Right spark plug?
#1710465
12/14/14 04:16 PM
12/14/14 04:16 PM
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Joined: May 2005
Posts: 127
Missoula, Montana
ChadP
OP
member
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OP
member
Joined: May 2005
Posts: 127
Missoula, Montana
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After two years of trying to get it tuned, finally took the advice of many here on Moparts and dumped the Edelbrock 750 carb. Engine is mild 440, stock intake and exhaust manifolds, 10 to 1 compression, little more aggressive cam than stock. Put on an Edelbrock 600 carb and new plugs and it's running better than ever. Plugs that were removed are Autolite 85's. All plugs were black (not wet, but black). Does that mean the 750 was running too rich, or is the plug too cold? Before going to different plug, I'll put some miles on the new carb, then pull a plug and look at it. If I need to go to hotter plug, what would you recommend for this engine?
'65 Coronet 500
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Re: Right spark plug?
[Re: ChadP]
#1710466
12/14/14 05:14 PM
12/14/14 05:14 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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too rich not too cold & the excessive richness might (& very likely) might have been from too much pumping/choke/float setting/needle/seat leaking as opposed to it being jetted too rich but I dont know the OE 750 jetting (if it's rich or lean) or what you have in there now so I am just thinking out loud. There have been some comprehensive plug threads in the past with the gist of em being the cheap offshore materials/stuff being outsourced causing problems. I'd glassbead your Autolite 85's (some ain't OK with that, I am) & toss em back in (or a new set if preferred) & you'll be fine.
live every 24 hour block of time like it's your last day on earth
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Re: Right spark plug?
[Re: ChadP]
#1710467
12/14/14 05:16 PM
12/14/14 05:16 PM
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Joined: Apr 2012
Posts: 18,880
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RSNOMO
Moparts Torchbearer
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Moparts Torchbearer
Joined: Apr 2012
Posts: 18,880
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Re: Right spark plug?
[Re: ChadP]
#1710468
12/14/14 05:44 PM
12/14/14 05:44 PM
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Joined: Jun 2008
Posts: 3,916
usa
lewtot184
master
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master
Joined: Jun 2008
Posts: 3,916
usa
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Quote:
After two years of trying to get it tuned, finally took the advice of many here on Moparts and dumped the Edelbrock 750 carb. Engine is mild 440, stock intake and exhaust manifolds, 10 to 1 compression, little more aggressive cam than stock. Put on an Edelbrock 600 carb and new plugs and it's running better than ever. Plugs that were removed are Autolite 85's. All plugs were black (not wet, but black). Does that mean the 750 was running too rich, or is the plug too cold? Before going to different plug, I'll put some miles on the new carb, then pull a plug and look at it. If I need to go to hotter plug, what would you recommend for this engine?
all those 750 and 800 edelbrocks are calibrated way too rich. easy fix.
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Re: Right spark plug?
[Re: Big Wedge]
#1710471
12/14/14 11:45 PM
12/14/14 11:45 PM
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Joined: Jul 2007
Posts: 11,836
Florida
mopar346
Let me tell ya about fat chicks!
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Let me tell ya about fat chicks!
Joined: Jul 2007
Posts: 11,836
Florida
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Ya'll do know plugs aren't really expensive don't you?
Careful, your character's showing!
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Once I switched the race cars to good ignitions, doing away with the old dual point unassited stock type ignitions, I found that one set of plugs would last a long, long time. Nothing wrong in my book on resuing spark plugs that aren't worn out as long as their cleaned and gapped properly 
I bought a Champion Brand blaster type spark plug cleaner when my airplane spark plugs got to be $16.00 each, that motor had 12 of them and where usually good for 300 to 500 hours before being worn out enough to have to replace them. I had to remove and inspect them on every 50 hour or annual inspection. The FAA authorised A&P mechanic had to approve reusing them so I would remove them and clean and regapped them before he got there 
Those where dual massive gap insulated type spark plugs and part of the FAA regulated items on the airplane so they have to pass inspection to be able to reuse them 
Some of us have to watch what we spend on our toys, some don't 
. no telling how much money i've spent on that stuff.