The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 08-31-2019, 05:27 PM   #1
ric812
Registered User
 
Join Date: Mar 2010
Location: Clarksville, TN
Posts: 15
Piston damage question

I just traded a motorcycle for a SBC engine. The #1 piston on shows signs of hitting a valve.
My question is do I need to replace it or can I smooth it out some? I have never had an engine with this type of damage. The Pistons are 2244P TRW. I believe they are forged. I am planning on rebuilding the engine. Any help would be great.
Attached Images
 
ric812 is offline   Reply With Quote
Old 09-01-2019, 08:32 PM   #2
AussieinNC
Senior Member
 
AussieinNC's Avatar
 
Join Date: Jun 2017
Location: Cherryville, NC
Posts: 1,113
Re: Piston damage question

Others will chime in I am sure...but here is my 2 cents worth....

What is the engine supposed to be? 350? 327? 307?

Throw that piston away, its junk....

The head that was on that side will need to be carefully checked for vale damage and valve stem wear....

You should also check the cam and lifter associated with the failed cylinder
__________________
Family and country before all others...
1968 C-10 SWB
1974 C-10 Longbed
2001 GMC Sierra
2006 Chevy Silverado (Daily Driver)
AussieinNC is offline   Reply With Quote
Old 09-01-2019, 10:49 PM   #3
ric812
Registered User
 
Join Date: Mar 2010
Location: Clarksville, TN
Posts: 15
Re: Piston damage question

It is a 350 bored 40 over. I don't have the heads or the lifters. And the cam is being replaced. Thank you for the information.
ric812 is offline   Reply With Quote
Old 09-01-2019, 11:44 PM   #4
Dead Parrot
Registered User
 
Join Date: Aug 2012
Location: Oklahoma City, OK
Posts: 1,311
Re: Piston damage question

IMO - replacing that piston is the best solution. If budget is an issue, can always try a gentle dremel type smoothing. Just accept the risk of the piston face having a flaw that might cause another engine rebuild. Inspect the rod, rod bearings and crank bearings on that cylinder as well. They also took a hit.
Dead Parrot is offline   Reply With Quote
Old 09-02-2019, 03:09 PM   #5
AussieinNC
Senior Member
 
AussieinNC's Avatar
 
Join Date: Jun 2017
Location: Cherryville, NC
Posts: 1,113
Re: Piston damage question

That piston damage has been caused by the engine swallowing a metallic object...

When an object thicker than the deck clearance is swallowed, it will and does cause the piston to be subjected to excessive stresses.

The piston is most likely cracked through the pin journal area or the skirt area....

A 350 that is already plus 040 has one rebore left...up to .060 over, without going to special size pistons...= more dollars....

However, the cylinder walls get very thin at .060 over....

Is this engine a roller cam engine or a flat tappet cam engine?

Is the engine a 4 bolt main or 2 bolt main ?

What is you expected use for the engine?

Have you removed the piston and rod and checked the cylinder walls for damage?

If its a flat tappet, 2 bolt 350 already at +0.040....it has a future as a street engine...others may disagree, but after building well over 300 of these small blocks over 35 years, you tend to have an informed perspective.

I hope that bike you traded was a el cheapo...if its a 2 bolt 040 over 350, its worth $150 max, especially with a damaged hole...

__________________
Family and country before all others...
1968 C-10 SWB
1974 C-10 Longbed
2001 GMC Sierra
2006 Chevy Silverado (Daily Driver)
AussieinNC is offline   Reply With Quote
Old 09-03-2019, 11:10 AM   #6
JMac11
Registered User
 
JMac11's Avatar
 
Join Date: May 2005
Location: Tallahassee Fl
Posts: 707
Re: Piston damage question

My 2 cents, but if the wrist pin is free and the ring grooves aren't collapsed, run a file across the top of the piston to remove the sharp edges and put it back together. The marks on the piston are that of a exhaust valve stuck open, broken spring or retainer. To each his own
JMac11 is offline   Reply With Quote
Old 09-03-2019, 12:32 PM   #7
BigBird05
Registered User
 
Join Date: Aug 2019
Location: Cheraw
Posts: 58
Re: Piston damage question

You need to pull, examine and or replace that piston. You will need to examine the cylinder bore for any damage. I would replace that piston and not trust it. I also have built 200 plus engines and seen some blow up after a cheap rebuild. Trying to save money usually costs more money.
BigBird05 is offline   Reply With Quote
Old 09-03-2019, 01:14 PM   #8
DieselSJ
Registered User
 
Join Date: Jun 2016
Location: Phoenix, AZ
Posts: 513
Re: Piston damage question

Quote:
Originally Posted by BigBird05 View Post
You need to pull, examine and or replace that piston. You will need to examine the cylinder bore for any damage. I would replace that piston and not trust it. I also have built 200 plus engines and seen some blow up after a cheap rebuild. Trying to save money usually costs more money.
^^This^^
__________________
87 R30 CC Dually, TBI 454, NV4500, zero rust barn find
87 Jeep Grand Wagoneer, 6.5 turbodiesel, 700R4
DieselSJ is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 02:39 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Copyright 1997-2013 67-72chevytrucks.com