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Take Nothing for Granted on a new engine

Q

QuebecSierraGuy

Member
I am still in Phase one of my flight ...I have to put 40 hours on it because I did a combination of an 0-360 and the airflow performance injection system.

I have chased high chts and oil temps since the beginning.

The aircraft had a brand new Lycoming engine from Van's (Keep this in mind)

First I did a cowling mod....Cut my $950 cowl and made a huge exit area with a ramp and scoop. Then no change...just a little bit with the Oil temp.

Second I took out all of the baffels and re-did all of the baffels and sealed every hole possible to include the sammy James plenum.

Still nothing....high everything.

I did a recalibration all of the CHT probes
I removed all of the fuel lines, filters, injectors, etc and went through it with a fine tooth comb.

Still flew hot!!

After all of this ..............................................

Are you ready??????????????????????


Ready now??????????????????????


Timing!!!!!!!!!!!!!!!

The stupid Right Mag was so far advanced that it was behind. I had to physically remove the Mag and turn a couple of teeth.

First flight everything was back in the norm.

Take nothing for granted.

Sorry if there were any mistakes on this post...I am anxious to finish up and go to bed and not have to worry about what I am going to test tommorrow......or mess up for that matter.

Cheers
Bruce
 
Yes, and a factory-fresh IO-390 I know about came with the mags at, from memory, 15 or 18 degrees. Should have been 25.

Always go for the easy stuff first, eh?
 
Spark Advance

Never assume! I took my RV-4 with O-360-A1A to an approved shop to do the engine part of the annual inspection as I didn't have all the gear to do it myself. They checked the mag timing and adjusted one. For the following 12 months I was never happy with the smoothness of the engine, just off a bit. At the following annual we found the timing on one mag had been set at 20? BTDC vice 25? (parallel valve).

I have a new -390 in another project, the data plate states 20?BTDC, confirm the 25? in your message KPMarc?
 
It is 25 degrees

garnt.piper said:
Never assume! I took my RV-4 with O-360-A1A to an approved shop to do the engine part of the annual inspection as I didn't have all the gear to do it myself. They checked the mag timing and adjusted one. For the following 12 months I was never happy with the smoothness of the engine, just off a bit. At the following annual we found the timing on one mag had been set at 20? BTDC vice 25? (parallel valve).

I have a new -390 in another project, the data plate states 20?BTDC, confirm the 25? in your message KPMarc?
Click to expand...

Grant,
As far as I can tell from this Unison document

http://www.unisonindustries.com/docs/L-1318G_Text.pdf

All of the O-360 and O-320 engines are timed at 25 BTDC.

However, the lag angle on the impulse coupled magnetos does vary from model to model... so the magneto data plate may have a different number on it...

Can someone explain why the impulse coupler lag should differ from model to model while the basic timing is the same?... :confused:

The O-390 Lycoming is not listed in the Unison document...

gil in Tucson
 
Gil,

Sacramento Sky Ranch has a really nice write up on lag angle for the IC... it was an eye opener for me when I read it.. very interesting and worth reading.. (sorry, don't have the link handy now)
 
Timing

Thanks Gil, but I wasn't clear enough in my description. The dataplate on the engine 390 sump states 20?BTDC. I'll have a read of the IC info though, sounds useful.

Grant
 
Magneto lag angles

Radomir said:
Found the link:

http://www.sacskyranch.com/eng16.htm
Click to expand...

Thanks Radomir,

The comment on matching the magneto lag angle to the starter used was interesting.

As an example, my Tiger uses a magneto (4371) with a 20 degree lag angle and was shipped with a heavy Prestolite starter. Lycoming allows a faster turning SkyTec starter, and even ships replacement engines with them, but doesn't change the lag angle..... I wonder why not... :confused:

I believe Van ships his engines with a 4373 (25 degree lag) which would seem to be more suited to the faster turning small starters we use on the RVs...

The wonders of certified stuff....

However, it seems the 4373 Slick magneto is probably the best choice for our engines if we use the smaller, faster starters, whatever the Lycoming data sheet says.... :)

gil in Tucson
 
Update: Seems the factory IO-390 does indeed specify ignition timing as 20 deg BTDC.
 
IO...

KPmarc said:
Update: Seems the factory IO-390 does indeed specify ignition timing as 20 deg BTDC.
Click to expand...

Yes... I wasn't reading the "IO" bit... :)

It's interesting though, it seems that the 200HP IO-360 models can have either 20 BTDC or 25 BTDC, and yet have the same Lycoming model number.... :confused:

All of the 180 HP IO-360 models are 25 BTDC...


gil in Tucson
 
Lag Angle

It all comes together...? I've broken a Skytec from kickbak when starting, it spins the engine like a top. I've gone back to the original Lyc starter, but geez it makes hard work of it in comparison. On a cold morning the stars need to align to get it going. But, if I hand swing it it will go third flick when cold every time!

The -390 has the skytec on it now, and it whizzes over well also. I'm being very careful to prime well and try and avoid a kickback that may trash the starter. It has Slick mags also, so if they are set at 20?BTDC, and the Slick IC lag is 25?, I may be OK?
 
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