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I have a 69 Mach 1, 351C, 2BBL Heads, FMX, 3.25 rear end. I have an annoying ticking sound that occurs most between 25 - 45 mph in D (no tach) and decelarating. It seems to go away under acceleration and under or over those speeds. I'm guessing its a valve or lifter. Can you give me any tips on how to find which one, and then how do I fix it?

351C is bored .030, Edelbrock manifold, Holley carb, headers.

I'm finally driving the car regularly after having it sit for 12 years being driven 3-4 times a year and having it spend the last 3 years at the body shop. I put new exhaust on it Friday and the ticking is really annoying now.
 

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If it is a tick, and not a header leak, it sounds like a rod tap...doesnt sound like the lifters to me because it only happens when the lower end is under very light loads.

The primary causes if it is rod tap is excessive rod bearing clearances due to worn bearings (most likely) or stretched rods, though excessive ignition advance, particularly vacuum advance can (in VERY severe cases) cause it.

Try disconnecting the vacuum advance and drive it....if it goes away, I bet it is rod tap.

BTW, this shouldnt be mistaken for pinging...if you dont know what pinging sounds like, find someone local who does.
 

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Pick up a Stethascope (SP) at the local auto parts store. With the metal tip off (just the tube) go around each exhaust port and check for leaks. If no leaks put the tip on and press it aginst various spots on your engine. Rocker covers, oil pan, Intake manifold. See it you can pinpoint the ticking.
By bet is a simple exhaust leak
 

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I remember an old post here to look for an enhaust leak by pouring a bit of transmission fluid in the carburetor to make your car smoke and watch for smoke leaking out of the exhaust system.

The stethiscope is the tool you need. In addition to all the other places listed to listen to add the fuel pump. Thats where my car ticks from.
 

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First, try duplicating the noise with the car stationary and the trans in park

Then, run the car on stands and attempt to duplicate the noise with the wheels turning...you can load them for short periods of time with the service brakes to duplicate road loads...

Use the stethoscope as recommended by others.

Get back to us..
 
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