, should I choose to use it.

I seem to recall there are a few 470 Bearhawks out there. I don't recall what installation gotchas there are with them, however. Mark does sell an engine mount for it.

~Chris

[whee]

I think it's a Ford/Chevy thing. The two builders with 470s that I talked to were very happy with them.

I haven't a clue why Lycs rule the experimental world but I wouldn't pick an engine only because it was easily available. It is the hart of your airplane so pick the engine that meets your requirements and then start shopping.

I dug deep when picking my engine; made lots of phone calls, read many TCDS and overhaul manuals, etc. My research lead me to believe that a fully dressed O470 (no prop) was 23 lbs heavier than a parallel valve O540. Put angle valve cylinders on the 540 and the weight is a wash between the two engines. Prop selection will effect the FWF weight significantly.

If I ever decide I need more power I'll likely end up with a big bore Continental.

A word of caution; Continentals have through hardened cranks so they are somewhat brittle. Dialing the crank isn't enough to determine the crank (or cases) are good. The crank needs to me removed and fully inspected (dye pen, ndt, maybe even ultrasonic). If the seller won't guarantee the crank than I would walk away.

[Bcone1381]

I think what Whee said is probably in line with Continental's service manuals directions regarding prop strike. I would be surprised if they allow the engine to be returned to service without a detailed inspection of various internal parts including the crank. Sellers of prop stuck engines alway declare the out of round value. I don't believe that plays a factor into deciding whether the engine will be torn down for an inspection. The Collapsed nose gear with the engine running at idle were enough to mandate that inspection. Don't be too experimental.

[Battson]

Each seems to have some advantages and disadvantages.
I am no expert, but I know about differences like the dry vs. wet cam, mag placement, starter interface, cylinder reliability, frequency of ADs, ability to shock cool or not, etc. I won't spell it all out here.
When I did my research, people in my circles thought the Lycoming had a better reliability record (mostly around the cylinders) - but it's just opinion and circumstancial evidence, I've never seen any hard statistics. I am sure the manufacturers work hard to keep it that way.

[jaredyates]

Weight and size seem to be some of the main differences. There are lots of different variants, but in some cases the 470 ends up weighing more than a 540. The 470 can require adjustments to the firewall to clear the accessories.

[Battson]

Weight and size seem to be some of the main differences. There are lots of different variants, but in some cases the 470 ends up weighing more than a 540. The 470 can require adjustments to the firewall to clear the accessories.

Good points Jared - and you've jogged my memory.
Some models of the 470 have protrusions at the top of the engine (air intake? I dunno). But friend of mine has told me his 470 won't fit under the cowl without a custom raised firewall and instrument panel. Either that, or you have to install a blister. Of course this is no problem if you are scratch-building.

[Mark Moyle]

There was a long discussion about this on the old yahoo group. What wasn't ever fully nailed down were the fully dressed weights of the Lycoming parallel/angle valve and the 470-520's. My interpretation of fully dressed is absolutely everything installed, ready to start. I spoke with many people..those who do the O-470/520 to the O-520's. each gave me numbers similar to Bob Barrows Lycoming weight of 400#. The numbers were 413 to 430#.... if I remember correctly. Firewall clearance is an issue if you don't know which models will fit. An IO520 will fit with enough firewall clearance to move the prop flange back to 54-1/4" ahead of the datum. It is a tight fit...and a chore to adjust the throttle body and injection pump....but doable. I'm using the induction system from the IO520D. Total weight, exhaust manifolds, oil cooler, full size alternator and starter, bendix 1200 series mags ready to start less engine oil is 461 pounds. I do have the light weight starter and alternator... and can reduce the weight further with an electronic ignition system. The system is more complex than the carbureted system.. I will say it's been an adventure figuring out how to make the continental fit....and deciding what niceties I'll need to omit due to the extra engine weight.. but the question still remains.. what does the fully dressed parallel valve O-540 weigh?

[Bcone1381]

Tell us about your engine cowl.

