If the end of a piece of copper tubing is crushed in a drill chuck, you can make a constriction of whatever size you want depending on how much the tube is crushed. The photo is of 1/8" od tubing that was used to dampen under cowl pressure
measurements for cooling investigations by inserting it into the sensing tubing. The constriction would be most effective if placed between the intake manifold and the chamber (fuel filter).
It is hard to imagine that the change in MAP in the range of 26.7 to 27.1 would in itself cause a hiccup unless a significant mixture or timing change is associated with it. An examination of the controller maps might shed some light on this.
The instances of sag that I have encountered have not been hiccups but a sudden transition to new steady state condition of reduced but smooth power. For me, recovery from sag did not happen without some sort of operator intervention.
FWIW
Steve Boese
RV6A, 1986 13B NA, RD1A, EC2
From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of Bill Bradburry [bbradburry@bellsouth.net]
Sent: Thursday, September 06, 2012 7:21 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Intermittent hiccup
Do you think that I could have an intake leak that is causing this fluctuation? This makes no sense to me. How could it be fluctuating??
Bill B
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Bill Bradburry
Sent: Thursday, September 06, 2012 12:11 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Intermittent hiccup
I noticed that the manifold pressure was fluctuating between 26.7 and 27.1 during cruise today and I was getting some hiccups.
Did you block both ends of the filter or just one end? I don’t think I have a drill bit smaller than 1/16. What did you use to drill
the holes?
Bill B