![]() |
I will look at the fuel flow and other suggestions. The only thing I changed was the two p-mags. There is something amiss. May take some searching but should find a solution
|
Did you install the jumper (piece of wire) between pins 2 and 3, or not?
This jumper runs the A curve, which is retarded more than the B curve. Another option is use the B curve and use the EICAD program on your computer to set the timing the same as your standard Mag by setting the max advance to 25 degrees. Mine ran hot at first and I brought it back to Normal settings, during this process I also switched my top baffle seals from Vans standard material to McFarlane cowl saver material. I was able to make one continuous piece along each side and the back, vs. segmented pieces. I also had a gap at the front inlets, outboard edges, and with the new material, made sure they tucked behind the sides of the inlets. Despite hours of baffle and jetting work, this was the smoking gun; what I thought was a good seal, was not. CHT?s run cool now and have advanced the timing back to 31.4, so far... |
Tim is based about eight miles from me and when he installed the P-mags, I used the EICAD program from E-mag to set the Advance Shift to a -1.4 degrees on both his P-mags (I also lowered his Max Advance by 1.4 degrees), which puts them at 25.2 degrees for takeoff. As with any custom configuration on the P-mags, do you not install "the jumper".
After talking with Tim on the drive in this morning, I do not believe his issue is with the P-mag or fuel delivery. The reason being is that if either were the issue, then all the CHT's would be high due to bad timing or a lean mixture. If he was injected, I would imagine it is possible that a jet could be clogged forcing #3 to run lean. That brings us to two possible issues, either a baffle seal around that cylinder or a leak on the intake tube for #3. He is going to inspect the intake tube gaskets and hopefully install the cowling and inspect the seals with his borescope. (His prop is out for an inspection, so no flying for a week or two.) I will also stop by his hangar later this week and verify the P-mag timing is correct. It was correct when we left the hangar after I set them but it never hurts to verify such things. A thought for all of you installing P-mags but are not planning on an EICommander; Tim does not have an EIC but he did bring the connections for one into his cockpit and terminated them with two female DB9 connectors under his panel. This allows for easy adjustment with the EICAD program. Should he ever buy an EIC, he can simply make a Y cable that goes from both DB9 connectors to the EIC's DB15 connector. |
Just a little more information. when I did my first test flight with the P-Mags at cruise I was running the following.
8,000 ft OAT 32 RPM 2270 Manifold 21.9 CHT #1- 326 #2- 348 #3- 345 #4- 354 |
Quote:
Keeping the nose down and climbing at higher airspeed and lower vertical speed also helps... It's great that we can go up at 1500-2000ft/min but doing so reduces airspeed, airflow over the engine, and its ability to carry heat away. |
Tim, please confirm ;
1. This happened after installing pmags. No other changes to the aircraft. 2. It only happens on climb. 3. It only is effecting no. 3 cylinder. Question-------are you still running aircraft spark plugs or did you switch to auto plugs? |
This thread was started with respect to an O320 that probably has a MA-4 carb which operates quite differently than the carb that you would expect to see on a O360. With the MA-4spa, it is my understanding that throttle position doesn't effect the "enrichment" circuit as it does on the larger carbs.
|
A friend and his carbureted RV-6 recently had the same issue with one P-Mag. We built the cable to connect it to the computer and re-programmed the P-Mag to reduce the Adv Shift and Max Adv (as well as Max RPM). Current settings are as follows but we're still tweaking.
Adv Shift: -1.4 Max Adv: 36.4 (this is affected by Adv Shift so current max is actually 35) Max RPM: 2816 Temps are now well under control with no noticeable power loss. Someone above mentioned the P-Mag is not configurable. It certainly is but not to the extent of some other systems. Cost of making the cable is about $10 and takes less than an hour. You can run it though the firewall to allow changes by a co-pilot while flying or just tie it down in the engine compartment for ground adjustments. PM me if you'd like more information. |
Quote:
Regarding your RPM limit, I would raise that up one notch to just over 3,000 RPM. It is easy to hit 2816 and when you do, the ignitions will stop firing, dumping raw fuel into the exhaust. When the prop slows down and the ignition starts firing again, that raw fuel in the exhaust will light off with a LOUD bang. That causes the pilot to need to change their underpants as soon as they land. |
Quote:
|
| All times are GMT -6. The time now is 09:22 AM. |