Fouling Plugs questions, Petronix MR-183, Please help!

I wouldn't call it "normal", but a carbed engine runs great set to the rich side (until the plugs foul ). What spark plug are you using now? AFAIK, something like NGK BPR6EIX would be the most foul-resistant plug available for rational street use in your engine (The NGK "IX" technology is the latest in the family of spark plugs that NGK originally developed to use in 2-stroke engines -- which tend to foul because of the added oil in the fuel.)

 

if you paid Ferrari dealer rates, they should give you more insight than "install a new ignition system"

how many turns to do you have your idle mix screws out and what jetting are you running?

 

There are a few variables here to contend with. You had the engine rebuilt-what caused that to be required?

The plugs are fouling-question is just a couple of them? Same ones each time? All of them? Are they gas fouled=carb or ignition problem or oil fouled=engine problem.

The worst possibility is the rings aren't seated and sealing properly in the new engine. As a result oil is getting by and fouling the plugs. A leak down test would answer this question. I would consider using a different mechanic than the Ferrari dealer to check this.

While you had the engine rebuilt, you changed one parameter by going to a 10:1 compression ratio. This is another factor to consider as higher compression makes the ignition system work harder to ignite the more compressed charge.

If the car has a points ignition system is it all tip top condition? New points? Condensers? Cap rotor all good, condition of wires? Is the coil still in spec? Most of these can be tested or examined to determine their condition. This is the most likely area to find a problem.

Next is the fuel system-is the fuel pressure right? Too much pressure? If a non standard pump is used it can give too much pressure. Webers are designed for a low pressure supply. Use too much and it will lead to flooding and too much gas dumped into the engine=fouled plugs

Then there is the carb tune- what size idle jets are in? The rest of the jets? . As mentioned earlier the motor will run with max power on the rich side. This will cause plug fouling, hence the old "Italian tuneup" of sustained high speed high revs which heats the plugs and clears them.

Running a car too rich washes down the cylinder walls and accelerates ring wear. It this what lead to the demise of the engine originally?

Once all these possibilities are examined and the problem area determined and rectified then you could move forward.

An electronic ignition would be a good improvement. Along with a hotter more powerful coil it will help keep the plugs clear and let you run a cooler plug, which will actually help you avoid detonation with your higher compression pistons on today's poor gas.

A car with mods and Weber carbs can really benefit from time on a dyno. If you found a place that does dyno tuning and handles Weber carbs a session there would really let you get the most out of your machine. It is easy to pick up quite a few HP and torque and better driveability.

 

Fuel that has its octane rating boosted by additives (rather than 'brewed ' to higher octane) can cause this. In Australia I had a problem with Shell fuel, changes to BP and no more problems. Check with your local folk foe best available fuel.

 

Good point Steve as I went to the old style BP5ES types in my 77. Seems to be a good street plug even with a slight rich mixture. I've had them in for years and haven't had a problem. By the way I did the Pertronix conversion about 10 years ago.

 

Rammer

If your car is fouling bc the current ignition is performing poorly, then changing to a pertronix will fix that. If it is bad points, etc, you would be golden. But if the car is set up much too rich, or burning a little oil, or any of the other things listed below...

But if your car is fouling bc of any of the other possibilities, it will not help. The people who set up your engine **seem to me** to be morally required to learn and tell you why the car is fouling the plugs, and then work with you to fix it.

In general, electronic ignition is awesome. The Pertronix is nice bc it can fit in one distributor and still look totally stock, and in general works better than points. Perfectly set up points work fine, but they don't stay perfect, and so they don't stay working fine over time, necessitating fiddling.

Jonathan
Denver, CO
GT4 15302

 

The MR-183 set is based on the Ignitor I, e.g. the spark energy delivered is identical to the factory points and coil setup. If your current points/coil setup is ok you won't see a difference regarding fouling after installing a Pertonix MR-183 setup.

There is a good chance that the factory installed Marelli BZR201/202 coils have degraded over time and are now supplying less spark energy due to broken coil windings, in that case exchanging them against a set of Bosch 0221 119 030 (Bosch Red Coils) could already fix that issue. The Bosch coils are a plug and play replacement for the factory coils and can be used with the existing Marelli resistors.

