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The 80 psi leak down test will pinpoint a leaking valve.

Onex107 wrote:The 80 psi leak down test will pinpoint a leaking valve.

When I did the 80 psi leakdown test yesterday I had no air leaking through the valves, just the rings.

So....
High EGT can be caused by an excessively rich mixture. Fuel is still being burned when the exhaust valve is open. This scenario might also show lower CHT. But I am at a loss to explain why it would only be happening in one cylinder, and why it would just start randomly. Is the exhaust valve staying open longer than it should be? Maybe stuck slightly open?

BobDz wrote:So....
High EGT can be caused by an excessively rich mixture. Fuel is still being burned when the exhaust valve is open. This scenario might also show lower CHT. But I am at a loss to explain why it would only be happening in one cylinder, and why it would just start randomly. Is the exhaust valve staying open longer than it should be? Maybe stuck slightly open?

Bob,
When I enrichen the mixture the high EGT comes down, but the engine starts running poorly. So it seems the one cylinder is lean.

Bryan Cotton wrote:

BobDz wrote:So....
High EGT can be caused by an excessively rich mixture. Fuel is still being burned when the exhaust valve is open. This scenario might also show lower CHT. But I am at a loss to explain why it would only be happening in one cylinder, and why it would just start randomly. Is the exhaust valve staying open longer than it should be? Maybe stuck slightly open?

Bob,
When I enrichen the mixture the high EGT comes down, but the engine starts running poorly. So it seems the one cylinder is lean.

And your compression tests don't show a stuck / open valve.

BobDz wrote:And your compression tests don't show a stuck / open valve.

Correct

Just to link this to another relevant thread, check this out:
viewtopic.php?f=7&t=3725&p=58226#p58226

I may have caused the imbalance with my asymmetric introduction of fresh air.

When I did the cold air intake on the R2300 using a Rotec MKII carb, Rotec cautioned about elbos near the carb. There were none but but I did go ahead and make a flow straightener to dampen any intake air swirl. Perhaps something like this might be helpful.

I had considered that Brock but not sure how I would implement it given I don't have a flange mount. For now I'm going to remove my fresh air induction and verify the issue goes away. Then I'm going to add a second input to make it symmetrical. I'll fabricate a T or Y pipe to split the flow.

So I flew this morning with my cold air induction removed and I am able to climb to 4500' and keep it below 1400F. The other cylinders are around 1200F. I've lost some RPM in the climb with the loss of fresh air.

So this brings up an interesting thought - it seems I can steer the mixture left/right by messing with how the air goes into the filter, much like Michael (rizzz) observed in the other thread. What I need to do is to steer it the other way, and I can get my left and right aft cylinders in balance. That should allow a little more leaning overall and better performance. I am going to put another input into the air filter shroud, symmetrically, on the other side. I'll do some flight tests to figure out how to balance airflow between the two sides and achieve nirvana.

I also have a set of Great Plains intake manifolds that I bought from Graeme Smith, and I may try those to see if it balances fore/aft better than the stock manifolds. I did a quick check last week and it appears I will be able to bolt them on and get them to line up with the intake tube. These are the manifolds I have: https://www.greatplainsas.com/0251-/-bu ... ystem.aspx

For now I'm leaving it as is until after the eclipse.