How close to dead is it? - Team Camaro Tech
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post #1 of 9 (permalink) Old Jun 5th, 14, 11:48 AM Thread Starter
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Robert
 
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How close to dead is it?

I hear piston slap at start up AND anything over 2.5k rpm... That and my number 2 rocker keeps coming loose; or so I thought. After the second time I adjusted it, I scored the nut and the stud... It stayed in line but had a .02 gap after two weeks. Stupid tapping... Is my lifter is collapsing a lot or am I slowly sanding a lobe smooth? Push rod is straight btw. Thanks y'all!!!!

- Rob

1968, 5 speed, Vintage Air Gen IV, American Auto Wire Update Series, Champion 4 Core Rad, BMR front w/ Koni's, BP Roller 383, Posi 8.2", Solid Frame Bushings
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post #2 of 9 (permalink) Old Jun 5th, 14, 12:54 PM
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Scott
 
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Re: How close to dead is it?

How did you determine the noise is piston slap?

Does your engine have a flat tappet camshaft and lifters?

If so, you may be losing a lobe and/or a lifter based on your description.

How many miles on the engine, and the camshaft/lifters?

69 Camaro Z/28 RS, original Azure Turquoise, M21 & 3.73 12-bolt posi. NOM 406ci, AFR 210 heads, Straub hyd. roller cam & Dynatech 1-3/4" > 1-7/8" headers, QuickFuel 750 Annular. Photos at:
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post #3 of 9 (permalink) Old Jun 5th, 14, 02:19 PM Thread Starter
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Re: How close to dead is it?

Well, I say its slap because it sounds like a few old Chevys that I've heard right before the owners got the things bored and new pistons dropped in to eliminate the issue; successfully. Also, a mechanic friend of mine made some off hand comment about the lovely sounds that old Chevys make and he too said it sounded like slap. As for the cam, its a hydro flat that has a LOT of miles on it and is from a very old build. roughly 20k miles put on it since last February. Prior to that is unknown.
- Rob

1968, 5 speed, Vintage Air Gen IV, American Auto Wire Update Series, Champion 4 Core Rad, BMR front w/ Koni's, BP Roller 383, Posi 8.2", Solid Frame Bushings
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post #4 of 9 (permalink) Old Jun 5th, 14, 02:35 PM
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Re: How close to dead is it?

Pull the rocker, turn the engine by hand and measure (roughly) the pushrod movement. Should be on the order of .300" for a cam with .450" lift. (cam lift spec/1.5 rocker ratio)

Compare lift to another similar intake or exhaust pushrod and you will be able to tell if the lobe is gone.

'67 rs - ordered new by my Grandfather
327 L30, K-K, Deluxe int, tach & gauges, 12 bolt posi, 4 speed.

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post #5 of 9 (permalink) Old Jun 5th, 14, 04:24 PM Thread Starter
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Re: How close to dead is it?

That's a really good idea. I should have thought of that.... Dial indicator to the rescue! Mtf...
. - Rob

1968, 5 speed, Vintage Air Gen IV, American Auto Wire Update Series, Champion 4 Core Rad, BMR front w/ Koni's, BP Roller 383, Posi 8.2", Solid Frame Bushings
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post #6 of 9 (permalink) Old Jun 5th, 14, 09:50 PM
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Re: How close to dead is it?

Make sure that rocker stud isn't pulling out of the head.

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post #7 of 9 (permalink) Old Jun 6th, 14, 09:19 AM Thread Starter
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Re: How close to dead is it?

The stud is fine.... The lobe on the other hand... It's off by roughly 5 hundredths compared to the next two intake lobes. Oh well, drive it till she politely tells me to stop it. lol
- Rob

1968, 5 speed, Vintage Air Gen IV, American Auto Wire Update Series, Champion 4 Core Rad, BMR front w/ Koni's, BP Roller 383, Posi 8.2", Solid Frame Bushings
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post #8 of 9 (permalink) Old Jun 6th, 14, 12:58 PM
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Re: How close to dead is it?

Quote:
Originally Posted by rtchaney View Post
The stud is fine.... The lobe on the other hand... It's off by roughly 5 hundredths compared to the next two intake lobes. Oh well, drive it till she politely tells me to stop it. lol
- Rob
Looks like you are facing the decision of what cam to try next.

'67 rs - ordered new by my Grandfather
327 L30, K-K, Deluxe int, tach & gauges, 12 bolt posi, 4 speed.

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post #9 of 9 (permalink) Old Jun 6th, 14, 02:13 PM Thread Starter
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Re: How close to dead is it?

Now to convince my wife that an LS1 is cheaper in the long run.
- Rob

1968, 5 speed, Vintage Air Gen IV, American Auto Wire Update Series, Champion 4 Core Rad, BMR front w/ Koni's, BP Roller 383, Posi 8.2", Solid Frame Bushings
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