How do those spark plugs look?
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From: Lakeland, FL
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St. Jude Donor '03, '06, '17
How do those spark plugs look?
Not sure if I need colder or hotter plugs or if those are fine.. They are AC Delco 7..
2 of the electrodes are very dark, almost black while the other ones are tan..
Gap seems awefully big.. Haven't measured it but that looks way too big.. What do you guys think?
2 of the electrodes are very dark, almost black while the other ones are tan..
Gap seems awefully big.. Haven't measured it but that looks way too big.. What do you guys think?
Last edited by GrandSportC3; Dec 30, 2015 at 10:35 PM.
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St. Jude Donor '03, '06, '17
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St. Jude Donor '03, '06, '17
You can see the distrubutor in this pic. I think that it's a Mallory..
Last edited by GrandSportC3; Dec 30, 2015 at 09:14 PM.
Racer
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From: Fredericksburg Va.
Are you having a problem ? Why are you asking about the plugs ?
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St. Jude Donor '03, '06, '17
Sometimes, when I accelerate harder, the car doesn't seem to fire on all 8. Feels like 1 or 2 cylinders are missing.. If I easy off the throttle and then hit it again, if often goes away. I will also look at the timing and if that looks ok, I will look at the valve springs and look if I see any issues. This only happens when accelerating heavily.. Doesn't happen on part throttle or moderate acceleration. I thought that it had to do with the same reason as my hesitstion issue. With bigger jets on the carb, the hesitation went away but the misses on heavy acceleration remained. Might also be lack of octane.. not sure. I usually run 93 but filled up yesterday at WAWA which only has 92 octane.. Problem seems worse with 92 octane.
Car should have stock compresson as it appears that the block was never decked (all numbers still there)
Car should have stock compresson as it appears that the block was never decked (all numbers still there)
Last edited by GrandSportC3; Dec 30, 2015 at 09:31 PM.
Racer
Joined: Feb 2011
Posts: 252
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From: Fredericksburg Va.
Sometimes, when I accelerate harder, the car doesn't seem to fire on all 8. Feels like 1 or 2 cylinders are missing.. If I easy off the throttle and then hit it again, if often goes away. I will also look at the timing and if that looks ok, I will look at the valve springs and look if I see any issues. This only happens when accelerating heavily.. Doesn't happen on part throttle or moderate acceleration. I thought that it had to do with the same reason as my hesitstion issue. With bigger jets on the carb, the hesitation went away but the misses on heavy acceleration remained. Might also be lack of octane.. not sure. I usually run 93 but filled up yesterday at WAWA which only has 92 octane.. Problem seems worse with 92 octane.
Car should have stock compresson as it appears that the block was never decked (all numbers still there)
Car should have stock compresson as it appears that the block was never decked (all numbers still there)
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From: Lakeland, FL
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St. Jude Donor '03, '06, '17
When looking at a fairly stock 68, I would assume that 36 degrees total timing should be fine, right?
Last edited by GrandSportC3; Dec 30, 2015 at 10:30 PM.
Racer
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From: Fredericksburg Va.
Doesn't backfire through the carb.. only misses when accelerating heavier. Seems to be worse on 92 octane compared to 93 octane. Plug wires look like they are older but couldn't see any damage. Might replace them anyways to troubleshoot. If the problem persists with new wires and plugs (and after playing with the timing), I will have to look at the valve springs.
When looking at a fairly stock 68, I would assume that 36 degrees total timing should be fine, right?
When looking at a fairly stock 68, I would assume that 36 degrees total timing should be fine, right?
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There are MANY possibilities with this one. Does the Mallory dizzy have an electronic ignition system? If so, is the coil you are using matched to that system? Is that system powered by 12vdc directly, or does it still have the original resistance wire going to the coil (as it would have if the car originally had a points-type ignition)?
If you have an electronic ignition system that is powered as required by that system, and the coil is designed to provide a hotter spark, then you can have a .040+" gap on the PROPER plugs for the engine and you shouldn't get spark miss. Or, you can re-gap to .035" and probably run fine.
Only you know what ignition system/components are on your engine. But, the components of that system need to be compatible with each other and the spark gap is set according to what you have and the needs of the engine.
If you have an electronic ignition system that is powered as required by that system, and the coil is designed to provide a hotter spark, then you can have a .040+" gap on the PROPER plugs for the engine and you shouldn't get spark miss. Or, you can re-gap to .035" and probably run fine.
