Need help - Chevelle Tech
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post #1 of 16 (permalink) Old Mar 10th, 20, 1:34 PM Thread Starter
 
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Need help

I have a '72 Chevelle 396 w/ an HEI distributor. I am not an engine guy by any means and usually have my Dad walk me through these issues (died 3 years ago). About 3 months ago I tuned up (timing and carb adjustments) my 396 and everything was running fine except sputter and backfire (in the exhaust) when romping on her at about 40mph... which when she's coldish that's the norm. Recently, I went to fire her back up and she acted like she was only firing on 2-4 cylinders. Pulled plugs, replaced cap and rotor (placed the plug wires in the exact same order they came off), plug wires are in good shape, compression checked each cylinder (all good to go). My question is, should I be looking at a new coil and ignition module? What would cause a normal running engine to start running like an air pump? Any help is appreciated.
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post #2 of 16 (permalink) Old Mar 10th, 20, 3:05 PM
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Rick
 
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Re: Need help

What did the plugs look like internally? Rich running? Sooty, black or wet? If yes, you might have fouled your spark plugs.

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post #3 of 16 (permalink) Old Mar 10th, 20, 3:08 PM Thread Starter
 
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Re: Need help

They did in fact look sooty and a little wet, but I cleaned them up with carb cleaner and a wire brush and retried starting the motor with the same result.
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post #4 of 16 (permalink) Old Mar 10th, 20, 4:05 PM
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Rick
 
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Re: Need help

Once a plug gets wet and cooled in fuel, quite often it can't be cleaned up. I'd put a new set of plugs in and see what happens.

I'm also thinking bad gas. I only use fuel without ethanol.

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post #5 of 16 (permalink) Old Mar 13th, 20, 7:02 PM Thread Starter
 
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Re: Need help

Rick, thanks for the help... that was what the doctor ordered!!!!
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post #6 of 16 (permalink) Old Mar 13th, 20, 7:19 PM
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Re: Need help

I have been running the non-ethanol 92 octane fuel too. Very expensive however.

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post #7 of 16 (permalink) Old Mar 13th, 20, 7:39 PM Thread Starter
 
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It's hard to find non-ethanol mixed gas... can you suggest an additive to help combat the effects of ethanol mixed fuel?
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post #8 of 16 (permalink) Old Mar 13th, 20, 8:03 PM
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It's hard to find non-ethanol mixed gas... can you suggest an additive to help combat the effects of ethanol mixed fuel?
There isn’t such an additive that I know of. If you live near a large body of water, boat marinas often carry non-corn gas

Good luck!
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post #9 of 16 (permalink) Old Mar 13th, 20, 8:21 PM Thread Starter
 
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Unfortunately no I don't... but thanks for the insight
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post #10 of 16 (permalink) Old Mar 13th, 20, 8:24 PM
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Re: Need help

In our area they call it Rec Fuel (as in recreation). Snowmobilers and boaters mainly use it, also is all I will use in my snowblower and lawnmower not to mention my classic vehicles.
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post #11 of 16 (permalink) Old Mar 13th, 20, 8:44 PM Thread Starter
 
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I'm in Wichita... I could imagine that there are places like that around here but I have yet to find them... only been here for 6 months
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post #12 of 16 (permalink) Old Mar 13th, 20, 11:22 PM
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Re: Need help

Sta-bil makes an additive for combating ethanol gas, should be in any parts store chain. good luck!!

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post #13 of 16 (permalink) Old Mar 14th, 20, 1:15 AM
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Re: Need help

Quote:
Originally Posted by BCarter72 View Post
It's hard to find non-ethanol mixed gas... can you suggest an additive to help combat the effects of ethanol mixed fuel?
Yes there is
While I am not a fan of additives this stuff actually works

Star Tron Enzyme Fuel Treatment Gas Additive Shooter
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post #14 of 16 (permalink) Old Mar 14th, 20, 1:18 AM
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Re: Need help

If you have a small airport near you, see if you can buy av-gas there. Great stuff, but some places are snippy about selling it to car guys.
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post #15 of 16 (permalink) Old Mar 14th, 20, 9:36 AM
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Re: Need help

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Originally Posted by BCarter72 View Post
I'm in Wichita... I could imagine that there are places like that around here but I have yet to find them... only been here for 6 months
https://www.pure-gas.org/index.jsp?stateprov=KS
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