Author Topic: What story do my plugs tell?  (Read 2009 times)

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67428GT500

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What story do my plugs tell?
« on: March 13, 2020, 08:41:43 AM »
Here are the FR4 plugs. I think Barry R recommended them. I noted that many didn't like the RC12YC plugs recommend by Edelbrock. 
With that said, I think the heat range is a little hot. I'll let those that do this regularly opine on what changes need to be made. It does smell and seem a bit rich and I smell some fuel while driving.  Thank you. Keith


« Last Edit: March 13, 2020, 11:08:49 AM by 67428GT500 »

blykins

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Re: What story do my plugs tell?
« Reply #1 on: March 13, 2020, 09:06:37 AM »
You're showing 3-4 threads of heat on my laptop here, so the heat range is fine.  It's just rich on idle and running.  Check your floats, fuel pressure, and power valve and if they're fine, I'd start pulling fuel out. 
« Last Edit: March 13, 2020, 09:08:31 AM by blykins »
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6667fan

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Re: What story do my plugs tell?
« Reply #2 on: March 14, 2020, 07:56:02 AM »
On the the few plugs that show a timing mark it looks good timing wise.
For under $200.00 you could get an A/F reader in the car and that would answer a lot of questions.  Course, once you have a wide band in there additional questions will develop, lol. But if you like to tune it’s a must have in my opinion.

JB
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Barry_R

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Re: What story do my plugs tell?
« Reply #3 on: March 14, 2020, 08:21:51 AM »
If that is running on unleaded they are really dark - fat, fat, fat.

If its running really nice you could go up one step hotter to try & clean them up, but I agree with Mr. Lykins - pull some fuel out.

67428GT500

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Re: What story do my plugs tell?
« Reply #4 on: March 14, 2020, 09:51:04 AM »
I sent the carbs to Drew.  There were some strange issues with them he ironed out.  I am running one turn out on the mixture. They run off the secondaries so the idle screws are all but closed.  I do get a lean backfire through them sometimes when the engine is cold. Drew said that is normal. No choke, so it runs like hell until it warms up. The fuel pressure is right about 6 PSI with the Edelbrock pump Vs. 9 psi with the performance Carter.
I have nowhere to hide a fuel pressure regulator because it's all hard line through the 427 canister filter and being it's a real Shelby I don't want to modify it.
As the temps warm up I get a few idle issues and hard re-starts.

                                           

67428GT500

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Re: What story do my plugs tell?
« Reply #5 on: March 14, 2020, 09:52:22 AM »
On the the few plugs that show a timing mark it looks good timing wise.
For under $200.00 you could get an A/F reader in the car and that would answer a lot of questions.  Course, once you have a wide band in there additional questions will develop, lol. But if you like to tune it’s a must have in my opinion.

JB

JB, I would love to have an AF meter. Its a real Shelby. I have nowhere to hide it.

Thumperbird

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Re: What story do my plugs tell?
« Reply #6 on: March 14, 2020, 11:18:37 AM »
Restrict the secondary transition slot, install the dang A/F sensor, it's under the car, does not modify the car, and gives you the tool you need to enjoy your vehicle.

Barry_R

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Re: What story do my plugs tell?
« Reply #7 on: March 14, 2020, 11:52:18 AM »
The cold pop does not bother me either - just let it warm up before chasing the throttle.
One full turn out might be too much on a 2x4 deal
6psi seems about perfectly ok
I don't do much with ngk plugs so you probably got that recommendation elsewhere
I do a lot of 3924 autolite - some folks think they are "hot" but I like them
If it runs OK I would consider snugging up the idle mixture screws a 1/4 or 1/2 turn and maybe pull two jet sizes

lather, rinse, repeat


Drew Pojedinec

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Re: What story do my plugs tell?
« Reply #8 on: March 14, 2020, 01:14:54 PM »
3/4-1 turn is where most fall.
 That 1/4 turn may be 1.5-2 point on the a/f at idle. Never know till ya try.

Just hang the O2 with a zip tie, remove when not in use (they sell plugs) . They are pretty awesome.
With any tuning, ignore cold running issues unless they keep you from being able warm it up.

My car runs like poop and won’t idle Without intervention for 30 seconds. Heck even my truck does.
I don’t run a choke either.... can’t find a decent carb guy around here to install one.

Drew Pojedinec

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Re: What story do my plugs tell?
« Reply #9 on: March 14, 2020, 01:18:52 PM »
Oh, just read that “hot restart” part of your post.

Either idle screws are too far out, float levels are a touch high (ignore the sight holes) or you have an internal leak, even a tiny one.

Easy thing to turn all four floats adjusters down one “flat” of the hex and see what happens.
I recall on your car there is little fuel line insulation due to the original shelby part.... once warmed up there might be some fuel boil/vapor issues in the lines or bowl