tapping/slapping noise

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Apr 12, 2008 | 10:39 PM

cruise83

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Joined: Aug 2007

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From: san antonio Texas

tapping/slapping noise

I have a tapping/slapping noise from the front of my 5.7L 350 in my 79. I have ruled out a valve tap for now. Can my timing chain be hitting its cover? If so can it be adjusted? Do the chains stretch over time a get loose? the noise apprears after 1500 RPM.

Apr 12, 2008 | 11:47 PM

PeteZO6

Drifting

Joined: Apr 2007

Posts: 1,970

Likes: 45

From: Cameron Park CA

The OEM sprocket on the cam had nylon teeth which can come off in chunks. If it does you will hear a ticking or clacking coming from that area. You can localize the noise by using a piece of hose or a long screwdriver and with one end near your ear, put the other on the timing cover. Be very careful around the fan!!!!!!

If that is the problem, a new timing set is in order. Best bet is a double row true roller.

Cheers,
Pete

Apr 13, 2008 | 01:33 AM

marshrat99

Melting Slicks

Joined: Aug 2003

Posts: 2,135

Likes: 2

From: Dayton Oh

Fig A for me would be the fuel pump believe it or not if you've not done anything recently to your engine.

Apr 13, 2008 | 08:22 AM

SIXFOOTER

Le Mans Master

Joined: Jan 2006

Posts: 9,192

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From: Boca Raton Florida

Check for exhaust leak before ripping the thing apart, will sound just like what you describe

Apr 13, 2008 | 10:48 AM

cruise83

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Instructor

Joined: Aug 2007

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From: san antonio Texas

thank you forum, now I have at least three trouble shooting tasks I can try. That's the fun of it, right...

Apr 13, 2008 | 10:55 AM

Ganey

Race Director

Joined: Apr 1999

Posts: 11,520

Likes: 13

From: CORVETTE 77 385 C.I. TEXAS

A worn fuel pump pushrod can make a tap like valve tap. Said to be "impossible" to find.

Apr 17, 2008 | 11:35 PM

cruise83

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Joined: Aug 2007

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From: san antonio Texas

problem solved by fuel pump

just want you to know I replaced the fuel pump and the noise went away. glad I did not tare into the timing chain and gear. Thanks forum.

Apr 18, 2008 | 03:55 PM

PeteZO6

Drifting

Joined: Apr 2007

Posts: 1,970

Likes: 45

From: Cameron Park CA

Quote:

Originally Posted by cruise83

glad I did not tare into the timing chain and gear. Thanks forum.

Me too! Always check the easiest first. I had the cam sprocket failure, but not the fuel pump push rod problem.

Cheers,
Pete

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Apr 18, 2008 | 11:47 PM

cruise83

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Instructor

Joined: Aug 2007

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From: san antonio Texas

one last issue a crimped furl line

see the picture, does anyone have pics about how to connect the fuel line to the pump?? Mine is crimping...

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Apr 18, 2008 | 11:51 PM

#10

cruise83

Thread Starter

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Joined: Aug 2007

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From: san antonio Texas

by the way, I needed to turn the ignition a couple of times to turn the cam shaft so the fuel pump rod could depress far enough to allow the fuel pump arm to insert into the proper position. Several of the books and manuals I had did not discuss this step. Using vaseline to hold the rod in place did help,