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Re: What causes stinky idle with performance cam?
[Re: 451Mopar]
#1271751
07/23/12 12:50 PM
07/23/12 12:50 PM
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Joined: Apr 2005
Posts: 12,271 Overpriced Housing Central
RobX4406
I Live Here
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I Live Here
Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
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46 degrees of overlap and it has a stinky idle?
That's not a very large cam or have much overlap.
Here's what I might do. Double your initial and reset the carb using a vacuum gauge to highest reading, leanest mix setting. Then maybe out 1/8 turn. As long as it starts when warm without dragging the starter, that's a good starting point.
I don't even run stock 318's at 8 BTDC, nothing I have has less than 14 initial. Throw the book in the trash because the timing events from an FSM were not to optimize performance. They had emission profiles to meet, even back then. I'd figure out the total and tailor it after setting initial before you hurt the engine.
If you don't have a timing tape or marked balancer, find a post with "hillbilly timing tape" and do that so you can determine total. Just don't drive around with an excessive amount of total, bad things happen... It takes some work to get ignition timing right, but, the benefits of a clean running engine are worth the time.
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Re: What causes stinky idle with performance cam?
[Re: RobX4406]
#1271752
07/25/12 01:14 AM
07/25/12 01:14 AM
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Joined: Jul 2008
Posts: 259 Khemi, Stygia
Mebsuta
OP
enthusiast
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OP
enthusiast
Joined: Jul 2008
Posts: 259
Khemi, Stygia
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Okay, the tab on the timing cover goes up to 15, so I guesstimated and set it to 18 degrees initial BTDC. Set the idle back down to 700 rpm. Now getting 17 inches manifold vacuum and idle is cleaner. Took it for a little ride and it is happy; no castanets and easy starting. Will revisit in more detail later and will not be afraid of a more bumpty cam in the future. Thanks.
68 Roadrunner. 383 4-spd. Beat up.
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Re: What causes stinky idle with performance cam?
[Re: Mebsuta]
#1271754
07/25/12 06:30 PM
07/25/12 06:30 PM
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Joined: Apr 2005
Posts: 12,271 Overpriced Housing Central
RobX4406
I Live Here
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I Live Here
Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
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Quote:
Okay, the tab on the timing cover goes up to 15, so I guesstimated and set it to 18 degrees initial BTDC. Set the idle back down to 700 rpm. Now getting 17 inches manifold vacuum and idle is cleaner. Took it for a little ride and it is happy; no castanets and easy starting. Will revisit in more detail later and will not be afraid of a more bumpty cam in the future. Thanks.
Cool you got it sorted out.
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Re: What causes stinky idle with performance cam?
[Re: Mebsuta]
#1271755
07/25/12 08:26 PM
07/25/12 08:26 PM
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Joined: Mar 2007
Posts: 3,298 West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,298
West Coast, USA
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Quote:
Okay, the tab on the timing cover goes up to 15, so I guesstimated and set it to 18 degrees initial BTDC. Set the idle back down to 700 rpm. Now getting 17 inches manifold vacuum and idle is cleaner. Took it for a little ride and it is happy; no castanets and easy starting. Will revisit in more detail later and will not be afraid of a more bumpty cam in the future. Thanks.
Before you call it done, check to see how much total advance you have with the vacuum disconnected. 36 degrees total is about the maximum you want. If you haven't welded up the slots in your distributor, you are probably well past that if you're running 18 initial on an otherwise stock distributor.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's 1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: What causes stinky idle with performance cam?
[Re: jbc426]
#1271756
07/26/12 02:40 AM
07/26/12 02:40 AM
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Joined: Jul 2008
Posts: 259 Khemi, Stygia
Mebsuta
OP
enthusiast
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OP
enthusiast
Joined: Jul 2008
Posts: 259
Khemi, Stygia
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Allright I'll look at that. Need to get a hillbilly timing tape on the balancer.
68 Roadrunner. 383 4-spd. Beat up.
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