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Gami Spread Check vs Busch's Red Box

Tcheairs

Well Known Member
Attempted a Gami spread check the other day trying to determine whether #4 is running leaner than the other cylinders, as the indicated temps would suggest. 190hp Titan XIO 360. 140 hrsTT..

Long story short I started at 10 gph (extremely ROP) and recorded temps (EGT CHT) and fuel flow in .5 gph segments all the way through peak and best LOP (7 gph). Was advised that the fuel flow changes were too wide and should have been done at .2gph increments. I was at 6500 msl and 24 square on the power. OAT was 54*

The point here is that I spent a lot of time in Mike Busch's "red box" which he believes is extremely unhealthy for the engine. I understand the theory of the "big pull" technique for leaning. Considering the required time for the temps to stabilize, I'm not inclined to go back up and put my motor in the red box in this lengthy procedure again .

My question is there no other way to determine whether or not there is an even fuel distribution by my Bendix injection system. I will certainly pull the nozzle to see if there is an obstruction.

I'd be grateful for comments
 
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Attempted a Gami spread check the other day trying to determine whether #4 is running leaner than the other cylinders, as the indicated temps would suggest. 190hp Titan XIO 360. 140 hrsTT..

Long story short I started at 10 gph (extremely ROP) and recorded temps (EGT CHT) and fuel flow in .5 gph segments all the way through peak and best LOP (7 gph). Was advised that the fuel flow changes were too wide and should have been done at .2gph increments. I was at 6500 msl and 24 square on the power. OAT was 54*

The point here is that I spent a lot of time in Mike Busch's "red box" which he believes is extremely unhealthy for the engine. I understand the theory of the "big pull" technique for leaning. Considering the required time for the temps to stabilize, I'm not inclined to go back up and put my motor in the red box in this lengthy procedure again .

My question is there no other way to determine whether or not there is an even fuel distribution by my Bendix injection system. I will certainly pull the nozzle to see if there is an obstruction.

I'd be grateful for comments

Perhaps go higher where there is no red box? What do you think percent wise you were making at 6500 and 24 inches?
 
ROP around 75%...I'm 75 years old and altitudes about 10K are pretty uncomfortable for me

That’s understandable.. potable O2 systems are pretty cheap.. another option is to take another pilot who can take the workload off you so that you aren’t tasked while at 10500 for the GAMI spread test..
 
What about running the check at a lower power setting..say 20 hg and 2350 rpm? Would the check still be valid
 
You could try to find when each cylinder peaks by starting lean of peak and enrichening. I would do this at the RPM/MP that you prefer to use for cruise.

==dave==
N102FM
 
And that would keep me out of the "red box"? Guess I wouldn't have to enrich all the way to peak power.
 
I can see now from a Mike Busch chart that 65/60 % power will keep me out of the "red box" thanks to all for the responses...
 
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