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IO540 narrowdeck vs widedeck

airguy

airguy

Unrepentant fanboy
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Calling the gray hair engine builders here...

Would any of you be concerned flying a (properly) overhauled IO540 narrowdeck versus a newer wide deck? My intention is to keep standard compression on it, this is not going to be a "run it like you stole it" engine. I acquired a midtime core (narrowdeck) and was thinking of putting new cylinders on it and go through the bottom end for my RV10, but I'm getting some widely differing opinions on the sanity of that approach. To be clear - the engine will be overhauled - not just dusted off and installed.

I know parts are getting harder to find, and more expensive. I'm wondering if I'm doing the equivalent of installing a G430W in this case, at the end of its useful service life.
 
I have a ND engine to overhaul, and many of the mainstream builders here have/will provide overhauls on ND engines. Talk to Barrett - if they're hopping up engines for more HP, they actually prefer a ND engine, I believe. Look at all the ADs coming out on newer 1990/2000s era engine components, might ease your mind on the older stuff. I asked an engine builder at Sun N Fun about my ND components and any concerns - they shrugged and said 'There's nothin wrong with what you have.'
 
Nothing bad about a narrow deck. A mid time one is definitely worth overhauling, especially with new cylinders.
Don't let the "experts" convince you otherwise.
 
airguy said:
Calling the gray hair engine builders here...

Would any of you be concerned flying a (properly) overhauled IO540 narrowdeck versus a newer wide deck? My intention is to keep standard compression on it, this is not going to be a "run it like you stole it" engine. I acquired a midtime core (narrowdeck) and was thinking of putting new cylinders on it and go through the bottom end for my RV10, but I'm getting some widely differing opinions on the sanity of that approach. To be clear - the engine will be overhauled - not just dusted off and installed.

I know parts are getting harder to find, and more expensive. I'm wondering if I'm doing the equivalent of installing a G430W in this case, at the end of its useful service life.
Click to expand...

Not sure what is getting harder to find or more expensive. The major difference is the case (which you'll have) and the cylinders, which are still plenty available on the new market.

I've got a narrow deck in my -10 and other than minor mods to the baffles, there's no practical difference between it and a wide deck.
 
Kyle Boatright said:
Not sure what is getting harder to find or more expensive. The major difference is the case (which you'll have) and the cylinders, which are still plenty available on the new market.
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I'm going with new cylinders - these are a mix of steel and chrome at only 1000 hours - says something about the way it was operated maybe. No propstrike but no logs either - so full teardown, not cutting corners. According to the widow it has 1000 hours first-run.

The steel cylinders are, I believe, identical to the ones on my IO360 so I'll keep those for a future rebuild and sell the chromes. I want to go back with new cylinders ported and polished, standard compression.

With those comments, I guess I'm in the market for an engine rebuild guy within a couple flight hours of MAF that would look over my shoulder and make sure I'm doing it right. I really do want to learn how to do this, I'm a 30-year engineer and gearhead but have never cracked a Lycoming case and don't mind paying a guy to show me the tricks. I've got lots of time on my side - probably 3 years before I need the engine, it can be done now and pickled or done later and installed.
 
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If you want to go with a wide deck Barrett engines would probably pay quite well for a first run narrow deck case. They prefer them and are looking for them. You could then pick up a wide deck case.
 
Me too

Barrett IRANed my narrow deck IO540 with slightly higher compression and new cylinders. They stated at the time that they preferred narrow deck. I was very happy with the results. Good luck with your local searching!
 
I believe (again, not the engine expert here) that the cylinder flange area on the cases are a little heavier on the ND engines. Less potential of cracking versus a WD which cracking in this area is quite common. Lycon had quite the stat at one point on cracking of WD cases vs ND cases. The early ND engines had issues with losing cylinders at the bases, but was fixed with hold down plates to reinforce.

My ND was pulled from an abandoned Aztec, all components yellow tag/OH'd by the Tulsa groups (sourced some that didn't from CO Air Parts).
 
Difficult to find cases

I had a difficult time finding a case when a crack was discovered in my ND O-360. Lycoming doesn’t manufacture ND cases so at some point you may have the same issue.
 
Tommy123 said:
Nothing bad about a narrow deck. A mid time one is definitely worth overhauling, especially with new cylinders.
Don't let the "experts" convince you otherwise.
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+1

The 320 in my 6 and hte 540 in my 10 are both ND cases. IMHO, there is nothing deficient about the design and therefore no reason pass on one. The key differences with the ND are the thinner cyl base flange (though they have a thick clamping plate) and the captive through studs. I believe it is EXTREMELY uncommon for a cyl base flange to break and the WD through stud arrangement is just as prone to problems, if not more so than the ND style.
 
iwannarv said:
I believe (again, not the engine expert here) that the cylinder flange area on the cases are a little heavier on the ND engines. Less potential of cracking versus a WD which cracking in this area is quite common. Lycon had quite the stat at one point on cracking of WD cases vs ND cases. The early ND engines had issues with losing cylinders at the bases, but was fixed with hold down plates to reinforce.

.
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I can't speak to early teething issues before the clamping plates were added, but do not believe that is a current issue. Barret is a pretty well respected shop with a lot of experience. Have pretty good confidence that they would not prefer ND cases and cylinders over WD if that type of problem still existed. That said, one MUST follow the guidelines for maintaining clearance when installing the plates and torquing the bolts. If you don't insure a good clearance and let the plate nestle into the flange radius area, it will lose torque over time and THAT WILL likely cause flange cracking. On some designs they have a slightly different plate for one of the cylinders, IIRC. So watch for that.
 
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I talked to my neighbor that overhauls engines. He said there is nothing wrong with a narrow deck, and he doesn't experience any more part issues with them than the wide decks.

He did say if it is a really early narrow deck, the cylinders might not have the reinforcement plates at the base, and those early cylinders can be an issue. I see you said you're going with new cylinders, so that shouldn't be an issue.
 
Barrett

I had a discussion with the late Monty Barrett in the early to mid 90's. He preferred the ND case for the 540's but we did not discuss any other details. In those days the aerobatic engines were 250 hp engines pumped up to over 300.
He also told me the aerobatic engines run hard would start to lose oil pressure at around 800 hours because of bearing wear. That was based on most of the flying done at full power. 10-1 pistons.
 
msires said:
I talked to my neighbor that overhauls engines. He said there is nothing wrong with a narrow deck, and he doesn't experience any more part issues with them than the wide decks.

He did say if it is a really early narrow deck, the cylinders might not have the reinforcement plates at the base, and those early cylinders can be an issue. I see you said you're going with new cylinders, so that shouldn't be an issue.
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The hold down plates do not come with the new cylinders. Though I doubt there are many engines out there that do not have them, excluding the low compression variants (7.5:1) that still do not use them. If your engine doesn't have them, you will also need longer through bolts to accomodate them IIRC.
 
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