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Post By Seagull81
11-08-2022, 10:04 AM
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CC Member
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Join Date: Oct 1999
Location: Georgetown, TX. USA. Little North of,
TX
Cobra Make, Engine: SMC Motorcars 289
Posts: 831
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Not Ranked
289 Timing?
Is there a "standard" for 289 Timing? I am trying to dial in my car and it was set at near, BTC, causing a lot of backfiring (Pic). I found a 289 forum online and it suggest just setting for 8 degrees Before TDC, and it's "that simple". I'm running an MSD 6A Ignition and MSD Blaster 2 coil, and MSD distributor. Brand new plugs gapped at .044
Cannnot get pics to upload...I will try later.
Still backfiring a bit when letting off the throttle.
1. How normal is the backfiring?
2. Suggestions on setting the timing differently?
__________________
Co-founder of the Texas Cobra Club.
Dave "Ren Man"
Last edited by renaissance man; 11-08-2022 at 10:29 AM..
Reason: uploading pics
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11-08-2022, 10:18 AM
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CC Member
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Join Date: Feb 2002
Location: Dadeville,
AL
Cobra Make, Engine: Sold my EM.
Posts: 2,459
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Quote:
Originally Posted by renaissance man
I am trying to dial in my car and it was set at near, BDC, causing a lot of backfiring (Pic).
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Is BDC a typo?
__________________
Tommy
Cheetah tribute completed 2021 (TommysCars.Weebly.com)
Previously owned EM Cobra
"Never attribute to malice that which is adequately explained by stupidity." - Hanlon's Razor
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11-08-2022, 10:30 AM
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CC Member
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Join Date: Oct 1999
Location: Georgetown, TX. USA. Little North of,
TX
Cobra Make, Engine: SMC Motorcars 289
Posts: 831
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Not Ranked
@Tommy
Yes, Typo
__________________
Co-founder of the Texas Cobra Club.
Dave "Ren Man"
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11-08-2022, 11:21 AM
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CC Member
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Join Date: Feb 2002
Location: Dadeville,
AL
Cobra Make, Engine: Sold my EM.
Posts: 2,459
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Not Ranked
Has this engine run right for you in the past? If so, what changes have you made?
If it ran good in the past AND you know the timing mark on the balancer is in the correct place, then this should come down to putting the distributor in at the right place. That's usually done by turning the engine over until the #1 piston is at TDC and confirming that with the timing mark. Then drop the distributor into the hole so the button on the rotor is pointed at the #1 spark plug wire on the cap after it is fully seated into the cam gear. With that done, install the plugs and wires, and tighten the distributor hold down so you can just move it by hand. If you have vacuum advance, disconnect it and plug the hose for no vacuum leak. Start the engine and slowly turn the distributor to get the smoothest, highest idle. Check the timing with a light and compare it with the goal of about 8* before TDC. When the engine is warmed up, adjust the carb and timing for the best idle again. Then check the timing when you increase throttle to to raise the RPM to see your "all in" advance. When all looks right, tighten the hold down and reconnect the vacuum advance. There's more, but this should get you close.
__________________
Tommy
Cheetah tribute completed 2021 (TommysCars.Weebly.com)
Previously owned EM Cobra
"Never attribute to malice that which is adequately explained by stupidity." - Hanlon's Razor
Last edited by Tommy; 11-08-2022 at 11:26 AM..
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11-09-2022, 02:32 PM
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CC Member
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Join Date: Aug 2007
Location: Carlsbad,
Ca
Cobra Make, Engine: SPF 2932 with 438 Lykins Motorsports engine. Previous owner of FFR 5452.
Posts: 2,616
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Backfiring on deceleration is usually caused by an exhaust manifold leak where the headers meet the heads. Check that your header bolts are tight. All it takes is a small leak to blow the gasket apart.
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Jim
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11-09-2022, 03:16 PM
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CC Member
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Join Date: Jan 2009
Location: Las Vegas,
NV
Cobra Make, Engine: Shelby CSX4005LA, Roush 427IR
Posts: 5,627
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Quote:
Originally Posted by jhv48
Backfiring on deceleration is usually caused by an exhaust manifold leak where the headers meet the heads. Check that your header bolts are tight. All it takes is a small leak to blow the gasket apart.
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It can also be caused by a rich condition.
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Cheers,
Tony
CSX4005LA
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11-09-2022, 04:06 PM
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CC Member
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Join Date: Feb 2006
Location: Gilroy,
CA
Cobra Make, Engine: SPF 2291, Whipple Blown & Injected 4V ModMotor
Posts: 2,741
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I sort of like the idea of the backfiring, especially at night. On those long lonely drives home in the dark, the back firing is sort of like a wake up call preventing you from dosing off ...
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Help them do what they would have done if they had known what they could do.
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11-09-2022, 07:44 PM
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CC Member
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Join Date: Jan 2009
Location: Las Vegas,
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Cobra Make, Engine: Shelby CSX4005LA, Roush 427IR
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Quote:
Originally Posted by eschaider
I sort of like the idea of the backfiring, especially at night. On those long lonely drives home in the dark, the back firing is sort of like a wake up call preventing you from dosing off ...
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And also provides a little motivation for the tailgaters to back off.
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Cheers,
Tony
CSX4005LA
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11-10-2022, 05:50 AM
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CC Member
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Join Date: Mar 2007
Location: Creedmoor,
TX
Cobra Make, Engine: FFR3542K, 347 C. I., EFI, T-5, Miata Front Sway Bar, 3 Link, Red with White Stripes
Posts: 1,165
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Dave, you have a PM.
__________________
Steve
Texas Cobra Club-Austin
July 2009 FFCars Picture of the Month
FFR3542K, 347, Holley Sniper EFI, T-5, 4 Wheel Discs, 3-Link, Miata Front Sway Bar, Red with White Stripes
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