carusoam Posted May 24, 2017 Report Share Posted May 24, 2017 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- Quote Link to comment Share on other sites More sharing options...
jetdriven Posted May 24, 2017 Report Share Posted May 24, 2017 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. Quote Link to comment Share on other sites More sharing options...
smlynarczyk Posted July 26, 2017 Report Share Posted July 26, 2017 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. Quote Link to comment Share on other sites More sharing options...
201er Posted July 26, 2017 Report Share Posted July 26, 2017 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. 1 Quote Link to comment Share on other sites More sharing options...
smlynarczyk Posted July 26, 2017 Report Share Posted July 26, 2017 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! Quote Link to comment Share on other sites More sharing options...
OR75 Posted July 26, 2017 Report Share Posted July 26, 2017 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 ???) Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted July 26, 2017 Report Share Posted July 26, 2017 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. Which Bendix mags did you get? Quote Link to comment Share on other sites More sharing options...
201er Posted July 26, 2017 Report Share Posted July 26, 2017 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. Quote Link to comment Share on other sites More sharing options...
wishboneash Posted July 26, 2017 Report Share Posted July 26, 2017 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. Quote Link to comment Share on other sites More sharing options...
jetdriven Posted July 26, 2017 Report Share Posted July 26, 2017 it is easy to do. Change the left mag to the approved part number, reset the timing, make a log entry. 1 Quote Link to comment Share on other sites More sharing options...
OR75 Posted July 26, 2017 Report Share Posted July 26, 2017 5 minutes ago, jetdriven said: it is easy to do. Change the left mag to the approved part number, reset the timing, make a log entry. can you reference the Lyc. SB ? Quote Link to comment Share on other sites More sharing options...
jetdriven Posted July 26, 2017 Report Share Posted July 26, 2017 15 minutes ago, OR75 said: can you reference the Lyc. SB ? SI1325C. its optional, and I opted out. https://mooneyspace.com/topic/3877-io-360-a1a-what-mag-timing-20-or-25-deg-btdc/ Quote Link to comment Share on other sites More sharing options...
OR75 Posted July 27, 2017 Report Share Posted July 27, 2017 SI-1325A is to go from 25 to 20 degrees not sure it describes how to go from 20 to 25 i cannot find an SI-1325C Quote Link to comment Share on other sites More sharing options...
jetdriven Posted July 27, 2017 Report Share Posted July 27, 2017 (edited) that's it. It's an optional service instruction. So undo it if you wish. Edited July 27, 2017 by jetdriven Quote Link to comment Share on other sites More sharing options...
Bob - S50 Posted July 27, 2017 Report Share Posted July 27, 2017 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. Quote Link to comment Share on other sites More sharing options...
mccdeuce Posted July 28, 2017 Report Share Posted July 28, 2017 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. Quote Link to comment Share on other sites More sharing options...
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