Spark plug reading

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I have a scientific/lab microscope at work. I tried to use it but no luck.
Hysteric said:
The first plug looks good from the distance but you need to get close up photos to really be able to read them well.

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Yup, agree with Fishmen67. See post #18. A looooot of people do not seem to understand that the car maker has to select a spark plug heat range that will work under the most arduous conditions that the car could be under....such as driving in baking summer heat carrying a full load in the trunk.
Today, these cars are owned by hobbyists & that is never going to happen.....
 
340-4spDuster, thanks for the chart. Just got my '68 340 running and my plugs are about the OK to the left of Best. Running a 10.25:1 CR Sealed Power pistons with a 272° cam, RPM manifold and TQ carb. 12° initial advance and 34° total with vacuum advance operational. Timing line is about perfect right above the plug base. Just a hint of carbon deposits inside the plug so it is running a little rich. Not bad for stock jetting running at 5800'. Will play with metering rods to get the A/F ratio spot on.
I see no need for HEI ignition if your stock coil and wires are in good condition. I run an electronic ignition from the '70's with no issues. The engine will idle at 500 RPM or even lower but oil pressure starts falling at that low of RPM. Usually, it is 40 PSI at 750 but drops to 30 PSI at 500.
I would get a Leak Down tester from Harbor Freight or build one yourself. Build you own leak down tester - Search Videos and many other such sites.
This is valuable for troubleshooting many engine build issues including leaking valves, gaskets, rings, etc. Much more info than a compression test, but both are worthwhile and give different info.
 
RLF Cuda said:
340-4spDuster, thanks for the chart. Just got my '68 340 running and my plugs are about the OK to the left of Best. Running a 10.25:1 CR Sealed Power pistons with a 272° cam, RPM manifold and TQ carb. 12° initial advance and 34° total with vacuum advance operational. Timing line is about perfect right above the plug base. Just a hint of carbon deposits inside the plug so it is running a little rich. Not bad for stock jetting running at 5800'. Will play with metering rods to get the A/F ratio spot on.
I see no need for HEI ignition if your stock coil and wires are in good condition. I run an electronic ignition from the '70's with no issues. The engine will idle at 500 RPM or even lower but oil pressure starts falling at that low of RPM. Usually, it is 40 PSI at 750 but drops to 30 PSI at 500.
I would get a Leak Down tester from Harbor Freight or build one yourself. Build you own leak down tester - Search Videos and many other such sites.
This is valuable for troubleshooting many engine build issues including leaking valves, gaskets, rings, etc. Much more info than a compression test, but both are worthwhile and give different info.
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Save that chart to your photos for reviews later on.
 
Got time after work to swap in new NGK plugs BPR4ES, gapped at 0.035. I thought I may as well do a compression test as I hadn't done one yet.
Throttle wide open, Coil unplugged, all plugs out
Cyl psi
#1 167
#3 172
#5 167
#7 155* dry, added oil 164
#2 165
#4 182
#6 175
#8 175.

#7 was low so I oiled it and it helped but was still lowest at 164, it was also the most fouled.
Drive tomorrow
Thanks all.
 
Yeah, leak down test. The change in #7 with oil is a red flag for rings. I think you are going to find a glazed bore. Did you fit the rings or check the ring end gaps?
 
4sp.

You might find this interesting. People fitting plugs that are too cold. They only have a working range of about 360* F; that doubles to 720* F for the correct working range.

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I'm not overly concerned Troy. Hopefully there's no issues. I have zero plans on pulling engine(or head) unless absolutely necessary. I haven't fully stretched its legs yet. 75mph tops so far.
CFD244 said:
Good luck with the test Steve. I don't like where this thread is going. :(
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4spdragtop said:
I'm not overly concerned Troy. Hopefully there's no issues. I have zero plans on pulling engine(or head) unless absolutely necessary. I haven't fully stretched its legs yet. 75mph tops so far.
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Sounds good Steve. I followed the build thread and you were meticulous with measurements and assembly.
 
I wouldn't say meticulous, when Princess Auto tools are involved lol, but thanks. NOTES are the important part, my memory sucks lol. May need to look for cheap borescope(PA or CT)
CFD244 said:
Sounds good Steve. I followed the build thread and you were meticulous with measurements and assembly.
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So used my DIY leakdown tester. My gauges aren't reading the same(scale off, accuracy minimal?) BUT the cyl psi reads higher than incoming. Very MINIMAL can be heard thru oil fill stovepipe on ds. Everything else nada. Psi also stays consistent and doesn't drop in the cylinder. #7 is at tdc compression.
Compression on 7 was 155 dry, 164 wet.
When doing compression chk, it took quite a few cranks to build psi in all of them(8-10 revs minimum)
Here's video of leakdown.
Thanks all :thumbsup:

 
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I replaced NGK BPR6ES plugs with new BPR4ES and have put maybe another 100-150 miles on it. Out of curiosity I pulled #7 plug, the one that was fouled previously. A LOT cleaner.
I still think it's running rich(by smell) but other than that I think it's running pretty well.

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4spdragtop said:
I replaced NGK BPR6ES plugs with new BPR4ES and have put maybe another 100-150 miles on it. Out of curiosity I pulled #7 plug, the one that was fouled previously. A LOT cleaner.
I still think it's running rich(by smell) but other than that I think it's running pretty well.

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That plug is not happy. Look at all the sharp edges. They are rounded off. That's a short amount of time on the plugs.

Looking at the square edge on the ground wire you can see the rolled edges. Same with the center wire. NGK plugs don't wear as quick as a Champion but they don't last as long as an Autolite plug.

If you compare a plug out of the box to yours you can see how much the edges are rolled.

Is your timing locked out? If so, you may be putting too much heat in the plug at low speeds.

I'd be looking at doing something to get some heat out of the plug.
 
Thanks, I noticed the "rounded" areas. Wasn't sure if they were like that new or not. Or if that was an issue. I'm new to analyzing plugs lol.
Timing is not locked out. 18* BTDC, no pinging.
Thanks.
Newbomb Turk said:
That plug is not happy. Look at all the sharp edges. They are rounded off. That's a short amount of time on the plugs.

Looking at the square edge on the ground wire you can see the rolled edges. Same with the center wire. NGK plugs don't wear as quick as a Champion but they don't last as long as an Autolite plug.

If you compare a plug out of the box to yours you can see how much the edges are rolled.

Is your timing locked out? If so, you may be putting too much heat in the plug at low speeds.

I'd be looking at doing something to get some heat out of the plug.
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