<VV> Follow Up: "Possible piston slap"

Sat Nov 2 11:18:49 EDT 2019

Follow-up to Replys: 

1) "... Lifters a CLACKs!  Piston Slap is ?tonk?..."  MM: Not lifter noise; have new lifters + roller rocker arms; all adjusted while running; noise is deeper and of a lower "note" than rocker/lifter noise.

2)  "... Would be nice if there was a recording of the sound posted..." MM: Will try to capture and post up. 

3) "... I had a crazy issue a few years ago with brand new pistons . They were supposed to be .060 (factory marked !) but were actually .030 measured..." MM: TRW forged pistons; all clearances             measured up fine during assembly. 
With original post, I was hoping to hear of someone, specifically a Corvair rebuild using forged pistons, where cold-startup piston slap was found. Searching the internet, I find forged pistons "grow" larger than cast, when warmed; for that reason initial piston-to-cylinder clearances are intentionally made greater (than with cast pistons), sometimes leading to cold slap noise.   "My" noise goes away, ENTIRELY, when engine warms. It's not lifter clatter (having owned Corvairs since 1970, I've heard and corrected my fair share of lifter issues). If its just piston slap, I'll let it ride... I will, however, (as suggested in a later post)  try pulling individual plug wires to isolate the offending cylinder.  Thanks to all for the help... Mike Mauro   

-----Original Message-----
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To: virtualvairs <virtualvairs at corvair.org>
Sent: Fri, Nov 1, 2019 9:39 pm
Subject: VirtualVairs Digest, Vol 178, Issue 2

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Today's Topics:

  1. Possible piston slap. (Jerry Brown)
  2. Re: Possible piston slap. (Hugo Miller)
  3. Re: Possible piston slap. (Matt )
  4. Re: Possible piston slap. (Marc Sheridan)
  5. Re: Bizzare  piston slap memories (N2VZD TIM)
  6. Re: Possible piston slap. (Hugo Miller)
  7. Re: Bizzare  piston slap memories (Hugo Miller)
  8. Re: Bizzare piston slap memories (Michael)

----------------------------------------------------------------------

Message: 1
Date: Fri, 1 Nov 2019 17:01:37 +0000 (UTC)
From: Jerry Brown <air_cooled63 at yahoo.com>
To: "virtualvairs at corvair.org" <virtualvairs at corvair.org>
Subject: <VV> Possible piston slap.
Message-ID: <2018846067.357837.1572627697469 at mail.yahoo.com>
Content-Type: text/plain; charset=UTF-8

Yes it sounds like a piston slap.? I had a similar problem, but only one piston slap.? When the engine was assembled a worn cylinder got mixed in with the non worn cylinders that was worn to 12.5 thousands.? 5 thousands is the limit.? If you take the spark plug wire off one at a time? while running cold and slap sound goes away then you have piston slap.? ?If it still knocks it's most? probably bad crankshaft.??
Jerry

Sent from Yahoo Mail on Android

------------------------------

Message: 2
Date: Fri, 01 Nov 2019 22:35:56 +0100
From: Hugo Miller <hugo at aruncoaches.co.uk>
To: <virtualvairs at corvair.org>
Subject: Re: <VV> Possible piston slap.
Message-ID: <049bac6bdb9e939198ba9c04f692bb2d at aruncoaches.co.uk>
Content-Type: text/plain; charset=UTF-8; format=flowed

Why am I the only person who has mentioned valve lifters as a possible 
cause? I am probably inviting some rude answers, I know ;)

On 2019-11-01 18:01, Jerry Brown via VirtualVairs wrote:
> Yes it sounds like a piston slap.? I had a similar problem, but only
> one piston slap.? When the engine was assembled a worn cylinder got
> mixed in with the non worn cylinders that was worn to 12.5 
> thousands.?
> 5 thousands is the limit.? If you take the spark plug wire off one at
> a time? while running cold and slap sound goes away then you have
> piston slap.? ?If it still knocks it's most? probably bad
> crankshaft.??
> Jerry
>
> Sent from Yahoo Mail on Android
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------------------------------

Message: 3
Date: Fri, 1 Nov 2019 16:39:04 -0700
From: "Matt " <patiomatt at aol.com>
To: "virtualvairs at corvair.org" <virtualvairs at corvair.org>
Subject: Re: <VV> Possible piston slap.
Message-ID: <mailman.120.1572651555.1356.virtualvairs at corvair.org>
Content-Type: text/plain; charset="utf-8"

Lifters a CLACKs!  Piston Slap is ?tonk?