Only you know what ignition system/components are on your engine. But, the components of that system need to be compatible with each other and the spark gap is set according to what you have and the needs of the engine.
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St. Jude Donor '03, '06, '17
Does it feel like it's starving for fuel like it falls on its face or do does it feel like you are running on 7 or even 6 cylinders. If you're dropping cylinders you would hear it through the exhaust tone however if it's starving for fuel it would just hesitate real bad. I'm still trying to determine if it's fuel or spark thats why I keep asking questions.
Last edited by GrandSportC3; Dec 30, 2015 at 11:04 PM.
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From: Lakeland, FL
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St. Jude Donor '03, '06, '17
There are MANY possibilities with this one. Does the Mallory dizzy have an electronic ignition system? If so, is the coil you are using matched to that system? Is that system powered by 12vdc directly, or does it still have the original resistance wire going to the coil (as it would have if the car originally had a points-type ignition)?
If you have an electronic ignition system that is powered as required by that system, and the coil is designed to provide a hotter spark, then you can have a .040+" gap on the PROPER plugs for the engine and you shouldn't get spark miss. Or, you can re-gap to .035" and probably run fine.
Only you know what ignition system/components are on your engine. But, the components of that system need to be compatible with each other and the spark gap is set according to what you have and the needs of the engine.
If you have an electronic ignition system that is powered as required by that system, and the coil is designed to provide a hotter spark, then you can have a .040+" gap on the PROPER plugs for the engine and you shouldn't get spark miss. Or, you can re-gap to .035" and probably run fine.
Only you know what ignition system/components are on your engine. But, the components of that system need to be compatible with each other and the spark gap is set according to what you have and the needs of the engine.
Not sure about the coil..
Racer
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From: Fredericksburg Va.
It's not fuel starvation.. it definitely is missing on 1 or 2 cylinders when accelerating heavier.. Under moderate acceleration, no issues..I doubt that it is fuel related.. I bet that it's spark, timing or springs. Had a similar issue on a 383 a while back and it turned out to be a bad valve spring.
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St. Jude Donor '03, '06, '17
Ok. Let's go with spark. As 7T1 has stated you should make sure all that add on electronics is compatible. Check primary and secondary circuits. I would also ohm out those wires. Go ahead and pull the valve covers to check the springs if you want to that's certainly easy enough to do. Don't want to spend your money for you but I'm not sure I wouldn't scrap all the add on ignition parts and replace with standard stuff.
Last edited by GrandSportC3; Dec 30, 2015 at 11:51 PM.
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St. Jude Donor '03, '06, '17
Burning Brakes
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From: Austin TX
Thread Starter
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St. Jude Donor '03, '06, '17
Engine only has about 4000 miles since it was rebuilt when owned by the previous owner. It was rebuilt a few years ago but he only drove the car very little.. Haven't changed the plugs yet.. Just bought them.. Got the same exact plugs but they are a little different now.. The AC Delco 7 Rapidfire are now Platinum plugs with slightly different design (don't go as deep into the chamber as the old version)
They are gapped at .035 and I will try that first and increase the gap if needed.
Last edited by GrandSportC3; Dec 31, 2015 at 01:17 PM.
Burning Brakes
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From: Austin TX
That's the lowest oil consumption I've ever had on a C3.. There is a small leak somewhere as there are a few drops at the garage floor ever time..
Engine only has about 4000 miles since it was rebuilt when owned by the previous owner. It was rebuilt a few years ago but he only drove the car very little.. Haven't changed the plugs yet.. Just bought them.. Got the same exact plugs but they are a little different now.. The AC Delco 7 Rapidfire are now Platinum plugs with slightly different design (don't go as deep into the chamber as the old version)
They are gapped at .035 and I will try that first and increase the gap if needed.
Engine only has about 4000 miles since it was rebuilt when owned by the previous owner. It was rebuilt a few years ago but he only drove the car very little.. Haven't changed the plugs yet.. Just bought them.. Got the same exact plugs but they are a little different now.. The AC Delco 7 Rapidfire are now Platinum plugs with slightly different design (don't go as deep into the chamber as the old version)
They are gapped at .035 and I will try that first and increase the gap if needed.
Anyway, if you change your plugs and the miss goes away, even temporarily, you'll know the problem isn't electrical in nature.
Last edited by 454Luvr; Dec 31, 2015 at 01:24 PM.