[Mark Moyle]

Mooney Acclaim...eBay $574. Got it from a guy who worked at the manufacturing plant. Needs additional carbon fiber added to fit. Firewall is the same width as the distance/outer dimension of the bottom tube at the panel. I am going to make another engine mount to move the engine ahead another 1-1/4". Prop flange will be 55-1/2" ahead of the datum line. When I started this project The Bob had changed the specs for the prop flange ahead of the datum line to 56-1/2". Built this thing pushing engine back as far as possible. Now the Bob has changed the prop distance ahead of the datum line back to 58-1/2". I'm hoping this'll weigh under 1,450 pounds... might make it there with an MT prop? And yes MG....get my Pacer done... getting there...hand surgery after breaking both have set me back a few months.

[whee]

I don't like it when Moyle starts talking weights and engine location. Makes me wish I'd stuck with my big bore Continental idea. I think I'll fly to AK just to go for a ride.

[Mark Moyle]

Don't know if you'll want to wait that long to experience Alaska. Bought my Pacer to become a proficient tail wheel pilot. Before finishing the Bearhawk. Busted landing gear...decided to repair the Pacer..that decision was made 3-1/2 years ago...and at one point the Bearhawk was closer to completion than the Pacer. my plans number is 938..... what plans number are we up to?

[Bdflies]

My first build was powered by a Continental IO-520D. The installation probably added 18 months to the build. Maybe more. Mark's engine looks clean and new. Mine was salvaged, with most components sent out for 'yellow tag' or bought to tailor the install. An item that was neither new or overhaulled, was the starter drive. Sure enough, inside a hundred hours, it started a downward spiral to failure. Swapping mine for an overhaulled unit was pretty easy, because I had -just-enough- clearance to squeeze it out and back in. I'm not saying to design a mount, for that specific event, but if you don't have room to remove the drive, ya gotta pull the engine off the mount to change it. Just imagine how much fun that would be.

I flew that Continental a bit more than 600 hours. I've flown Lycomings more than twice that. My impression is that the Continental was more 'finicky' and less robust than the Lycomings. I had leaky cylinder-head joints, leaky pushrod tubes, failed valve guides, etc.. It ran well and was powerful. Never gave me a reason not to trust it. I was, however, always wondering what the next fix would be. When taken care of and not abused, Lycomings seem to just run and run.. My $.02

Bill

[Mark Moyle]

My build is a combination of two engines. IO520BA small journal var crank, ECi nickel ceramic bore. Cylinders continental 1994 cast date. No AD's. 339 hours on a new crank/overhaul including the angle drive, cam and lifters. Case was cracked....got a good deal. The second engine was a TSIO520WB 1394 hours since new. Came out of a medivac Barron in Boston six hours shy of TBO. Used the Barron case, crank and rods, all measured at new dimensions. Punched in new guides, ground the seats three angle, I have a pile of 520 cylinders and valves... ground the valves and picked the best. Replaced the bearings, new ECI 8.5-1 pistons and rings. Used ECi's renew kit for the cylinders... they measured at new minimum diameter. Gami injectors, new 1200 series bendix mags, shower of sparks....counter weight arrangement with the prop...no rpm restrictions. Can limp along lean of peak with this engine. I'm into the engine and prop less than $22k. prop was fist run 600 hours remaining....sent in for overhaul. Did some other stuff like port matching and smoothing of exhaust and intake runners... a few tricks I picked up from Dick Flynn racing.... a Winston cup head guy.

[Erbman]

My understanding of why Lycomings seem to be more popular than Continentals in Experimentals has mostly to do with marketing. Lycoming has long marketed to the homebuilt market, with offerings in the O-235, O-320, O-360 (all 4 cylinder), and O-540 (6 cylinder) class. Continental's offerings were limited to O-200 (4 cylinder) or O-470 and O-520 (6 cylinder). If you needed a 4 cylinder engine in the 150-200 HP class Lycoming was pretty much your only option. Meanwhile, Continental seemed more interested in putting engines in Cessnas and Cirruses. This may have changed a little recently, but seemed to be true in the past.

[Mark Goldberg]

Hey Russ. You are correct in your comments. Continental was not really interested in working with homebuilders like Lycoming was. Meaning they did not give good discounts for OEM type customers like kit manufacturers, and also required a core charge which Lycoming doesn't for kit manufacturers. Seems to me that they lost a lot of market/sales because of this attitude. But what do I know. Mark

[Chris In Milwaukee]

Certainly seems like a missed opportunity, doesn't it? Thankfully there are a lot C-182s and others out there from which to harvest a usable engine. But yeah, they could have probably done a lot more.