CHT and timing

[meyer228]

Just did an EFIS/EMS upgrade and discovered my CHT's were a little hot (417F - #3). My previous EMS would only monitor one cylinder at a time so I usually monitored #3 and it would occasionally go above 200C on climb out. So checking and considering the usual suspects. Full rich , intake leaks, timing, baffles, exit opening, air dam...

Mixture is full rich but my timing was +3.5 on the left mag...

Does any one know or have a guess regarding the effects of timing on CHT?

We've set both mags to 25. Going to go fly it Friday and report back.

RV6a, CS, o320-D1A w/ported heads

[Mike S]

Originally Posted by meyer228

Mixture is full rich but my timing was +3.5 on the left mag...

Does any one know or have a guess regarding the effects of timing on CHT?

We've set both mags to 25.

+ 3.5 above the 25, for a total of 28.5?

Too much advance will raise CHT, too little will raise EGT. Has to do with where the fuel/air charge is doing its burning.

[meyer228]

Originally Posted by Mike S

+ 3.5 above the 25, for a total of 28.5?

Too much advance will raise CHT, too little will raise EGT. Has to do with where the fuel/air charge is doing its burning.

28.5

Yes, I understand that. Just wondering if anyone has had experience in how much it would raise the CHT's.

[Mike S]

You might try reading through this thread, should help with your questions.

http://www.vansairforce.com/communit...d.php?t=132119

[meyer228]

Originally Posted by Mike S

You might try reading through this thread, should help with your questions.

http://www.vansairforce.com/communit...d.php?t=132119

thanks! I searched around and didn't find this post. I'll still post my results...

[n82rb]

I dialed mine back about 3 degrees and got about 30 degrees drop.

Bob burns
Rv-4 n82rb

[Jesse]

I found a Mag with a +6 degree advance. Dialing it back to suggested timing dropped by CHT's at least 30 degrees F.

[meyer228]

Originally Posted by n82rb

I dialed mine back about 3 degrees and got about 30 degrees drop.

Bob burns
Rv-4 n82rb

That's what I am hoping for.

[meyer228]

Originally Posted by Jesse

I found a Mag with a +6 degree advance. Dialing it back to suggested timing dropped by CHT's at least 30 degrees F.

30 degrees will put me in the 380 range. I'd be happy with that.

[GalinHdz]

Besides CHT temperatures, what advantage or disadvantage will dropping the timing a few degrees do with an electronic (dual Pmags in my case) ignition?