#3 plug is black... |
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#3 plug is black... |
yellow75 |
Oct 20 2016, 03:59 PM
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#1
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Member Group: Members Posts: 88 Joined: 1-October 16 From: pittsburgh Member No.: 20,452 Region Association: None |
pulled the plugs on my new to me 75 1.8 with carbs today. 1,2,&4 look good grey in the center (3 electrode plugs) black around the sides. # 3 was totally black. it was idling rough so I pulled one plug wire at a time to see the difference it made. All but #3 made a difference. When I pulled #3 there was no difference at all. It has an electronic fired dizzy in it as well. Cap and rotor are new. What ya think?
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yeahmag |
Oct 20 2016, 05:17 PM
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#2
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Advanced Member Group: Members Posts: 2,421 Joined: 18-April 05 From: Pasadena, CA Member No.: 3,946 Region Association: Southern California |
Was it oily and black or sooty and black? Got a picture?
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PlaysWithCars |
Oct 20 2016, 05:54 PM
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#3
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Senior Member Group: Members Posts: 523 Joined: 9-November 03 From: Southeast of Seattle Member No.: 1,323 Region Association: Pacific Northwest |
Could be a bad plug wire. If you have an ohm meter you can check the spark plug wire to make sure that resistance is similar to the others that are working.
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yellow75 |
Oct 20 2016, 06:13 PM
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#4
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Member Group: Members Posts: 88 Joined: 1-October 16 From: pittsburgh Member No.: 20,452 Region Association: None |
sooty black. dry as a bone. Sorry I cleaned it a put it back in. Ordered new plug wires and a set of NGK RBP5ES plugs.
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zach914v8 |
Oct 21 2016, 06:01 AM
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#5
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Member Group: Members Posts: 216 Joined: 26-November 10 From: Houston Member No.: 12,426 Region Association: Southwest Region |
A quick and simple test to see if your plug wires are bad is get a water spray bottle and mist the wires gently, no need to go over board. If you have a bad wire blowing fire, you'll find it quick.
If misting doesnt tell you anything, install a spark checker on both a know good cylinder wire and the bad one. Look at the difference. A good ignition system should blow big blue 20kv spark. Just hook the end of the wire from the spark plug to the tester. That clamp on the tester, ground it to the engine. The spark tester gap is ajustable, 20kv is like a 20mm gap. |
zach914v8 |
Oct 21 2016, 06:34 AM
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#6
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Member Group: Members Posts: 216 Joined: 26-November 10 From: Houston Member No.: 12,426 Region Association: Southwest Region |
A quick and simple test to see if your plug wires are bad is get a water spray bottle and mist the wires gently, no need to go over board. If you have a bad wire blowing fire, you'll find it quick. If misting doesnt tell you anything, install a spark checker on both a know good cylinder wire and the bad one. Look at the difference. A good ignition system should blow big blue 20kv spark. Just hook the end of the wire from the spark plug to the tester. That clamp on the tester, ground it to the engine. The spark tester gap is ajustable, 20kv is like a 20mm gap. If all these these come back good, I have even more stuff to check. Keep us posted. |
VaccaRabite |
Oct 21 2016, 09:10 AM
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#7
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En Garde! Group: Admin Posts: 13,423 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
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zach914v8 |
Oct 21 2016, 09:27 AM
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#8
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Member Group: Members Posts: 216 Joined: 26-November 10 From: Houston Member No.: 12,426 Region Association: Southwest Region |
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yeahmag |
Oct 21 2016, 09:47 AM
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#9
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Advanced Member Group: Members Posts: 2,421 Joined: 18-April 05 From: Pasadena, CA Member No.: 3,946 Region Association: Southern California |
OK. So at this point you can decide to do a compression check (which I would recommend) or just work on the carb. For the carb, start by verifying everything in the idle circuit (idle jet is the correct size, properly seated, and the volume screw isn't too far off). You should also make sure you don't see any drips of fuel from that barrel when the car is running (or even stopped if it's bad).
Doesn't hurt to make sure all the basics are done too... Ignition working (see above) and valves adjusted properly. sooty black. dry as a bone. Sorry I cleaned it a put it back in. Ordered new plug wires and a set of NGK RBP5ES plugs. |
pbanders |
Oct 21 2016, 12:11 PM
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#10
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Senior Member Group: Members Posts: 939 Joined: 11-June 03 From: Phoenix, AZ Member No.: 805 |
A quick and simple test to see if your plug wires are bad is get a water spray bottle and mist the wires gently, no need to go over board. If you have a bad wire blowing fire, you'll find it quick. If misting doesnt tell you anything, install a spark checker on both a know good cylinder wire and the bad one. Look at the difference. A good ignition system should blow big blue 20kv spark. Just hook the end of the wire from the spark plug to the tester. That clamp on the tester, ground it to the engine. The spark tester gap is ajustable, 20kv is like a 20mm gap. https://www.amazon.com/dp/B0002STSBM/ |
yellow75 |
Oct 21 2016, 02:44 PM
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#11
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Member Group: Members Posts: 88 Joined: 1-October 16 From: pittsburgh Member No.: 20,452 Region Association: None |
Yeah I will do a compression check this weekend along with a valve adjustment I'll keep you posted. I ordered that cool tool as well. My son is having similar probs with his wild man Jeep so we will share it.
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yellow75 |
Oct 21 2016, 02:48 PM
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#12
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Member Group: Members Posts: 88 Joined: 1-October 16 From: pittsburgh Member No.: 20,452 Region Association: None |
OK. So at this point you can decide to do a compression check (which I would recommend) or just work on the carb. For the carb, start by verifying everything in the idle circuit (idle jet is the correct size, properly seated, and the volume screw isn't too far off). You should also make sure you don't see any drips of fuel from that barrel when the car is running (or even stopped if it's bad). Doesn't hurt to make sure all the basics are done too... Ignition working (see above) and valves adjusted properly. sooty black. dry as a bone. Sorry I cleaned it a put it back in. Ordered new plug wires and a set of NGK RBP5ES plugs. What are the proper idle jet sizes? These are 40 IDF's |
yeahmag |
Oct 21 2016, 05:06 PM
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#13
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Advanced Member Group: Members Posts: 2,421 Joined: 18-April 05 From: Pasadena, CA Member No.: 3,946 Region Association: Southern California |
I'm a Dellorto guy, but I seem to remember 55-60. I think it would be telling if you compare barrel #3 to ANY of the other three and see what's different.
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yellow75 |
Oct 22 2016, 08:22 AM
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#14
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Member Group: Members Posts: 88 Joined: 1-October 16 From: pittsburgh Member No.: 20,452 Region Association: None |
I will do that. Thanks.
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