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Old 06-27-2018, 04:25 PM
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DanH DanH is offline
Join Date: Oct 2005
Location: 08A
Posts: 8,141

Originally Posted by Lindyshambaugh View Post
Second was below spec fuel flow at full power of 17.5 GPH. The servo was sent back to AVStar and they adjusted the flow to 19.0.
Darn shame. 105 lbs per hour (17.5 GPH) is the correct spec (min fuel flow for rated HP). I lean mine in the climb from first power reduction. Airport is 200 feet MSL, and south Alabama can be as hot as anywhere.

Third were mag issues. The left mag was at 22 degrees BTDC (instead of 20) and the right mag was 30+ degrees. The internal timing on the right mag had to be adjusted. Now both are at 20 degrees
30 degrees will get it hot for sure. A dyno says 23 is a good all-around setting for a 390.

Since both the second and third things were done at the same time I'm sure the debate will rage on about which one solved the problem!!
No debate here.
Dan Horton
Barrett IO-390
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Old 06-27-2018, 08:20 PM
BillL BillL is offline
Join Date: Sep 2007
Location: Central IL
Posts: 4,727

Originally Posted by rvbuilder2002 View Post
Making mods before evening flying, or fully breaking in your engine is a waste of effort and cash.
As far as I am aware, RV-14's have been doing well with the standard baffle and cowl configuration in regards to temps.
The prototypes were both tested in temps just a couple degrees shy of 100F with a gross weight (at take-off) climb at Vy from 200 ft MSL to 10,000 on a standard temp laps rate day, without stopping. The CHT's topped out right around 400 and the oil temp topped out in the high 220's and then reversed in a downward trend midway through the climb (totally acceptable in those conditions for short duration flight).
Keep in mind this was at Vy (best rate) for the entire climb. Cruise climb at 120-130 Kts (makes sense in most situations since the ROC is reduced only slightly) and the temps will be noticeably lower.
What Scott has described here is a balanced heat rejection (therefore temps) for the engine and the oil paths. Since Vans has designed a pretty nicely balanced design for the inlets, a low CHT with high oil temperature balance would indicate that too much air is passing the engine side thus lowering the pressure on the top of the engine and lessening the air pressure for good oil cooling.

This would/will apply if the ignition timing is stock/correct.

Better cooling balance is a good item for the phase one investigation, but the high oil temps with short oil change periods should not be an immediate concern - at least not for temps reported.

1st Flight 1-27-18
Phase II 8-3-18
Repairman 11-15-18
Instrument Currency 12-17-18
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