55 or 53 pitch to fly the trench?

[Elkslayer]

As a young buck it is hard to do, but I must set aside my pride and ask advice from the wise and seasoned 170 pilots.

I am purchasing a 1C172 EM7653 prop from a fellow member and am toying with the idea of re-pitching it to 55. I have a 7845 and 28 inch goodyears on my A model right now but will be putting it on 6.00's and switching the prop for the long cruise to Idaho this spring. It will be nice to have a climb and cruise prop to switch out for long trips but I need advice as to whether I should pay $250 to re-pitch the new prop or not. I plan on flying the trench and don't know if 55 will get me much more speed than the 53 or if it will be worth it operating out of the strips along the way and through the mountains. Reading some of the threads it sounds like the shorter climb with the 53 evens out the speed gain with the 55.

Any advice, opinions, or theories are greatly appreciated

[hilltop170]

I have flown the trench four times in my 170A with an EM7655 flying back and forth to Alaska. It works just fine at gross weight using about 1000' for takeoff at standard conditions, indicating 105mph at 2450rpm leaned to 7.2gph. If it was me, and I had a 7653 I would put it on the plane and fly it to see how it compares with my numbers. I bet you won't see a lot of difference but I have never flown a 7653.

[blueldr]

I don't think a trip from Alaska to idaho using a 53 0r 55 inch prop is anything to worry over. If I had an airworthy 53 I sure in hell wouldn't spend $250 for a 55 repitch just for that trip. I've flown the trench, which is really no different than any other flying, in a stock engine '52 B with a 53 and it did just fine.
I've also flown all over the Idaho back country on the same airplane and prop without any problems. Just understand I was not contracted to haul lead ingots either.

[edbooth]

My 53 B had a 53 pitch prop on it which I flew for about 12 years. Before the Yellowknife convention, I had it re pitched to 55. I noticed that I picked up about 3-4 MPH, but took just a little more pavement taking off. I didn't have or use any calibrated instrumentation to verify performance, but I could tell the difference. I have flown long distances with another Assoc. member that runs the 56 pitch "California prop" that seemed to be popular back in the 70-80's, and at altitude With what appears to be the same power settings, I walk away from him after a while......go figure I have kept the 55 pitch and have flown all over the U.S. Including high altitude strips and high mountain passes with no problems. It's kinda like driving an old 36 HP Volkswagen, just need to plan your movements.

[marathonrunner]

I have flown both the trench and the tracks. I sort of like the track route better. Prince George to Smithers to Dease Lake to Whitehorse. Plenty of fuel stops and places to motel or camp. I think the tracks is shorter a bit too

[Elkslayer]

Thanks for the quick feedback gentlemen, you guys bring up good points and I think I"ll go with Rich and just put the prop on as it is. As soon as I get her home to Idaho I'll be putting the big tires and climb prop back on to go explore the back country anyway.

I might look into the re-pitch down the road if I find a sale as I'm buying the second prop for a fast cruise for future long point to point flights.

[GAHorn]

I have flown the trench four times in my 170A with an EM7655 flying back and forth to Alaska. It works just fine at gross weight using about 1000' for takeoff at standard conditions, indicating 105mph at 2450rpm leaned to 7.2gph. If it was me, and I had a 7653 I would put it on the plane and fly it to see how it compares with my numbers. I bet you won't see a lot of difference but I have never flown a 7653.

It's important to know one's actual weight when making comparisons like this.
I have a '53 170-B using an EM7655 and at 2,000 lbs, 2450 rpm it trues out exactly at 105 knots at 7500 ft., burning 7.8 on average. ( I don't have an EGT and lean IAW Owner's Manual method and RPM indications.)