The Ford Barn

mjdunn · 10-08-2014, 02:46 PM

I have a 1939 Ford with the 85 hp engine. The spark plugs at the rear on both left & right side are getting a carbon build up on the plug very quickly. In just 250 miles after cleaning. The rest of the plugs are not doing that. When I removed these two plugs the plug gaskets were oily. Does this mean that the rings on these two cylinders are letting oil through? The car does not smoke and it runs perfectly.

I am using Champion, Copper Plus 854, RH10C. Is there a hotter plug that would fit my car? If so would that help keep the carbon burned off?

supereal · 10-08-2014, 03:44 PM

If the deposit is oily black, it is likely the rings are responsible. I'd run a dry/wet compression test to see if the affected cylinders have low compression. If the deposit is a fluffy black, it means the carb is running too rich for some reason, perhaps a leaking power valve. I use Champion RJ14YC plugs in my '47. They have a long snout that buns off deposits, unlike the usual H-10 plugs. Keep an eye on the exhaust. If the smoke is black, the carb is probably at fault. If the smoke is blue, it is oil, If the smoke is white, there is an internal coolant leak.

mjdunn · 10-08-2014, 07:53 PM

Supereal - The deposit is not fluffy but hard. The exhaust is not very visible but it does does leave a black carbon on the garage floor. I know about blue smoke, from the past, but it does not have that. I don't think it is an internal coolant leak, because the coolant level has not gone down in 6,000 miles. I think I will try the plugs you mentioned. I tested the compression and all of the cylinders were 85-90.

39topless · 10-09-2014, 01:27 PM

Quote:

Originally Posted by mjdunn

Supereal - The deposit is not fluffy but hard. The exhaust is not very visible but it does does leave a black carbon on the garage floor. I know about blue smoke, from the past, but it does not have that. I don't think it is an internal coolant leak, because the coolant level has not gone down in 6,000 miles. I think I will try the plugs you mentioned. I tested the compression and all of the cylinders were 85-90.

black streaks.jpg
I've been dealing with the same symptoms. I reduced the jets 2X and runs fine now. If the photo here looks like your garage, then maybe you have the same problem. Good luck

supereal · 10-09-2014, 04:42 PM

Your compression is fine. Even though the deposits are not "fluffy", my best guess is that the mixture is a bit rich. I got tired of replacing the H-10 plugs, and switched to the RJ14YC, and they will run very long. Everybody rails against Champion plugs, but mine run fine set at .028.

mjdunn · 10-10-2014, 10:30 AM

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39topless, that is exactly what my garage floor looks like. Supereal, thanks for the information. You have been very helpfull.

supereal · 10-10-2014, 02:40 PM

You are welcome. Another check to make is your muffler. If the tailpipe is spewing carbon, tap the muffler with a hammer. If the sound is a thud, not a ping, it is likely that the muffler is partially clogged. I have seen mufflers so full of crud that you could hardly lift them off the floor. As the flow thru the muffler drops, so does the engine performance, thus the fouled plugs and erratic performance.

10-08-2014, 02:46 PM	#1
mjdunn Senior Member Join Date: May 2013 Location: Dry Ridge, KY Posts: 107	Spark plugs with lots of carbon I have a 1939 Ford with the 85 hp engine. The spark plugs at the rear on both left & right side are getting a carbon build up on the plug very quickly. In just 250 miles after cleaning. The rest of the plugs are not doing that. When I removed these two plugs the plug gaskets were oily. Does this mean that the rings on these two cylinders are letting oil through? The car does not smoke and it runs perfectly. I am using Champion, Copper Plus 854, RH10C. Is there a hotter plug that would fit my car? If so would that help keep the carbon burned off?

10-08-2014, 03:44 PM	#2
supereal Senior Member Join Date: Jul 2014 Location: Iowa Posts: 1,634	Re: Spark plugs with lots of carbon If the deposit is oily black, it is likely the rings are responsible. I'd run a dry/wet compression test to see if the affected cylinders have low compression. If the deposit is a fluffy black, it means the carb is running too rich for some reason, perhaps a leaking power valve. I use Champion RJ14YC plugs in my '47. They have a long snout that buns off deposits, unlike the usual H-10 plugs. Keep an eye on the exhaust. If the smoke is black, the carb is probably at fault. If the smoke is blue, it is oil, If the smoke is white, there is an internal coolant leak.

10-08-2014, 07:53 PM	#3
mjdunn Senior Member Join Date: May 2013 Location: Dry Ridge, KY Posts: 107	Re: Spark plugs with lots of carbon Supereal - The deposit is not fluffy but hard. The exhaust is not very visible but it does does leave a black carbon on the garage floor. I know about blue smoke, from the past, but it does not have that. I don't think it is an internal coolant leak, because the coolant level has not gone down in 6,000 miles. I think I will try the plugs you mentioned. I tested the compression and all of the cylinders were 85-90.

10-09-2014, 04:42 PM	#5
supereal Senior Member Join Date: Jul 2014 Location: Iowa Posts: 1,634	Re: Spark plugs with lots of carbon Your compression is fine. Even though the deposits are not "fluffy", my best guess is that the mixture is a bit rich. I got tired of replacing the H-10 plugs, and switched to the RJ14YC, and they will run very long. Everybody rails against Champion plugs, but mine run fine set at .028.

10-10-2014, 10:30 AM	#6
mjdunn Senior Member Join Date: May 2013 Location: Dry Ridge, KY Posts: 107	Re: Spark plugs with lots of carbon Sponsored Links (Register now to hide all advertisements) 39topless, that is exactly what my garage floor looks like. Supereal, thanks for the information. You have been very helpfull.

10-10-2014, 02:40 PM	#7
supereal Senior Member Join Date: Jul 2014 Location: Iowa Posts: 1,634	Re: Spark plugs with lots of carbon You are welcome. Another check to make is your muffler. If the tailpipe is spewing carbon, tap the muffler with a hammer. If the sound is a thud, not a ping, it is likely that the muffler is partially clogged. I have seen mufflers so full of crud that you could hardly lift them off the floor. As the flow thru the muffler drops, so does the engine performance, thus the fouled plugs and erratic performance.