As Steve posted above, exchanging the current spark plugs against a set of NGK EIX plugs is a perfect first step tackling the fouling issue, if the fouling then still persists (and the carbs are good) then either replacing the factory coils against Bosch Red coils, or installing a Pertronix Ignitor II setup (which delivers more spark energy than a points or MR-183 Ignitor I setup) would be a good next step.

Good luck,
Adrian

 

My glass car has Petronix and I have never had any problems with fouled plugs.
I also run the NGK BPEIX Iridium plugs. They have a finer tip, last for ages and are worth it.
So certainly do yourself a favour and pop a set of these plugs in and see how you go.
That said, if it is just one or two cylinders that are always the problem, then you may have a more serious problem.
I also vote for the Leak down test to see where you are at. Especially after a re-build if you are questioning it.

Steve

 

My glass car has Petronix and I have never had any problems with fouled plugs.
I also run the NGK BPEIX Iridium plugs. They have a finer tip, last for ages and are worth it.
So certainly do yourself a favour and pop a set of these plugs in and see how you go.
That said, if it is just one or two cylinders that are always the problem, then you may have a more serious problem.
I also vote for the Leak down test to see where you are at. Especially after a re-build if you are questioning it.

Steve

 

The "S" family NGK plugs are a conventional design using a 2 mm diameter center electrode and an ordinary high-nickel steel alloy for the electrode materials:
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The "IX" family NGK plugs are a much more modern design using a small ~0.7 mm diameter center electrode and an iridium alloy for the electrode materials. The iridium alloy has a much higher melting temperature, and being smaller, it runs at a much higher temperature -- which helps it run cleaner and resist fouling:
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There is another difference, the finer tip in the EIX series lowers the required coil output voltage for the spark to take place. This is especially helpful when running points and transistor ignitions. Lowering the voltage requirement makes hot and cold starts easier and helps avoiding fouled spark plugs and flooding the engine.

 

Rammer, first off, congrats on getting your baby back on the road. I know we both had the exhaust valves let go about the same time last year. Secondly, I probably should not be posting any advice because I am a rookie here and there is a pretty good chance that I am just plain wrong. But with that being said, let me share my experience. My engine seemed to take over 500 miles to settle in. At first I was going crazy adjusting the carbs – too lean and way too poppy to way too rich and stinky. I was told by a carb expert to relax and let the rings seat before going nuts. Now I have around 800 miles and things have settled down. I have the petronix ignition and I am running NGK BPR7ES plugs but have the BPR6EIX on order because I think the hotter plug will better suit my driving style during the break in.

 

I've been buying mine from RockAuto Parts Catalog (about $6.50 each), but any NGK supplier would do. However, you need to use a complete part number -- either "BPR6EIX" (which is the NGK part number) or "6637" (which is the NGK stock number).

 

Rammer,

First question is how are the plugs being fouled? If it is oil fouling, then the next question is what oil are you running? I would not recommend synthetic oil during the break-in period.

 

When I had my '78 308 GTS, I first ran BP6ES plugs, and found that they were getting dirty. Not fouled, but dirty. I switched to BP5ES, and they ran nice and clean, nice tan color like you'd want on a plug. If you switch to the Iridium plugs, stick with the 6 heat range, as the Iridium plugs seem to burn a little hotter than the standard plug.

PAD does raise a good question -- if the plugs are fouling, particularly with oil, where is it coming from? I avoided using synthetic oil in my '78, as those older engines and seals don't seem to do well with synthetic oil. I ran Castrol GTX 20W50 in my '78, and the engine loved it. Not leaks, no fouling from oil, good oil pressure, engine ran nice and smooth. YMMV, but that was my experience.

 

FWIW I am currently also running the Castrol GTX 20W50 for the break in period. The first two batches were strait up, this last change I put in the ZDDP additive.

As far as the plugs go, at first I was running with BPR7ES and was getting some fowling. Today I just tested with the BPR6EIX and everything really smoothed up. It really shows up on my AFR data as the idle O2 readings are not as ragged and are much more steady.

 

Fouling not fowling . Duhh.

 

Thanks for asking She is running pretty good so far. I did the complete rebuild myself, but was "Lucky" to have a pro right up the way to guide me through the process. I will update my first thread with pictures one of these days. How many miles do you have since your rebuild?