318 makes popping noise on number 1

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4spdDuster340

4spdDuster340

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I'm not very savoy with mopar engines. I have a Rebuilt 318 in a 74 duster. I'm not sure how many mile are on it as it was in the car when I bought it. It has a mild cam and a LD4B intake on it. It is otherwise stock as far as I know. It recently started making a popping noise in the number 1 cyl area. Sounds like a header gasket leak but I replaced the gasket (the old one showed no signs of a leak) and it still does it. The pop is inconsistant at idle but becomes regular and louder with rpm, especially when under load. I havent noticed any real lose of power. The car still chirps the tires in 2nd, 3rd and sometimes 4th just fine. Does sound like it might be missing a little after it warms up. What should I be looking at. All help is Appreciated.
 
Is it popping out the carb, or literally sound like and exhaust leak?
I have seen a headgasket blow without loosing coolant before (right out the side between the head and block.)

I use a small section of hose that I "sniff" out noises with, and it works pretty good for finding hard to find sounds.
 
Might be a leak around where the header pipe meets the flange , small hole , rust or broken weld , Check it out in the dark , see if any flame sparks are visible
 
mopar head said:
I`d pull the valve cover and make sure everything is kosher
might be a pushrod trying to find it`s way out.:happy1:
Click to expand...
Yes that'd be the 1st thing I done,check rocker arms and pushrods,could be a bent pushrod or a worn out rocker arm,or both, have seen pushrod stuck all the way thru a rocker before and still run fair but popping sound and was in a 318
 
I trust ,the o.p'sinstincts. Does it,get louder when you hit the throttle,under load?
 
Abodybomber said:
I trust ,the o.p'sinstincts. Does it,get louder when you hit the throttle,under load?
Click to expand...

"The pop is inconsistant at idle but becomes regular and louder with rpm, especially when under load."

In his post.:D
 
So I had some time today to mess with this thing. I pulled the plugs found a couple in not so good shape. Mainly to due to a predetination problem that it had when I bought it. which i corrected the day i brought it home. New plugs took care of the miss but not the pop. I pulled the valve cover and discovered that the intake lifter wasn't priming up. another thing to love about mopars, you can see the lifters through the head without pulling the intake manifold. Gonna put it back together tomorrow and see how it acts. Will update after that thanks for everyones help.
 
Samething happend to me a few years ago with a 350 chev. Ended up being a wipped out exhaust lobe on the cam.. It was poping out the carb.
 
Just a thought if he pull the plug wire off number one cylinder wouldn't the noise go away if it was a header leak? to rule it out.
 
If it is a regular pop through the intake and carb, look for something keeping the exhaust valve closed.
 
Possible plug wire cross fire?
Are your plug wires bunched together?
Are they in good condition?
 
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