From: Hugo Miller via VirtualVairs

Why am I the only person who has mentioned valve lifters as a possible 
cause? I am probably inviting some rude answers, I know ;)

------------------------------

Message: 4
Date: Fri, 1 Nov 2019 19:43:14 -0400
From: Marc Sheridan <sheridanma1966 at gmail.com>
Cc: "virtualvairs at corvair.org" <virtualvairs at corvair.org>
Subject: Re: <VV> Possible piston slap.
Message-ID:
    <CABXqKfbishVXbPkeMcv9kVYkAju6S4FnW=0NCV0uiXmAZyBWDA at mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"

Would be nice if there was a recording of the sound posted.

On Fri, Nov 1, 2019 at 7:39 PM Matt via VirtualVairs <
virtualvairs at corvair.org> wrote:

> Lifters a CLACKs!  Piston Slap is ?tonk?
>
>
> From: Hugo Miller via VirtualVairs
>
> Why am I the only person who has mentioned valve lifters as a possible
> cause? I am probably inviting some rude answers, I know ;)
>
>  _______________________________________________
> This message was sent by the VirtualVairs mailing list, all copyrights are
> the property
> of the writer, please attribute properly. For help, mailto:
> vv-help at corvair.org
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> http://www.corvair.org/
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>  _______________________________________________
>

------------------------------

Message: 5
Date: Sat, 2 Nov 2019 00:17:52 +0000 (UTC)
From: N2VZD TIM <n2vzd at aol.com>
To: virtualvairs at corvair.org
Subject: Re: <VV> Bizzare  piston slap memories
Message-ID: <250125214.48711.1572653872913 at mail.yahoo.com>
Content-Type: text/plain; charset=UTF-8

I had a crazy issue a few years ago with brand new pistons . They were supposed to be .060 (factory marked !) but were actually .030 measured . This was after going nuts with the sounds. The compression was "OK" but the noise was almost like lifter noise or oil pressure problem , but gauge showed good pressure. I will never buy parts like that from anywhere but my trusted source. These were new parts in the boxes from a private vendor at the Sturbridge .He probably had no idea , because they were NOS not? properly marked in correct boxes? (they said .060 on top but measured .030 at the shop.? ?Very strange noise!? I never had to check measurements before !Regards, Tim Colson

------------------------------

Message: 6
Date: Sat, 02 Nov 2019 02:01:46 +0100
From: Hugo Miller <hugo at aruncoaches.co.uk>
To: <virtualvairs at corvair.org>
Subject: Re: <VV> Possible piston slap.
Message-ID: <0b45ca98ab9ffcf0d89cd2fa89f0423d at aruncoaches.co.uk>
Content-Type: text/plain; charset=UTF-8; format=flowed

I thought he described it as a 'knock'? The easy way to tell, rather 
than having us all doing sound effects like Victor Borge, is to observe 
whether it only occurs under load when cold, or at all times, until the 
oil gets circulated and the lifters pump up anyway.

On 2019-11-02 00:39, Matt via VirtualVairs wrote:
> Lifters a CLACKs!  Piston Slap is ?tonk?
>
>
> From: Hugo Miller via VirtualVairs
>
> Why am I the only person who has mentioned valve lifters as a 
> possible
> cause? I am probably inviting some rude answers, I know ;)
>
>  _______________________________________________
> This message was sent by the VirtualVairs mailing list, all
> copyrights are the property
> of the writer, please attribute properly. For help,
> mailto:vv-help at corvair.org
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> http://www.corvair.org/
> Post messages to: VirtualVairs at corvair.org
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>  _______________________________________________

------------------------------

Message: 7
Date: Sat, 02 Nov 2019 02:06:30 +0100
From: Hugo Miller <hugo at aruncoaches.co.uk>
To: <virtualvairs at corvair.org>
Subject: Re: <VV> Bizzare  piston slap memories
Message-ID: <2061bbe32826efd4bc083dddf14c9fb0 at aruncoaches.co.uk>
Content-Type: text/plain; charset=UTF-8; format=flowed

Never take anything for granted! I once assembled a Bristol 2 litre  
six cylinder engine. After I fitted the pistons, I had a piston pin 
circlip (snap ring) left over. I was certain I couldn't have forgotten 
to put one in somewhere, but of course I had to take the whole damn lot 
out to verify. Since then, I always COUNT the snap rings before 
assembly!

