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Author
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Topic: Cleveland Piston Slap
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perk
Gearhead Posts: 328
From: Staley,nc
Registered: Sep 2000
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posted 05-08-2001 09:22 PM
   
New topic,but it ties in somewhat to my
total advance post.
What is piston slap? What causes this ?
I posted last year about a noise that came in around 3000 rpm while driving.Well now it comes in at around 2300. Someone told me this was piston slap and it only happens while giving it gas.
Is this bad for the engine?? I've heard that
clevelands were bad for this.
Any suggestions or info,,,,,thanksperk
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Moneymaker
Administrator Posts: 12790
From: Lyons, IL, USA
Registered: May 99
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posted 05-08-2001 09:36 PM
Piston slap is caused by a piston that is too loose in the bore. Either the bore is too big or the skirt of the piston has worn or began to cave in.  ------------------
Alex Denysenko Co-Administrator and Moderator NHRA/IHRA/SRA member
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link
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Nos351C
Gearhead Posts: 3000
From: Rohnert Park, CA USA M&M member#591
Registered: Jul 2000
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posted 05-09-2001 01:58 AM
Didn't ford have problems with the factory boss 302 piston skirts collapsing under hard use?------------------
Marcus
Warsteiner- Because Life is too short to drink cheap beer!
"You just got passed by a GIRL!" -A.J. Foyt
My World
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Mike_R
Gearhead Posts: 102
From: Indianapolis, IN 46237
Registered: Feb 2001
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posted 05-09-2001 01:01 PM
I hate to ask this because it's going to sound like the obvious, but could this be predetonation (spark knock). My brother's 428 used to spark knock so bad when he gave it the gas it sounded like the piston was going to was going to rock it's way right through the cylinder wall.The main reason I ask this is because like I mentioned in a previous post I accidently wound up with my duraspark distributor having 54 degrees of advance and I know you've been trying to sort your distributor out too.
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SteveLaRiviere
Administrator Posts: 23693
From: Saco, Maine USA
Registered: May 99
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posted 05-09-2001 07:08 PM
You hear piston slap when the engine is cold, before the pistons have a chance to expand to the proper clearance.What you have sounds exactly like detonation. ------------------
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC {Wife's car...}
All Fords since 1977 [This message has been edited by SteveLaRiviere (edited 05-09-2001).]
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perk
Gearhead Posts: 328
From: Staley,nc
Registered: Sep 2000
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posted 05-09-2001 07:46 PM
Ok,if it's detonation,what can I do about this?? I've tried 110,93,89,and 87 octane gas
and it does this with all types. 110 was the
worse.
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Moneymaker
Administrator Posts: 12790
From: Lyons, IL, USA
Registered: May 99
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posted 05-09-2001 08:51 PM
You should never get close to detonation with 110 octane fuel unless you are WAY lean and/or have ablout 80 degrees of total timing perk. ------------------
Alex Denysenko Co-Administrator and Moderator NHRA/IHRA/SRA member
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link
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perk
Gearhead Posts: 328
From: Staley,nc
Registered: Sep 2000
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posted 05-09-2001 09:29 PM
Ok,when I ran out of gas at the track last year,we put 3gal. in and what ever this noise
is,it was louder and when we put in the 87,
it became less,but still there.
The engine is running great except for what ever this noise is.  
perk
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jkilroy
Gearhead Posts: 1504
From: Vicksburg, MS
Registered: Dec 99
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posted 05-09-2001 09:45 PM
Get out the timing light and check the initial and total advance, thats first.Then pull the plugs and get a read, better yet take a clear digital pic and post it! More info is required. ------------------
Jay Kilroy
68' Fastback GT 390
"No such thing as a cam thats too big"
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perk
Gearhead Posts: 328
From: Staley,nc
Registered: Sep 2000
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posted 05-09-2001 11:07 PM
Ok,I'm on a buisness trip,but I'll be home
fri.Will get more info and post it fri. PMthanks,perk
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Ryan Wilke
Gearhead Posts: 706
From: Stanton, Michigan
Registered: Oct 2000
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posted 05-11-2001 06:01 PM
Nos351C:
If I'm recalling correctly, I think you are thinking of the shirt-CRACKING problem with Boss 302 OEM pistons...not collapsing.
Ryan
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Mpcoluv
Gearhead Posts: 424
From: Charlotte NC usa
Registered: Apr 2001
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posted 05-12-2001 08:36 AM
My 372C has some piston slap.
This is due however to the machinist boring the block per the Lunati clearence instructions.
Stupid lunati only lists the racing (nitrous) clearences in the instructions.
.006 - .007", not a range of clearences based on application like the old TRW pistons did.
I'm now stuck with the slap unless I get another block, or knurl the skirts of the pistons......
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perk
Gearhead Posts: 328
From: Staley,nc
Registered: Sep 2000
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posted 05-12-2001 10:06 AM
If my timing marks are correct,I have 10 at
the crank And a total of 37 all in at 2700rpm.Will have pictures posted later today of the plugs.
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SteveLaRiviere
Administrator Posts: 23693
From: Saco, Maine USA
Registered: May 99
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posted 05-12-2001 02:25 PM
quote:
Originally posted by Ryan Wilke:
Nos351C:
If I'm recalling correctly, I think you are thinking of the shirt-CRACKING problem with Boss 302 OEM pistons...not collapsing.
Ryan
Yeah, the early '69 Boss 302, right? ------------------
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC {Wife's car...}
All Fords since 1977
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SteveLaRiviere
Administrator Posts: 23693
From: Saco, Maine USA
Registered: May 99
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posted 05-12-2001 02:28 PM
quote:
Originally posted by perk:
If my timing marks are correct,I have 10 at
the crank And a total of 37 all in at 2700rpm.Will have pictures posted later today of the plugs.
An overly lean condition will cause preignition/detonation, too. ------------------
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Loc
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
'97 Probe GTS 2.5L DOHC {Wife's car...}
All Fords since 1977
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n2oMike
Gearhead Posts: 933
From: Spencer, WV
Registered: Jan 2001
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posted 05-13-2001 10:58 PM
quote:
Originally posted by SteveLaRiviere:
Yeah, the early '69 Boss 302, right?
All factory Boss 302 pistons suffered from this. I purchased a "blown-up" 70' Boss 302 engine several years ago that was still standard bore with the factory pistons installed. Guess what... a piston came apart, taking a cylinder wall and rod along with it. The cylinder is being repaired as we speak with a 0.125" wall sleeve. The rod is as crooked as a dog's hind leg! The kicker... the engine had been apart before! Several of the piston skirts had cracks, and someone had tried to stop the cracks by drilling small holes at the ends of the cracks. Guess what... It didn't work!!! The pistons that were still intact, had cracks that spread past the drilled holes, and the one that came apart was DEFINITELY not serviceable. This is a 70' model engine. TRW makes a nice replacement with reinforced piston skirts. Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/motorcitymustang/cmml/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367 [This message has been edited by n2oMike (edited 05-14-2001).]
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