Surging

[dekky111]

RV-7A with an O-360 and a constant speed prop. Got grief. Was running rich causing engine to "load up" @ full power--cured by leaning. Sent the carb off for a Service Bulletin rebuild on the floats. Now at full power, the engine surges rhythmically. Not cured by leaning. Fuel flow is 17.4 gph @ full power. CHT's/EGT's all normal. Engine runs smooth @ 23/23 or 24/24, just a full power problem.

Any clues? I'm tired of looking for alternate landing spots with every take-off (good exercise, though).

Jack
24 hours
N811AK

[scard]

First questions:
Which prop governor?
What ignitions?
Happens every single time or does it seem to be more pronounced in certain conditions (hot, cold)?

[airguy]

Not gonna say for sure it's NOT the engine, but I'd be looking REAL hard at the prop governor. What model is it?

[N941WR]

Originally Posted by scard

What ignitions?

Does it do this when running the left, right and/or both ignitions?
Easy test and if it is the same on the left, right, and both, it is probably not the ignition.

If it changes, you have just found your problem.

Good luck.

[N908RV]

Jack,

If you have the Jihostroj governor - consider that as a potential culprit. Many surge at full power, particularly on cold days. Check the old threads for info on this.

Rob

[dekky111]

Governor is MT with a Hartzell blended airfoil prop. Does this on mag, elec ign, or both.

E-mailed MT today and got a response. They have a problem with the blended airfoil prop and their model B prop governor. They have agreed to a rebuild upgrade to model F.

I'll let you know if it works

Jack

[scard]

Originally Posted by dekky111

Governor is MT with a Hartzell blended airfoil prop. Does this on mag, elec ign, or both.

E-mailed MT today and got a response. They have a problem with the blended airfoil prop and their model B prop governor. They have agreed to a rebuild upgrade to model F.

I'll let you know if it works

Jack

That will probably do the trick. They have problems with the "B" model in general. I had one that surged too. Had the "F" revisions done, it got a little better, then I bought a PCU5000X and have been very happy ever since.

[dekky111]

Originally Posted by scard

That will probably do the trick. They have problems with the "B" model in general. I had one that surged too. Had the "F" revisions done, it got a little better, then I bought a PCU5000X and have been very happy ever since.

Scott,
I'll hope the F revision works. If not, the PCU5000X will be the choice. Who makes it? Where is it available?

Jack

[kiwipete]

I had the same problem and sent the Gov back to MT. Once it was updated to F mod it 's been fine.
If you do a search you'll find quite a few others have had the same problem.

Peter

[David-aviator]

Originally Posted by dekky111

Scott,
I'll hope the F revision works. If not, the PCU5000X will be the choice. Who makes it? Where is it available?

Jack

Check this thread....

http://www.vansairforce.com/communit...d.php?p=207532