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Convert Lycoming IO-360-A3B6D to IO-360-A3B6?


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More power with the advanced timing.  The cost is higher CHTs. So the answer can be, it all depends...

I'm a more power kind of guy. And controlling the heat can be done with a little extra effort...

Probably desirable for most MSers, maybe not all...

Best regards,

-a-

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8 hours ago, Rmag said:

As mentioned earlier, I had my A636D converted to to the A636 specification.  I just so happened to be looking at my data plate today while my right magneto was apart.  My plate is stamped 25° timing.

Is this because of my engine conversion?  Is 25° timing considered a desirable thing vs 20°?

The optional 20° of timing was not approved for the –D series engine.  

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  • 2 months later...
On 5/16/2017 at 5:30 PM, 201er said:

I did a trade in during factory reman for a a3b6 instead. Not only was it convenient but it was even cheaper as well. Another reason to get a core exchange factory engine now is to get the roller tappets on the cam as well. The mags are just half the story.

You mentioned it being cheaper? Any ballpark of the costs that you can share? Looking at a plane today where this will be a consideration.

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4 hours ago, smlynarczyk said:

You mentioned it being cheaper? Any ballpark of the costs that you can share? Looking at a plane today where this will be a consideration.

Ultimately it's a wash but initially it's cheaper. The factory reman A3B6 was about 2k cheaper than A3B6D. However, the A3B6 came with slick mags set to 20BTDC timing which runs cooler but robs you of power. So, I spent the money I saved on the core swap on the replacement of the Slicks with Bendix mags and returning timing to 25 degrees. 

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1 hour ago, 201er said:

Ultimately it's a wash but initially it's cheaper. The factory reman A3B6 was about 2k cheaper than A3B6D. However, the A3B6 came with slick mags set to 20BTDC timing which runs cooler but robs you of power. So, I spent the money I saved on the core swap on the replacement of the Slicks with Bendix mags and returning timing to 25 degrees. 

Thanks for the info!

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the A3B6 is k$2-3 cheaper than the A3B6D.

But there will be some associated cost like different hoses and brackets making it overall a wash.

25 degrees robs you of power in theory but I am not sure by how much and if it is worth it (how many knots in cruise ???) 

 

 

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7 minutes ago, OR75 said:

the A3B6 is k$2-3 cheaper than the A3B6D.

But there will be some associated cost like different hoses and brackets making it overall a wash.

25 degrees robs you of power in theory but I am not sure by how much and if it is worth it (how many knots in cruise ???) 

25 gives more power. 20 reduces power to improve cooling. One of the tricks Mooney used to turn an F into a 201 was upping the timing from 20 to 25 by going with the A3B6D! It's a noticeable difference. About 5kts. 

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5 hours ago, 201er said:

25 gives more power. 20 reduces power to improve cooling. One of the tricks Mooney used to turn an F into a 201 was upping the timing from 20 to 25 by going with the A3B6D! It's a noticeable difference. About 5kts. 

That could explain my lower TAS... I have Slicks with 20 deg on the A3B6. It would be nice to be able to go to the 25 deg timing. 

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On 7/26/2017 at 2:56 PM, wishboneash said:

That could explain my lower TAS... I have Slicks with 20 deg on the A3B6. It would be nice to be able to go to the 25 deg timing. 

Or buy one of those new fangled electronic ignition doohickeys.  They automatically advance the timing based on MP and RPM.  Keep one of the mags you have, and put the electronic system in place of the other.

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2 hours ago, Bob - S50 said:

Or buy one of those new fangled electronic ignition doohickeys.  They automatically advance the timing based on MP and RPM.  Keep one of the mags you have, and put the electronic system in place of the other.

As someone with an A3B6 and one of those new fangled electronic ignition doohickeys  I would rather have the 25 deg timing I think.  

So my usual altitude of flying is between 7 and 10k.  The ignition advances to basically 24-25 degrees at altitude.  As a result I don't think I truly see the benefit of better mpg.  Once I get a few of my cooling issues worked out I may experiment with 25deg timing to see what if any difference I get. 

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