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#1
06-27-2007, 03:38 PM
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spark plug black and wet
my combo :
1969 rebuilt 400ci, h-beam rod, hypereutectic piston, 062 heads home ported, rpm performer with 800 quadrajet (rebuilt with cliff ruggle book), stock distributor with crane xri, new accel 300 wire set, new distributor cap my problem : the car start, run great but there a sound like a misfire. i check the spark plug and the cyl n°1 spark plug is black and wet while the other are good. the spark plug fire well outside the head. check the compression and it's ok on all cylinder coolant level is good what can it be ? |
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#2
06-27-2007, 03:47 PM
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Pull the valve cover and see what your #1 rocker arms are doing.
__________________
Greg Williams, Wabasha, Mn. 65 GTO, 455, DCI ported 6x heads, Isky Rpm 300 cam, 2-4's, 4 speed, 3.31 |
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#3
06-27-2007, 03:53 PM
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Quote:
don't timing them but seems to be good in height and duration the pushrods seem to be straight |
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#4
06-27-2007, 04:03 PM
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Hi,
Is the wetness oil or gasoline? If oil, then you may have a case where the gaps on the rings have aligned and are letting crankcase oil into the cylinder or the valve stem seal is torn or leaking. If gas, then the plug may not be firing in the cylinder. Swap it with another plug from an adjacent cylinder and run the engine. Your carb could be dribbling gas due to leaks. The gas would head for the cylinder that is connected by the lowest passage in the intake manifold. That could cause a wet plug while the car is setting still. Try driving in in different directions and then check all the plugs. If more than one is wet, then the gas is getting slung around while the car in in motion. Hope this helps. Mike
__________________
1968 Pontiac GTO 462CID, 4-Speed Manual, 3.55 rear. Aleutian Blue exterior, 219 Teal Blue interior. Chrome bumper, AM & 8-Track and Rally II Wheels |
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#5
06-27-2007, 04:09 PM
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Quote:
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#6
06-27-2007, 05:03 PM
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Even though you mentioned the plug firing outside the head, I'd temporarily swap another plug wire in place and see what happens.
__________________
 frittering and wasting the hours in an off hand way.... 1969 GTO, 455ci, 230/236 Pontiac Dude's "Butcher Special" Comp hyd roller cam with Crower HIPPO solid roller lifters, Q-jet, Edelbrock P4B-QJ, Doug's headers, ported 6X-8 (97cc) heads, TKO600, 3.73 geared Eaton Tru-Trac 8.5", hydroboost, rear disc brakes......and my greatest mechanical feat....a new heater core. 
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#7
06-27-2007, 05:15 PM
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I agree; the fact that the plug is wet indicates it is not firing. Replace the plug and if the same situation persits, replace the spark plug wire.
George
__________________
"...out to my ol'55, I pulled away slowly, feeling so holy, god knows i was feeling alive"....written by Tom Wait from the Eagles' Live From The Forum |
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#8
06-28-2007, 01:39 AM
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Quote:
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#9
06-28-2007, 02:23 AM
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Is it possible that it is in the distrib cap?
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#10
06-28-2007, 04:37 AM
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Quote:
i think i will put my old PERTRONIX instead of the new CRANE XRi, just to see ...... Last edited by wr17; 06-28-2007 at 05:46 AM. |
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#11
06-29-2007, 05:50 AM
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i have replace the CRANE XRi with my old PERTRONIX and......... it works really better.
i can hear and feel all 8 cylinder. but the n°1 spark plug is still wet, only on one side and less than before. it looks like oil, but there's no blue smoke on the exhaust the piston head is black and wet too. i'm still searching what happen if you have some ideas, i listen to you |
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#12
06-29-2007, 03:11 PM
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Did you replace the spark plug at the time of the swap. The plug might not be "cleaning up."
__________________
"The Mustang's front end is problematic... get yourself a Firebird." - Red Forman |
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#13
06-29-2007, 03:52 PM
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Quote:
good idea; i will try another one thanks |
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#14
06-30-2007, 11:13 PM
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are you running a pvc line into the intake?? if you are running it into the intake runner in the front. you might be sucking a little oil into the intake from the pvc.
__________________
1970 firebird, 468, e heads, |
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#15
07-01-2007, 03:23 AM
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Quote:
 but yes, very close to the #1 cyl i will try to disconect the PCV line i have try other spark plug with the same result. now the #1 cylinder work (i can hear and feel it) but the spark plug is still wet and i think it's not gasoline (i've try to fire it just after remove it) but OIL. there's no blue or black smoke at the exhaust, the oil level is correct. but if it's not that what it can be : head's cracked ? valve stem seal ? cylinder ring ? |
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#16
07-01-2007, 06:59 AM
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it cant be the rings if the compression is good. if the bulid up on the plug is black but fluffly carbon than that cylinder is running rich and also telling me that it is running too cold to burn off the deposits. now if it is black but has a wetness to it and feels oil like then most likely it is oil ether getting into the cylinder by bad valve stem seals or piston rings that havent seated fully yet. Im curious how many miles are on this engine? it might help us figure this out.
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#17
07-01-2007, 09:46 AM
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jut taking out the intake manifold, and found a lot of oil above the valve. i've made turning the engine with the starter and see ome oil comming from the top of the valve. i think i's a worn valve guide because the valve stem seal are new. |
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