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View Full Version : 100LL fuel and TCP additive or other fuel additive in C-85-12F



Clarke Tate
05-27-2014, 12:36 PM
Hello,
Does anyone have experience with TCP additive in fuel?

I have been using 100LL in a C-85 for the few hours I have flown this aircraft.
I've read about 3 tanks mogas to one of 100LL (with an auto fuel STC of course), using TCP additive, some use Marvel Mystery Oil.

FlyingRon
05-27-2014, 04:21 PM
Forget MMO. Running 100% mogas would be fine (despite the old wives tales espoused by the same idiots who recommend the minty fresh fuel additives, your plane doesn't need lead). If you can't get unleaded, and you run into lead problems, TCP might help. Be **VERY** careful handling this stuff. Nasty (absorbed through the skin and many gloves won't stop it either).

vaflier
05-27-2014, 06:44 PM
Have used TCP in a C150 and it works well. Definitely worth using along with aggressive leaning.

Dave Stadt
05-27-2014, 07:28 PM
Have burned mogas for many hundreds of hours with no problem. Small Continentals combustion temps are not high enough to scavenge the lead in 100LL.

Clarke Tate
05-27-2014, 07:50 PM
Definitely worth using along with aggressive leaning.


It is good to hear the TCP has worked well for you.

The Stromburg carburetor on my engine is unfortunately set full rich with no way to lean. The manual for the engine states that leaning below 5,000 feet is unecessary. Lack of an ability to lean is a subject for another thread.

martymayes
05-27-2014, 07:52 PM
It is good to hear the TCP has worked well for you.

The Stromburg carburetor on my engine is unfortunately set full rich with no way to lean. The manual for the engine states that leaning below 5,000 feet is unecessary. Lack of an ability to lean is a subject for another thread.

Had the same engine/carb on my C-120. Flew it at 9,500 ft regularly with no issues. Used 100LL and auto fuel as available with no additives.

Mike Berg
05-28-2014, 07:46 PM
Flew my Cherokee 140 for hundreds of hours on auto fuel with zero problems. I have a 0200 in my Champ and burn a mixture of 100LL and 91 octane auto fuel but it runs just fine on auto fuel, too. Just make sure it doesn't have ethanol in it. I had a lot of lead fouling with 100LL in my Cherokee and did try TCP for awhile but auto fuel actually was a better option. Mike

Clarke Tate
05-29-2014, 04:54 PM
Thanks Ron, Dave, Marty and Mike.
It appears that an auto fuel STC is the way to go. I'm not sure of the available fuel supply without ethanol. It appears two local airfields that had Mogas last year do not have it yet this season. I'll be looking closely at this and will try TCP until I know there are local sources for decent Mogas.

Bob Dingley
06-09-2014, 03:28 PM
Clarke, I wouldn't worry about 100LL that much. My Luscombe (A-65) ran just fine on it. I had difficulty once finding fuel going from TX to AL, so I put 10 gal of autogas in one tank. (Had 6 or 7 gal of 100LL in the other tank.) I slowly lost RPM. Every 15 minutes, I switched tanks for a minute or two, when it ran normal, switched back to autogas. Took me an hour of that to figure out that the auto gas was causing carb ice. Low vapor preasure dropped venturi temp due to greater evaporation.


Later, I asked the airport's resident expert: "Why are the O-200s having lead problems and I'm not?" He was an A&P/AI, was wearing an OX-5 pin and was older than dirt. He took my engine manual and went to the table on valve timing. he pointed out the big difference between the O-200 and 65, 85, and 90s. He said I would be fine on 100LL.


I was a Nat Guard pilot long ago flying out of AUG and we had a 10,000 gal tank of 115/145 octane. It was the DOD standard for all services. Our people added TCP with several one gal cans per 10,000 gal. Our aircraft had stenciled on the side "Min octane, 91". We all experienced epic plug fouling. I saw plugs pulled with gobs of lead as big as a lima bean. When it happened to me, I was convinced I had thrown a rod. After we moved to Bangor, we got our fuel from another unit and the fouling went away. Could be that we didnt put enough TCP in.


Bob

rwanttaja
06-09-2014, 04:05 PM
Years ago, just after buying my Fly Baby (have a C-85), I had an exhaust valve go bad. The cylinder specialist attibuted it to a lack of lead...the engine had only 25 hours when I bought it, and didn't have the lead layer that an older "more experienced" engine would. He recommended I fly at least the first 50 hours with 100LL. IIRC, he replaced my bad valve with one that was more-compatible with lead-free fuel.

This was nearly 20 years ago, not sure how much of this I'm remembering correctly.

In any case, I use both auto fuel and 100LL, and have zilch lead problems. One year was just pure 100LL, when all the car gas had ethanol added to it. Found a source without it, but, again, no lead problems for the year's operation on 100LL.

The upshot is, if you've got an "experienced" engine there's probably been sufficient lead laid down.

