pettrix

AC Delco R45S in a 455 street motor.

Does that look like carbon fouling or oil fouling?

JOHNNYOLDS442

both, should be burning light brown no?


here’s mine R43

Cosmic Charlie

rocketraider

Both though looks more like oil. A 45 heat range ought to be able to burn that off unless you have oil control or weak ignition issues. Still on points, or electronic?

droldsmorland

Ignition system up to snuff?

All plugs look like that?

Oil control. Or the loss of it.
Valve guides, seals, and or rings.

How many miles on it. does it "use" oil?

pettrix

It currently has the AC Delco 43 plugs but will change to a 45 plug.

It has an aftermarket HEI MSD ignition system so the spark is hot.

455 Motor has about 23,000 miles on it since the rebuild. It does use some oil.

Only cylinder #6 looked like that. The other plugs looked OK on the passenger side (2 - 4 - 8). Still need to check drivers side.

Vintage Chief

If only #6 looks like that I'd check (1) integrity of the plug itself (gap, electrode, casing, etc. and change out #6 plug); (2) integrity of #6 dizzy/spark plug wire (seating of wire in dizzy and spark plug); (3) positioning of #6 dizzy/spark plug wire (ensure wire is not too long, ensure wire is not laying directly on top of other spark plug wires - in particular running over & under another spark plug wire where #6 wire pulse continuity jumps to another wire); (4) if overly concerned and piece of mind perform BOTH a dry and wet compression test (e.g. determine in particular if #6 cylinder increases compression between dry & wet compression test).

Ozzie

Since #6 is unique in a negative way, you could explore the possibility that the shortfall is in the plug or the voltage coming to it. If you have a spark plug tester, you could clean the plug up and see what it looks like in the tester, firing, under pressure. If the tester is unavailable, you could just replace the plug and run it some more. It appears to have too much deposit within.

pettrix

What is the Champion plug version of the AC Delco R45S?

Is it Champion RJ12Y or #14?

Vintage Chief

https://www.sparkplug-crossreference.../AC_DELCO/R45S

Killian_Mörder

If the other 7 are burning clean and there genuinely is loss of oil taking place, the oil has to be going somewhere. In which case, a hotter plug will not make the plug look prettier. It'll just fire longer before fouling.
Better hope that it's just a brittle valve seal causing the loss and not a cracked oil ring. The seal can be easilly replaced, while compressed air holds the valve closed

pettrix

I put in the Champion #14 (RJ12YC) plug and gaped them to .045. It was hard to start and ran rough.

Should I regap to .040 or .035 ?

rocketraider

Go back to .040 and then to .035 though I would think an MSD should fire .045 easily. Possibly a bad set of plugs. I've known people who refused to run Champions for those reasons though I've "usually" had good experience with them.

I had one 72 Olds 350 that absolutely would not tolerate the specified Bosch plugs. After 2nd set did the same thing, I went back to AC and Autolite.

JOHNNYOLDS442

Do you have points?
With points it’s 35
check your firing order sounds like you crossed wires maybe too

Vintage Chief

A smaller gap will generally create a smaller arc (spark), a smaller arc generally equates to a weak(er) spark, a weaker spark generally equates to poor performance.

Vintage Chief

I had the EXACT same scenario described by rocketraider on my '71 CS. I generally like Bosch and I used Bosch in my Indian motorcycle. I thought I'd give Bosch a try on the '71 CS. Turned out miserable. I too am running Autolite spark plugs. Champion seems to work fine in all of my yard equipment, tractors, chain saws, power washer, generators etc. I've been OK w/ NGK in the same equipment. Once I found Autolite works the best I'm not going to be switching spark plugs on the '71 CS. I will say this, I've never simply changed spark plugs on an automobile engine without performing a full tune-up - dwell, timing & A/F (vacuum) adjustment after having installed new spark plugs. That's something you might need to consider.

Again, however, read my statement in Post #7.

edzolz

There is a sticky for all spark plug cross reference in the technical section.

rustyroger

Seems to make sense but I think this need qualifying.
A spark hot enough (both voltage & duration) to reliably ignite the mixture is all that is required. A low compression flathead engine won't need much. A top fuel dragster engine will need a massive kick.
If the spark is timed correctly and fires the mixture properly a lightning bolt wont make it any better. Not what the aftermarket ignition manufacturers want you to know, but there it is.
The system cars leave the factory with will be entirely adequate for the fuel available when the car was built, modern fuels might need a hotter spark, but I've found no problems using regular unleaded with older engines for normal use.

Roger.

pettrix

I have a PetTronix Flamethrower distributor with a Mallory Promaster Coil

I only removed 1 wire at a time, so no wires got crossed, plus I rechecked it and the wires are labeled for each cylinder.

Killian_Mörder

The volatility of gasoline itself hasn't changed. That of any added-in alcohol could be a different story. Here where up to 10% ethanol is available, spark plug insufficiency has never been an issue

pettrix

Put the gap back to .035 and it ran good.

On a different front. I noticed after running the motor and parking it. I removed the oil fill cap and there was some smoke coming from there. What causes that?

Fun71

That is blowby from the combustion chambers; the amount varies with ring and valve guide wear, tolerances, etc.. The PCV pulls the blowby gases into the intake when the engine is running, but when the engine stops some is left in the crankcase.

pettrix

So this is "normal" for smoke to be present normal when off?

rustyroger

Yes, but not a smoke screen. Quite possibly you might be seeing water vapor from the crankcase evaporating on an engine just getting warm.

Roger.