On 2019-11-02 01:17, N2VZD TIM via VirtualVairs wrote:
> I had a crazy issue a few years ago with brand new pistons . They
> were supposed to be .060 (factory marked !) but were actually .030
> measured . This was after going nuts with the sounds. The compression
> was "OK" but the noise was almost like lifter noise or oil pressure
> problem , but gauge showed good pressure. I will never buy parts like
> that from anywhere but my trusted source. These were new parts in the
> boxes from a private vendor at the Sturbridge .He probably had no 
> idea
> , because they were NOS not? properly marked in correct boxes? (they
> said .060 on top but measured .030 at the shop.? ?Very strange 
> noise!?
> I never had to check measurements before !Regards, Tim Colson
>
>
>  _______________________________________________
> This message was sent by the VirtualVairs mailing list, all
> copyrights are the property
> of the writer, please attribute properly. For help,
> mailto:vv-help at corvair.org
> This list sponsored by the Corvair Society of America,
> http://www.corvair.org/
> Post messages to: VirtualVairs at corvair.org
> Change your options: 
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>  _______________________________________________

------------------------------

Message: 8
Date: Sat, 02 Nov 2019 01:39:23 +0000
From: Michael <mmccrae6 at cox.net>
To: hugo at aruncoaches.co.uk, virtualvairs at corvair.org
Subject: Re: <VV> Bizzare piston slap memories
Message-ID: <em4a938ed5-73f1-42b8-8e5e-0a45a34f6ab1 at michael-pc>
Content-Type: text/plain; format=flowed; charset=utf-8

I bought several sets of "forged" pistons from a vendor several years 
ago....since I always had the cylinders bored to the piston, the machine 
shop
caught the fact that they were marked .040 but were really .030.... 
Never, ever buy pistons separately from the cylinders and expect them to 
work.
Always hand the cylinders to the machinist and have them bored to the 
cylinders that he can measure in shop.

Mike McCrae

------ Original Message ------
From: "Hugo Miller via VirtualVairs" <virtualvairs at corvair.org>
To: virtualvairs at corvair.org
Sent: 11/1/2019 6:06:30 PM
Subject: Re: <VV> Bizzare piston slap memories

>Never take anything for granted! I once assembled a Bristol 2 litre  six cylinder engine. After I fitted the pistons, I had a piston pin circlip (snap ring) left over. I was certain I couldn't have forgotten to put one in somewhere, but of course I had to take the whole damn lot out to verify. Since then, I always COUNT the snap rings before assembly!
>
>On 2019-11-02 01:17, N2VZD TIM via VirtualVairs wrote:
>>I had a crazy issue a few years ago with brand new pistons . They
>>were supposed to be .060 (factory marked !) but were actually .030
>>measured . This was after going nuts with the sounds. The compression
>>was "OK" but the noise was almost like lifter noise or oil pressure
>>problem , but gauge showed good pressure. I will never buy parts like
>>that from anywhere but my trusted source. These were new parts in the
>>boxes from a private vendor at the Sturbridge .He probably had no idea
>>, because they were NOS not  properly marked in correct boxes  (they
>>said .060 on top but measured .030 at the shop.  Very strange noise!
>>I never had to check measurements before !Regards, Tim Colson
>>
>>
>>  _______________________________________________
>>This message was sent by the VirtualVairs mailing list, all
>>copyrights are the property
>>of the writer, please attribute properly. For help,
>>mailto:vv-help at corvair.org
>>This list sponsored by the Corvair Society of America,
>>http://www.corvair.org/
>>Post messages to: VirtualVairs at corvair.org
>>Change your options: http://www.vv.corvair.org/mailman/options/virtualvairs
>>Archives: http://www.vv.corvair.org/archive.htm
>>  _______________________________________________
>
>_______________________________________________
>This message was sent by the VirtualVairs mailing list, all copyrights are the property
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