spark plug reading

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arlancam509
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spark plug reading

Post by arlancam509 »

Trying to get my 11.2:1 aircooled engine to run and am hoping to get some opinions on what this spark plug shows. The engine will fire as i am cranking and sound like it doesn't have enough timing to keep it going (it just speeds up the starter). But every other rotation of the engine, it will buck against the starter like it has too much advance. The temperature in my barn is 60° and i am running e85 (much closer to e50 right now). I have a brand-new fuel-injection build and there are just so many variables... sheesh. i have been reading and studying for the last 5 years so i would be ready for this day. i got the engine to run for 2 minutes a few nights ago. It wouldn't idle, but it would rev pretty cleanly up to my self-imposed rev limit of 3000rpm. I pulled those spark plugs and they're almost black, but not sooty. Almost seemed a little wet, but with the e85, i think it might have been water.

The spark plug in this picture has about 30 seconds of "run-time" with the starter keeping the engine turning over. My burning eyes are telling me it is rich. I should trust my gut, but i can't help doubting myself. I am a little afraid of making it too lean, but i suppose i could do it as a quick test. Yes, i have a wideband, but i am not sure i trust it until the engine is actually running off of the starter.

summary: engine cranks and fires and will continue to fire as long as i stay on the starter. every other rotation, it bucks back against the starter. if you have gotten this far, i applaud you. if no one replies, i will understand. i wouldn't reply to this. haha! :lol:
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jed
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Re: spark plug reading

Post by jed »

Can you give us more information on the air cooled engine, the application, mechanical or electrical injection and ignition. Is it a flat head, OHV, or a OHC. Need more info
ProPower engines
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Re: spark plug reading

Post by ProPower engines »

Sounds like a case of too much fuel and wrong ignition advance.
e85 can also have too much alky for your carb if thats what is used and need more gas added to get it to run right.
We played with e85 and a 2bbl rochester with corrected jetting and we settled on 36% gas/akly mix and it was perfect.
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arlancam509
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Re: spark plug reading

Post by arlancam509 »

ProPower engines wrote: Thu Nov 05, 2020 6:43 pm Sounds like a case of too much fuel and wrong ignition advance.
e85 can also have too much alky for your carb if thats what is used and need more gas added to get it to run right.
We played with e85 and a 2bbl rochester with corrected jetting and we settled on 36% gas/akly mix and it was perfect.
with my wife's help, she told me to stop over-thinking it and get back to basics, i was able to get this figured out. too much fuel and too much ignition advance - about 40° worth! :D
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arlancam509
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Re: spark plug reading

Post by arlancam509 »

jed wrote: Thu Nov 05, 2020 6:24 pm Can you give us more information on the air cooled engine, the application, mechanical or electrical injection and ignition. Is it a flat head, OHV, or a OHC. Need more info
aircooled volkswagen
aftermarket case and heads, h-beam rods, stroker crank, full-race cam (or is it 3/4?), custom intake fab'd by me, 1-5/8 header (also mine), megasquirt ECU with sequential spark and fuel.

the gory details:
3.70 bore x 3.30 stroke
heads - 1.81 intake x 1.47 exhaust (1.81 x 1.47)
cam: .547 lift / 258° @ .050
11.2:1 compression
e85

here is a video i made right after i got this thing running with the (mostly) correct timing and still have plenty of fuel work to obviously:
https://youtu.be/Rb245eUgat4

i really can't believe this thing actually runs. i've been playing with cars for 31 years and this is my first dive into fuel injection. it is a whole 'nother world. i am so happy and really needed a win this year. :wink:
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jed
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Re: spark plug reading

Post by jed »

Good for you for getting it running. From the video there needs to be some more tuning. Let us know how that full race cam works out. lol
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