The International Cessna^® 170 Association

Hi all,
After all the back and forth with the cracked crankcase and repairing, etc, I ended up getting another engine from a Swift in Virginia - zero time, pickled for a few years. That was in April. I just yesterday got around to firing it up, which it did- Yea! At first it wasn't showing me any oil pressure, but then I primed it and voila, away it went. One concern I do have is that it runs a bit rough, especially on the Left only mag. It does better on the Right only, which is about the sae as both. The timing was done two weeks ago by the shop mechanics. I used my mags on the new engine, and they were working beautifully on the old engine. when I did the runup on the old engine it was consistent, constant and powerful. I haven't run it enough yet to do a compression check, but I don't know what connection there would be between the two, just sayin'.
Today I went back out, pulled the plugs and investigated. Nr. 6 bottom was fouled, as was Nr. 1 top (number right? both at the back of the engine). Nr. 3 had some minor sludge going on, but nothing terrible. All others were still new. After replacing them, same thing, no change. I will pull the plugs again on Tuesday to see if they are the same.
I'm a bit worried....Any advice? Thank you!

spduffee wrote:... Nr. 6 bottom was fouled, as was Nr. 1 top (number right? both at the back of the engine). ...

No, I think you mean cylinder number 1 and cylinder number 2.This drawing comes from the TCM O-300 Owners Manual and shows how the Slick magneto wires should be installed. The manual also has a diagram for the Bendix magnetos which show that they are "clocked" differently.

Usually engines out of service or new engines are oil primed before they are started after having been dormant. Possibly you did that but had to prime the line to the oil gauge. What was done to the engine to prepare it for its return to service ? Desiccant plugs removed and then you had new plugs installed.

Gary, yes, you're right. I wrote this on the fly after a frustrating day. I should have checked before I wrote. It was Nr 2 bottom and Nr 1 top.
Jim, the engine came in from Virginia. I removed the fuel pump (it came from a Swift), removed all of its accessories, replaced them with mine and all new gaskets, mounted the engine, hooked up the hoses, etc, and installed new plugs. The timing was done by the shop here in Auburn. Added mineral oil, cranked the engine without the top plugs to build pressure, which didn't show up. I then replaced the plugs and fired it up IAW the 170 POH. After seeing no pressure buildup after 20 sec. I shut it down. I repeated the same, with the same results then decided to prime the engine through the oil pressure indicator line and the two plugs at the front of the engine. After that the oil pressure indicated 30, then rested at a higher 45, which I understand can and must be adjusted down to the 30-ish range. As I mentioned, it was properly pickled until it was shipped to me. Its logbook says it's a zero-time after rebuild. What else should I have done to prepare it?

First, I would not be worried at this point. These are the normal things that have to get worked out when installing and breaking in a new engine.

Second, hold on to that fuel pump and I'd the one way valve that might have been in the plumbing as those are required on a '48 and many are missing. They are hard to come by.

Third, you can not adjust the oil pressure. The valve under in the accessory case of this and other small Continentals is a high pressure blow off and will only open when the engine is cold and the oil thick. At normal operating temperatures and pressures it is full closed. It should not be confused with a Lycoming engine which does have adjustable oil pressure.

Priming of the oil pump when new as you had to do is not uncommon.

As Bruce mentioned don't worry about your oil px, check timing , plugs and wires as first step. I'm hoping its just preservation oil if they were not cleaned well before starting

Well, the young Mechanic at the shop had an idea - let's remove the P-lead and see what happens. It worked! Apparently he just did that on a 310 late last week and it did the trick. I checked both mags and there was no roughness, no RPM drop on either side. The engine still isn't as smooth as I would wish, but it's getting there. The plugs I pulled today were better, with the exception of #1 - top and bottom this time. We checked the leads but the aparatus is so old na dbeat up that we don't trust the results. That's on the menu for tomorrow.

Arghhh...one step closer....yes. Its been a long, long road. I was just thinking of Langholz' posting about airplanes flying overhead when your bird is own being pretty annoying. My house is right in the flightpath down the valley and I swear there's a plane a minute flying by at 1500' and it's painful. Soon, soon...

Oil pressure up to 55 psi is the standard allowable now (due to improved lifters as of about 30 years ago, was the statement of the TCM Field Rep/, Cory Thompson.) A new (blue painted) oil press relief spring is also part of the deal.

Updates for any interested bodies: Jim Musgrove, who flies a 170-A also, is parked just a few hundred yards from me in Auburn. I owe Jim A LOT for all the help he has selfishlessly provided. The ignition switch was giving us strange readings, in the off position, so Jim disassembled it, cleaned it and fabricated two new P-lead wires. I had to order two new condensors (noise filters), which Jim assembled for me.
Yesterday I made it to the airport after 2 weeks of being gone and recouping from a herniated disc. I removed the plugs to find the number One-bottom plug drenched in oil. Others were clean and some were soot-coated, but not too bad, really. Is the oil on the plug a result of the rings not yet seating (this is a zero-time overhauled engine)?
After installing the ignition, condensors and P-leads, reinstalling the plugs, I fired her up. It ran relatively smooth with equal drop in RPMs on both right and left. I taxied to the run-up area and did some tests. It was still running well on both mags at this point, but not smooth, like I would expect from a "new" engine. I went back to the hole and turned it off. After a few minutes I repeated the whole procedure. This time the left mag check had the engine sputtering pretty badly, the right mag check was ok.
I am guessing I fouled the Nr 1 bottom again? I lean the mixture while taxiing, of course and follow the Cessna 170 recommended run-ups. Is this going to happen every time I start the engine? I guess she really just needs to fly....but is it going to, performing like this?
Thank you for your input.

You need to stop running that engine unless your going to fly it to break it in. Probably oil fouled the plug. Clean it and get everything else ready for flight.

Then go fly it. Fly it hard. You want to apply full power for take off and never pull it back except for keeping it under red line until it is time to land. This means between 2600 and 2700 rpm continuously. You are not doing pattern work. Your running the engine hard to break it in. Orbit your airport for 15 or 20 minutes. Observer oil pressure and temperature. Land and leak check it and check the oil. If all is right go back up and run it hard again between 2600 and 2700 rpm continuously for an hour or more. You need to run it hard like this until your oil use stabilizes. Depending on your cylinder type this can take 5 minutes to 20 hours of hard operation. I'd run it hard at least 10 hours.

Stay as low as possible, just run around the pattern at full throttle and at pattern altitude as previously advised. Stay within gliding range of the runway until you feel comfortable with the way the engine is running. Ground running and low power operation of the engine can glaze the cylinders with oil coke and they might never break in.

Maximum manifold presure yields maximum cylinder combustion pressure and that is what seats the rings. Full throttle is the best you can do. Don't worry about the bearings, seals, other moving parts, they are in as good shape as they ever will be right after the zero-time overhaul you described.

Wow! I've never seen such a consistent answer on this forum to date. Ok, ok...I'll go fly it. Jim Musgrove also said the same thing... I guess I have been so worried about engine Nr 2 being a lemon, too, that I have been focused too much on that. I'll get the rest of the pieces back together, paste the annual in my book and get off the ground. Thank you all for pulling my head out of....

Shawn

The sand?

In keeping with the PG rating of this forum...sure, sand...