[PRNDL]

Hello all,
Can you take a look at these plugs and tell me what’s going on? I just installed them and have only idled this freshly rebuilt and already broken in cammed 383 stroker. The strap is shinny black. The center electrode is flat black. These are brand new Autolutes 3924. I was fighting a very rich stinky idle with this AED Holley 750 DP, but fixed it and trashed the old fouled plugs. I’m running MSD 6A and a lot of timing at idle. 36 degrees.

 

[johnsongrass1]

Wet/Shiny is poor oil control. Gas is usually dry powder.
Plug is too cold, add 2 degrees and a better brand of plug....in my opinion.

Gauging a plug on idle time only is nearly fruitless.

 

[PRNDL]

I’m still running breakin oil. I will drive it around. These are autolite 3924. I was thinking of switching to NGK. Where could the oil be coming from? The engine was just built by a reputable builder.

 

[johnsongrass1]

I’m still running breakin oil. I will drive it around. These are autolite 3924. I was thinking of switching to NGK. Where could the oil be coming from? The engine was just built by a reputable builder.

Rings, valve guides, intake manifold are most likely suspects.
A leakdown will give you a good idea on ring conditions. When the holes prepped right, the rings should have seated by the time you were done with the valve lash.
You may have to to put a good load on the engine for a little bit in order to get them wearing in well.

 

[lmsport]

excessively rich mixtures are hard on brand new rings. get it out and drive it under load and verify that the mixture is close to correct.

 

[BogiesAnnex1]

Too much fuel. This might have been too long of an effort to get it up and running, choke closed too much, carb or injection running rich, spark plug heat range too cold common especially with aluminum heads. Etc.

Need more details about cam heads, compression ratio, what’s mixing fuel and air, operating temperatures, what ignition system and spark plugs not to mention how initial start up and subsequence running have been.

These modern peanut plugs are pretty much shot once they look like this, start over with a fresh set and unless you’re using a Capacitive Discharge (CD) ignition like a 6AL or better get the plug gap to .030 to .040 inch.

Bogie

 

[ericnova72]

How do you know you fixed it, as far as the over-rich idle mixture??

Still looks rich, and maybe a heat range too cold but with no WOT run time to verify it the heat range issue can't really be decided yet.

Aluminum heads?

 

[PRNDL]

I worded it wrong. I meant the stinky rich eye burning smell. I fixed that. Looks like I need to change plugs to hotter plugs and drive it hard. Then check again.

 

[PRNDL]

If rich at idle, does regular driving clean the plugs?

 

[lmsport]

plugs are questionable. they won't clean up without many miles of driving, if ever. really need a new plug to determine correct heat range. the plug blaster will clean them up OK but don't use sand, get some pecan shells or some other media.

 

[PRNDL]

What about a wire brush?

 

[BogiesAnnex1]

What about a wire brush?

Makes matters worse as that puts scratches in the porcelain and metal surfaces with the result being a sooner and worser foul out. Just put in fresh plugs you may have to do that more than once till you get the mixture and heat range sorted out.

Bogie

 

[PRNDL]

Copy that! Thanks for the advice.

 

[PRNDL]

What do you guys think of the NGK 7938 BKR5E? They seem hotter. Not sure what happened to my words in this post.

 

[johnsongrass1]

You'll be looking for the FR5 or R5671A-8

 

[PRNDL]

Are those hot?

 

[BogiesAnnex1]

What are the heads iron or aluminum and if aluminum do they need a gasketed plug and/or are they also machined for gasketless plug?

Bogie

 

[lmsport]

NGK FR5 is a good street plug.

 

[PRNDL]

AFR 195 aluminum. They call for 3/4" reach, 14mm, gasket seat

 

[PRNDL]

I looked up the FR5 and they are exactly what AFR calls for.