|
|
|
|
| Author |
|
|
Super Moderator
|
Weird pit in head near intake valve
996 GT3 Cup. Looks like a casting flaw. How the &^%^ does this get past quality control?
I'm concerned about it being a potential detonation spot although everything looks fine around it, and there is no mark on the piston that suggests FOD.   
__________________
Chris ---------------------------------------------- 1996 993 RS Replica 2023 KTM 890 Adventure R 1971 Norton 750 Commando Alcon Brake Kits |
||
06-21-2017, 11:35 AM
|
|
|
Registered
Join Date: Feb 2004
Location: UK
Posts: 2,230
|
Have the heads been cleaned up with something like a vapour blaster?
It may not have looked this bad when the head was new and the defect may have been full of a non-metallic. It is possible that the core used to form the ports may have had a small foreign body stuck to its surface.. I would agree that it is undesirable but as it's a hole I would think it is unlikely to generate a 'hot spot' in the same way as if it were sticking out from the surface. You could try to fill it up with a high temperature repair putty which even if it fell out would be unlikely to do much damage. High Temperature Adhesives and Epoxies, Ceramics, Insulation, Epoxies and Epoxy Last edited by chris_seven; 06-21-2017 at 12:39 PM.. |
||
|
06-21-2017, 12:35 PM
|
|
|
Super Moderator
|
Chris - Engine hasn't been opened while in my possession before. It had a full rebuild 80 hours ago, so it may have been. The "pit" may be smaller than it looks with the carbon making it look worse. We'll see.
I think I'll just have it welded and milled back since the engine is getting a refresh anyway.
__________________
Chris ---------------------------------------------- 1996 993 RS Replica 2023 KTM 890 Adventure R 1971 Norton 750 Commando Alcon Brake Kits |
||
|
06-21-2017, 03:13 PM
|
|
|
Registered
Join Date: Jul 2006
Location: S. Florida
Posts: 7,249
|
I think the head would be best off left the way it is. The heat from welding could cause other problems with the head and the valve seat could be damaged and need to be replaced etc.
The pit will eventually fill up with carbon deposits if you're using gasoline instead of E85 and will probably be harmless. |
||
|
06-24-2017, 08:41 AM
|
|
|
Registered
Join Date: May 2005
Location: Loxahatchee, florida
Posts: 2,894
|
if you do decide to get it welded the guys at Xtreem cylinder heads do that. They will weld it then remachine it. Theyu filled in the Injector Notch in mine when i had them done and there were several sets of heads in the shop for welding repairs.
__________________
88 turbo Guards red Targa slant nose, and yes I am a horsepower junkie, 3.4liter,7.5 to 1 JE pistons, Adjustable WUR, Imagine fuel head, 1 bar waste gate headers,allthe cis toys. Now apart to become the next EFI monster. fabbing my own intake, headers Individual throttle bodies, MS-3, pauter rods, Xtreme twin plugged heads, gt-2 evo cams cop's. 2019 Silverado 6.2L |
||
|
06-26-2017, 08:06 AM
|
|
|
Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,141
|
TIG only if you're going to repair IMO. That would keep the heat localized as possible.
The most blunted tip for the narrowest arc.
__________________
Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel |
||
|
06-26-2017, 08:16 AM
|
|
|
|
Super Moderator
|
I think what I will do is use a high-temp crack filler to lessen the size. If it drops out it won't harm anything. It was fine for 11,000 km so probably fine to monitor it via boroscope.
__________________
Chris ---------------------------------------------- 1996 993 RS Replica 2023 KTM 890 Adventure R 1971 Norton 750 Commando Alcon Brake Kits |
||
|
06-26-2017, 11:28 AM
|
|
1970 Porsche 911 S 
