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Is this sound normal?
#1
Hi there all,
I’ve slowly been getting things improved on the Mach 1. It has 351c 4 V. I recently had brand new custom headers and exhaust installed, new push rods and gauge plates. It has a solid cam and solid lifters and my mechanic assures me he has the lash set correctly and that this “sewing machine “ sound is normal. He’s a bit deaf though. What do you think? Is the tapping sound normal? Thanks. Adam

https://youtu.be/p1-7N4FDf1o


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#2
(04-06-2019, 05:48 PM)adam.stevenson Wrote: Hi there all,
I’ve slowly been getting things improved on the Mach 1. It has 351c 4 V.  I recently had brand new custom headers and exhaust installed, new push rods and gauge plates. It has a solid cam and solid lifters and my mechanic assures me he has the lash set correctly and that this “sewing machine “ sound is normal. He’s a bit deaf though.  What do you think? Is the tapping sound normal?  Thanks. Adam

https://youtu.be/p1-7N4FDf1o


Sent from my iPad using Tapatalk

I'd wait for the experts to reply, but it sounds like a header gasket leak from here
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#3
I am NO expert by a long shot, but to me I think I'd agree with JohnnyJ, massive exhaust leak.
If not that, then perhaps your mechanic dropped a bucket of bolts inside! I can't imagine the valves been set that far off to rattle like that, but anything is possible.
I used to own a 72 Q code, but the block was Boss 351 ( I didn't find that little nugget until many years after I sold the car) but I did know it had solid lifters and that was about all I knew at the time, 1980.
What I'm getting at is it never sounded like that, not even cold. Something is wrong for sure. Was the motor broken in properly with a very good break-in oil? It might have wiped the cam out already if not. I would run it any more until you know what the heck is going on.

Geoff.

I learn something new every day!
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#4
It sounds like a lawn mower. Could be the lash but there are others here with more experience.

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        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
4-wheel disc brakes
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#5
Hard to say on this recording,
Based on sound, I would tend to think its a leaky exhaust gasket above an head gasket first.
Not saying for sure it's not, but the engine turns too nicely for a blown head gasket.
Also when they blow on Cleveland's, you often have coolant leaks when that happens.

Check fluids level to be sure. Also you could lift a valve cover..

73 modified Grandé 351C. Almost done. 
71 429CJ. In progress
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#6
Ok thanks everyone. I’ll take it to another mechanic. I only just (last week) had an entirely new custom made set of headers put on so I assumed it wouldn’t be an exhaust leak. The last set of headers definitely leaked. Should I take it back to the exhaust shop? My assumption is they would have hooked the new headers all up correctly and eliminated any exhaust leak - especially with the price I paid.
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#7
When the engine is right there should be no sound the is not is harmonics. I sounds like something it off.


When a man is in the woods and talks and no women are there is he still wrong??
Tongue
David
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#8
Solid lifters will definitely make some noise, a light clatter. Most video cameras, and all cell phones, have compression/amplification (compander) circuitry in the microphones, which amplifies sounds to a level that can be heard during playback, so it's hard to tell just how loud it is.

However, I believe we're hearing both valve noise and an exhaust leak, or one really loud valve on the driver side.

Take a short section of copper or steel tubing with a piece of rubber hose connected to it (a homemade mechanics stethoscope), hold the rubber hose to your ear and run the metal tube along the header connections and you'll be able to hear where the exhaust leak is.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#9
I'm going to agree with the guys above, something isn't right and it's hard to tell with a cell phone audio. I can easily tell the difference between an exhaust leak and valvetrain noise in person.

If it's a header collector to h-pipe gasket leak, the noise will be under the car. A header to head gasket leak will usually make a "popping" noise and get much louder if you rev the engine, or put it under load. If the volume of the noise doesn't increase, it's probably valvetrain.

At that point, I'd pull the valve covers and check the rockers for one adjusted out of spec.


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#10
Hi everyone. Thanks so far. A quick update. Went back to the exhaust shop. Definitely not leak. So I dropped into an old school mechanic around the corner and he will look at it properly in a couple of weeks as he is too busy this week but he thinks it’s rear passenger side lifter or rocker. Will let you know in a couple of weeks. I’m not much of a mechanic and never lifted valve covers myself so probably should just the experts to do it.
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