I am experiencing some off throttle backfire through the rear carb I suspect. I replace the stock aircleaner with fresh filter.
Around 50mph coming off glass I would get backfire. Suggesting lean. Pulled the plugs to check and I saw this:
I noticed the my plug gap on NGK R plugs should be 39-43 for an EL dizzy. Adjusted to about 40 replaced with never seize and ran it. Whoa!! Much improved and better speed ~ 70mpg I get some backfire but I also not I need to have the choke pulled about 1/2 inch or it bogs. I suspect I am really lean now? Am I on the right track?
Back fire through carbs
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Jujuman
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Back fire through carbs
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Jujuman
67.5 SPL-311-13263
67.5 SPL-311-12442 no motor
69 SRL-311 2L/solex rust bucket.
2007 Expedition EL
Fayetteville NC
67.5 SPL-311-13263
67.5 SPL-311-12442 no motor
69 SRL-311 2L/solex rust bucket.
2007 Expedition EL
Fayetteville NC
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devo
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Re: Back fire through carbs
Sounds lean to me. I just went through this. Adjust the carbs 1/8 turn open on the adjusting nut, test run again, adjust again, etc. etc. etc, until smooth running at all speeds. You should only need the choke until engine is warmed up. If you have to use it to keep the car from bogging at speed, you are still too lean. Hope that helps.
EDIT: It looks like in your pics that you are using BP6ES plugs. With the EI Dizzy, you should be using BP6ES-11 plugs (or BPR6ES-11 resistor). They have a longer center probe to extend into the cylinder. They work much better with the EI system. Change those plugs to the -11's before adjusting carbs.
EDIT: It looks like in your pics that you are using BP6ES plugs. With the EI Dizzy, you should be using BP6ES-11 plugs (or BPR6ES-11 resistor). They have a longer center probe to extend into the cylinder. They work much better with the EI system. Change those plugs to the -11's before adjusting carbs.
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Jujuman
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Re: Back fire through carbs
any thoughts as to standard or "v-grove" spark plug?
both bpr6es-11(heat range 6) and zfr5f-11 (heat rang 5) are 19mm reach and 14mm thread
both bpr6es-11(heat range 6) and zfr5f-11 (heat rang 5) are 19mm reach and 14mm thread
Jujuman
67.5 SPL-311-13263
67.5 SPL-311-12442 no motor
69 SRL-311 2L/solex rust bucket.
2007 Expedition EL
Fayetteville NC
67.5 SPL-311-13263
67.5 SPL-311-12442 no motor
69 SRL-311 2L/solex rust bucket.
2007 Expedition EL
Fayetteville NC
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fj20spl311
- Roadsteraholic
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Re: Back fire through carbs
-11 plugs are too wide a gap unless you have an augmented ign. system. Reduce the gap to .028 to .032 at most.
Phil
67.5 SRL311-00148 Blue (FJ cruiser VOODOO Blue)
67.5 SPL311 FJ20E teal SDS EFI
69 SRL311 SOLD
19 Raptor SCAB
67.5 SRL311-00148 Blue (FJ cruiser VOODOO Blue)
67.5 SPL311 FJ20E teal SDS EFI
69 SRL311 SOLD
19 Raptor SCAB
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Jujuman
- Site Supporter
- Posts: 161
- Joined: Tue Sep 07, 2010 9:12 pm
- Location: Fayetteville NC
- Model: 1500/1600
- Year: Low Windshield-64-67.5
Re: Back fire through carbs
more confused now.
the tech wiki shows BP6ES with a .039-.042 gap
Devo reccomends BPR6ES-11
Phil reccomends BPR6ES-11 are too wide - shorten gap to .028-.032
I did notice better speed with the wider gap, still with questionable pre-ignition possibly from lean mix or heat (did run hotter with wider gap)
CHIVE references not withstanding
the tech wiki shows BP6ES with a .039-.042 gap
Devo reccomends BPR6ES-11
Phil reccomends BPR6ES-11 are too wide - shorten gap to .028-.032
I did notice better speed with the wider gap, still with questionable pre-ignition possibly from lean mix or heat (did run hotter with wider gap)
CHIVE references not withstanding
Jujuman
67.5 SPL-311-13263
67.5 SPL-311-12442 no motor
69 SRL-311 2L/solex rust bucket.
2007 Expedition EL
Fayetteville NC
67.5 SPL-311-13263
67.5 SPL-311-12442 no motor
69 SRL-311 2L/solex rust bucket.
2007 Expedition EL
Fayetteville NC
-
devo
- Roadsteraholic
- Posts: 536
- Joined: Mon Jun 17, 2013 7:58 pm
- Location: Texas
- Model: 1500/1600
- Year: Low Windshield-64-67.5
Re: Back fire through carbs
I am assuming, based on your first post that you have an EI dizzy.Jujuman wrote:any thoughts as to standard or "v-grove" spark plug?
both bpr6es-11(heat range 6) and zfr5f-11 (heat rang 5) are 19mm reach and 14mm thread
I just use the plugs that East Coast Roadster (The builder of my EI dizzy) recommends (BP6ES-11 or BPR6ES-11). He has them listed in his installation guide (page 11) on his website with gap at .039"-.043" if, the EI dizzy and the 12 volt coil are the only ignition system mods. The shorter core plugs will work, but did not work as well as the -11's he recommends, for my car anyway.