egr or timing backfire

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Casca 2525

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I have a 360 that is in a 79 coachman, not sure what year the 360 is just know its not the original, its backfiring about a 6" to 1' flame out the left front of the tq, is it an egr or carb/timing issue, I ask due to the fact the egr passage is directly beneath that barrel
 
Could be a wiped cam, cracked dist cap , A cold engine with out a working choke, dist loose , ect,ect .
 
Mopars dont have a common history of EGR grief like the fords.
It's more likely a crossed plug wire, bent pushrod, or pushrod thru rocker, cracked cap, or as mentioned above.
Post a video .
 
Either is possible. But you’ll get a bigger fireball with a bad intake valve.
 
Not sure how you'd measure it, I know both will remove your eye-brows, both will ignite the intake manifold, lol .
 
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TT5.9mag said:
Either is possible. But you’ll get a bigger fireball with a bad intake valve.
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Intakes are pretty safe, seldom burn, I've found that a missed shift, with or without a weak spring, the ex valve can be "spanked" by the piston, and/or bend the pushrod, and poke it thru the rocker, leaving a witness mark on the piston.
Often, no valve damage occurs, just lose a cyl, and get a mean backfire, same as losing a lobe.
I used to carry spares in my glove box, right beside a spare ballast.
Cheers .
 
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I’m familiar, unfortunately.
:rofl:
 
teringer said:
Could be a wiped cam, cracked dist cap , A cold engine with out a working choke, dist loose , ect,ect .
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cap, rotor and wires are all new so hoping I don't need to rma them, and no, I changed them after the backfire that deafened us and got rid my pesky hair, in an effort to solve the problem, and they made no difference
 
Good answer, look at your spark plugs, they will likely show which cyl. One will be different. If they're a *****, I'd pull valve covers .
 
Air cleaner OFF. Put it in D with foot on the brake and slowly open the throttle. If the pop is repetitious, as in EVERY time that cylinder fires, you have something keeping an exhaust valve closed. That cylinder will still fire, but it sends the exhaust back up through the intake. If that's what it does, look for things like bent pushrod, bad rocker arm, or unfortunately wiped cam lobe. This will NOT show up on a compression test, so don't even think about it. Just use my diagnosis as outlined.
 
we are curretly taking offers of a ride to Hamilton to pick up an aluminum intake, figure since it looks like I'm going in deep, may as well go with an egr free intake
 
RustyRatRod said:
Air cleaner OFF. Put it in D with foot on the brake and slowly open the throttle. If the pop is repetitious, as in EVERY time that cylinder fires, you have something keeping an exhaust valve closed. That cylinder will still fire, but it sends the exhaust back up through the intake. If that's what it does, look for things like bent pushrod, bad rocker arm, or unfortunately wiped cam lobe. This will NOT show up on a compression test, so don't even think about it. Just use my diagnosis as outlined.
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air cleaner was off which is how I burnt off arm hair, eyelashes eyebrows, and some up top, which bothers me more than anything else, I am running short of it, and i was trying to get it to move under power, but when it backfires it blows its self out
 
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Casca 2525 said:
air cleaner was off which is how I burnt off arm hair, eyelashes eyebrows, and some up top, which bothers me more than anything else, I am running short of it, and i was trying to get it to move under power, but when it backfires it blows its self out
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Ok, follow the rest of the diagnosis procedure and you can either confirm or eliminate. OR you can just keep working blindly.
 
I am thankful for the time and effort you put in your message, for now this is on hold whilel I scrape together cash to buy a car, I really do appreciate your time I had planned to juggle both,
but based on what you've told me I'm look at a lot more serious issues than I can effectively deal with as I cant keep it running long enough to tell if the If the pop is repetitious, as in EVERY time that cylinder fires, because as soon as I put it in gear it back fires an dies
 
Pull one spark plug wire off at a time and start it. When the popping stops you found the problem cylinder. Don’t give up yet it could be something really simple. I’ve straightened bent pushrods on flat concrete with a hammer to get running again.
 
Have you drastically increased the setting of the speed screw?
This usually points to retarded timing and often that is because the cam has gone retarded.
The quick test is to just pull in some timing and if it stops doing that, then put the speed screw back. Now you can check the ignition-timing and if it is seriously advanced then you go check the cam-timing.

But if it's only blasting fire out of one side of a dual plane, then you know where to look, namely one cylinder on that half of the intake, has a problem. Isolation, as mentioned is by removal of one hi-tension secondary wire atta time.
 
teringer said:
Could be a wiped cam, cracked dist cap , A cold engine with out a working choke, dist loose , ect,ect .
Click to expand...

AJ/FormS said:
Have you drastically increased the setting of the speed screw?
This usually points to retarded timing and often that is because the cam has gone retarded.
The quick test is to just pull in some timing and if it stops doing that, then put the speed screw back. Now you can check the ignition-timing and if it is seriously advanced then you go check the cam-timing.

But if it's only blasting fire out of one side of a dual plane, then you know where to look, namely one cylinder on that half of the intake, has a problem. Isolation, as mentioned is by removal of one hi-tension secondary wire atta time.
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Ok, I was wondering about that, it's been a lot of years since I laid hands on a gas v8 or even a v6 that has a distributorso I am second guessing myself a lot
 
So 10 days and 25 posts and not one single picture provided. THAT'S the rabbit hole. I'm done here.
 
RustyRatRod said:
So 10 days and 25 posts and not one single picture provided. THAT'S the rabbit hole. I'm done here.
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sorry, pictures aren't something I give much thought to, I don't carry a phone and I never think of my camera till after its to late to grab, and when I'm around family, some one always has a phone or DSLR out snapping away so I just get them sent to me.
 
here she is, my exs boyfreind decided the carb was toast from all the flames, so he pulled it, got it apart and unable finish, I got it back, ordered a kit and down loaded a repair manual for a thermoquad, one thing that doesn't appear in the stuff I have read tell to remove the plates, is that some I should do? or leave them alone an clean what l can with them in place

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