Ron Wanttaja

Mike Berg
06-09-2014, 05:02 PM
I agree regarding running 100LL for the first 50 hours or so. In fact, the new ECI cylinders on my 0200 recommended (maybe required) 100LL for the first 50 hours. The lead helps build a 'cushion' between the valve and the seat and promotes better seating in my humble opinion. At near 100 hours I still run a pretty heavy mix of 100LL and auto fuel but am gradually 'weaning' it off and on to 91 octane auto with an occasional drink of 100LL.

Chris Thomsen
12-19-2014, 09:55 PM
I have a Jacobs radial and run a lot of Auto with no MMO. If I can't get auto on a trip, etc. I will run MMO, but only at the published ratio of 4oz for every 10 gallons. More is not better with that stuff and I don't think the plane runs well with auto gas mixed with MMO. I run it in the oil as well. First annual I had a dead #5 cyl and after running auto for a year I'm fine, no more lead issues. The low compression engines don't like lead, and the 100LL these days has a lot more lead than 50 years ago. A mixture of 75% auto and 25% 100LL will produce the same lead content as when my plane was new in 1947! No wonder we have so many valve issues!

43-29080
05-18-2015, 09:14 AM
I've been using ALCOR TCP with 100LL exclusively for years now. My engine has a Stromberg NAS-3 carb with no mixture control installed. I found that if I didn't use TCP the plugs would quickly develop lead deposits and one of the lower spark plugs would foul, which I'd only find out about during the run-up. With TCP, there's no plug fouling at all.

I've never used auto gas except to try it initially, when I found that it sooted excessively causing plug fouling. Now, ethanol free car gas is unobtainable locally and I don't dare burn gas that contains it because it'll eat the zinc carb body.

If you're not using 100LL there's no reason to be using TCP as all it does is prevent lead deposits.

Here's where somebody chimes in to say that they've been burning car gas with ethanol in it for 15,000 hours with no ill effects.

Bill Greenwood
05-20-2015, 09:04 PM
I have never used TCP never seemed to need it in my J3 Cub with a C-90 engine. I think TCP may have been aimed more at Cessna 150s which had a problem fouling plugs in flight school use. Haven't had that problem with my plane, not sure I ahve ever had a plug foul.

When I bought it about 1985 it had approval for auto gas so I tried it a couple of times, using AMCO lead free. It ran fine, I didn't see any difference from av gas.
A Cub burns so little fuel, less than 5 gal per hour, that I didn't see much point in going to the extra trouble to save a few bucks per day, and 100 ll av gas is more convenient since virtually all airports have it.

So I have used 100 ll since and never has a problem, it seems to run the same. My engine starts first pull most times when cold and usually first or second pull when warm and idles well.
I have a Stromberg carb with a fixed mixture control with no mixture control cable. I does, I think have an arm on the carb that is wired in a fixed position and a little leaner than full rich since I live at 7800 feet and fly mostly from 5000 to 12000 feet.

FlyingRon
05-21-2015, 02:46 PM
MMO doesn't do anything for lead. It's a light solvent oil which may help in getting rid of some of the lead accumulation (particularly valves) but it's not clear it's helping with the overall health of the engine. MMO doesn't "publish" a ratio for any aviation use, just auto and marine.

Of course, it does make your engine minty fresh.

crusty old aviator
08-24-2015, 09:33 PM
Check out www dot pure-gas dot org to find locally available mogas that hasn't been adulterated by the scam the oil companies used to dupe the dopes we elected and sent to represent us in DC. I run booze-free mogas in my Franklin 90 with MMO at 4oz:10gal ratio, just like I used to in Stearmans with 220 Continentals and R680 Lycomings up front. I never had top end problems unless some dope flew off somewhere and ignorantly tanked up on the blue stuff.
As an A&P/IA, I agree that running 100LL, thinned out 4:1 with mogas, during the initial break-in period after a TOH or MOH can coat the valve stems and keep them slippery. But once they're coated, like after one or two tankfuls, avoid the blue fuel. Remember, when you take your old dog to the vet to be put to sleep, they get an overdose of blue stuff that looks a lot like 100LL. Perhaps too much 100LL is to old, low compression engines what too much sodium phenobarbital is to old dogs.

FlyingRon
08-25-2015, 06:46 AM
Not the oil companies but the corn lobby.

crusty old aviator
08-29-2015, 09:59 PM
It takes 1.18 BTU's of energy to make the quantity of ethanol that will produce 1 BTU of energy. That extra .18 BTU is produced by this funny stuff that comes out of the ground...I believe it's called oil. Monsanto and the oil industry have been bed fellows in DC for a long time. But enough about those miserable, greedy bastards, let's go flying!

Sirota
09-08-2015, 05:04 PM
MMO doesn't replace lead for lubrication but you might still want to consider it. After rebuilding the fuel valve in my Cessna 140 several times (brass on brass, typical galling) , an unidentified A&P suggested adding some MMO. That was 3- 4 years and approximately 200 hours ago and I haven't had to rebuild my valve since.