Fouling All 4 PLugs

[sastanley]

+1 what joe said. A new carb answered a lot of questions and has made my engine runs heaps better too.

[Al Schober]

Hey VT,
Jumping in here a little late, but I thought I'd ask a question - Are you using any oil?
Having good compression doesn't mean that all the rings are good. The lower ring (oil control) seems to go first. You can still have good compression but be passing oil into the upper cylinders giving a dirty transom and fouled plugs.
Just a thought..

[Vermonstah]

Don't think I am burning oil...

Al - I don't think I am losing any oil past the rings. And to be more precise, I sure hope I am not, but I will pay closer attention for that. Compression has been good since I replaced the head gaskets, oil pressure appears good upon starting, idling and cruising. I will try to get a better sense of current oil level and pay particular attention when I dump the oil in a few weeks.

I will also let it idle for 30 minutes or more and then check the plugs and see how they look. The plugs looked great after cruising 45 minutes but I did not confirm that all is well at idle.

If everything checks out, then I will move on to installing the electronic ignition.

Thanks again to all!

[Vermonstah]

After idling, 2 plugs look great, 2 less so

So, I ran the test that I described above.

Upon starting the cold engine, I throttled down to idle (~800 RPM) and left it there idling for 30 minutes. Then, I pulled the plugs and checked them.

Here is what I found:

Plugs 3 and 4 look great, as in the picture above in Post #13.

Plugs 1 and 2 are posted in order below. While not fouled, they don't look like they did after cruising 45 minutes last weekend.

Some history:
Last season, I spent chasing the cause of a #2 sticky intake valve. I had bad compression in #1 (35) and #2 (30) which led me to replace the faulty head gasket this past winter. Compression at the beginning of this season was #1 (90) and #2 (95), and admittedly I have not tested it since launch in May.

Don suggested that the engine would continue to "heal itself" (my term, he likely said something more technical) and the sticky valve would self-correct as the engine ran at temperature this season. Well, I have probably not run at temp much this entire season with a properly functioning carb, probably less than 90 minutes total. So, I will put some more hours on the engine and then re-run my idle test and check for any residue on plugs #1 and #2.

Question for the forum: should I add any MMO directly into cylinders #1 and #2?

[zellerj]

Lore from times past was it wasn't good on an engine to run at idle for long times because it "carboned up" and you had to run at full throttle periodically to blow the carbon out of it. So I would think what you found was normal. If you want to tune it further make sure your centrifugal weights under the distributor points plate are working properly, and perhaps lean the carburetor a touch, and make sure the timing is close.

Since you are worried about a stuck valve I would run another compression check and if the compression numbers look good, go sailing.

Best,
Jim

[JOHN COOKSON]

If you want to tune it further make sure your centrifugal weights under the distributor points plate are working properly, and perhaps lean the carburetor a touch, and make sure the timing is close.
Jim

Also if you run points be sure the dwell is set to spec.
To get into this a bit further...........
There is a relationship between ignition, idle speed, and idle richness.
That is to say for example if the ignition (dwell, timing, and advance) are not set to spec you will have to compensate with more idle speed and or more idle richness to even get the engine to idle.
There is also a balance between idle speed and idle richness.
The place to start is to get the ignition set to spec. Then balance idle speed against idle richness. You will eventually find the optimal setting for your paticular engine.
Have fun.

TRUE GRIT

[Vermonstah]

Not burning any oil

Least I don't think so anyway.

Lots of posts on the forum about fouling plugs, so I wanted to update my post here.

At Winter lay up, I drained 3.7 quarts of oil from my engine. From what I can determine on the forum, that seems average or maybe even above average. No, I didn't record a precise measurement for oil added at last oil change, my log only says "approximately 4 quarts" which is not very helpful in this case. I will record a more precise measurement at Spring start up.

I am ready to declare victory over my fouled plugs, which were the result of too rich mixture due to a faulty carb. There was fuel getting past the float rendering it almost impossible to regulate the mix. With too much fuel in the bowl, the bushing leaked. Time for a new carb.

After replacing with a new MMI carb, and dialing in the mixture, the fouled plugs disappeared. And I am rebuilding that old carb this winter to add to my spares kit. I presume that with a properly functioning float, that should mitigate the leaky bushing long enough to get me to safe harbor in a pinch.

Shortly after Spring launch, once the weather allows for some extended motoring, I plan to make the switch over to EI, per suggestions from John and Jim above to make sure the engine is dialed in just right. I need idiot proof and little to no-maintenance. Fewer opportunities for my mistakes.

I have certainly been the beneficiary of an abundance of useful information from this forum, hope something in this thread is helpful to another.

[Dave Neptune]

Your first plug looked like a rich idle and your second look confirms it. Your off idle colors look fine and NOT lean.
I would first try an additional 1/4 turn out on the idle screw to lean the idle a bit. If the beastie is a bit harder to start cold then your about right on the idle.

Per John, check the dwell!!! I would also try a couple of more degrees of advance while at it.

I had to idle my engine a few years ago in some really bad weather on my mooring. The harbormaster ordered all boats in the back row to keep their engines running until he could escort/pull them off. During this day I idled for 5 hours at 700. The next morning out of curiosity I checked the plugs and they looked absolutely clean and a light tan color.
Anyone who says that an A-4 won't idle well just can't adjust it properly!!!!

Dave Neptune

[Vermonstah]

Dave - thanks for the detailed feedback.

Always good to know that it is possible to get the engine dialed in just right, though I am not claiming that I can do it. But I am willing to try....

Question: since I will be installing the Moyer EI, what sequence should I follow to complete the fine tuning? Install the EI, then fine tune dwell, mix etc?

Thanks again for helping me to break this down into manageable pieces.

[Dave Neptune]

V, if it runs sort of OK, IE it starts and will idle I would not mess around further until I installed the EI. After the EI get the timing squared away. Do you have a timing lite or know how to use one? Marking where to start so after getting the EI installed you can start right back in the same spot. This will really help you out!!!

You can "set the mark" without the lite using the points! You will need a lite after that to get back to the mark though~~understand?

Dave Neptune

[Vermonstah]

I am tracking

When I put her up for the Winter, she was running and idling just fine. Not hard starting though, so I might still have the mixture too rich.

Therefore, I will back out the 1/4 turn on the idle screw (as you suggest), but AFTER I install the EI.

I am not exactly savvy with the timing light, but I have a buddy who is.

Thanks!