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Registered
Join Date: Apr 1999
Location: Newbury Park, CA 91320
Posts: 1,523
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993 heads
guys - I have a few 993 heads and noticed (1) has cracked and missing chunks of ceramic liner in the exhaust port. Can this be fixed? How to fix it? It looks like 35% of the liner is missing? Is there a high temp epoxy to fill in and build up to repair? Open to thoughts, suggestions and possible solutions from the group. Thanks! Jim Dorociak
jdorociak@gmail.com |
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01-17-2023, 04:22 PM
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They crack... I've only seen 3-4 3.6 engines apart but all had cracks and missing parts of the liner. My engine is missing some of its liner.
Probably not ideal, 35% seems like a lot, but I wouldn't worry unless you have a turbo. The common method of repair I think is to replace the head with a better one.
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Magnus 911 Silver Targa -77, 3.2 -84 with custom ITBs and EFI. 911T Coupe -69, 3.6, G50, "RSR", track day. 924 -79 Rat Rod EFI/Turbo 375whp@1.85bar. 931 -79 under total restoration. |
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01-18-2023, 11:10 PM
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Registered
Join Date: Jul 2013
Location: Brisbane, Australia.
Posts: 2,602
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Always learning. www.aircooledporsches.com.au See me bumble my way through my first EFI and TURBO conversion! https://youtu.be/bpPWLH1hhgo?si=GufVhpk_80N4K4RP |
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01-25-2023, 12:53 AM
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Registered
Join Date: Apr 1999
Location: Newbury Park, CA 91320
Posts: 1,523
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Thanks Mike - I sent him a PM and will do a search as well. Jim
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01-25-2023, 09:58 AM
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Racer
Join Date: Oct 2010
Location: Franklin, TN
Posts: 5,885
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This is why I went with Xtreme heads for my race engine. Yes, Xtreme heads are expensive, but, for my situation, I will save money in the long run not having to deal with damaged ceramic inserts or cracked heads.
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Scott Winders PCA GT3 #3 2021 & 2022 PCA GT3 National Champion 2021 & 2022 PCA West Coast Series GT3 Champion |
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01-25-2023, 11:16 AM
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Registered
Join Date: Apr 1999
Location: Newbury Park, CA 91320
Posts: 1,523
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Thanks Scott. Not making a race engine, but a solid street engine. Is there any repair that can be done to "fix" the missing pieces of ceramic? I have to assume everyone who had missing ceramic did not throw those heads away. Jim
Last edited by Jim Dorociak; 01-28-2023 at 11:31 AM.. |
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01-25-2023, 01:09 PM
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It's a 914 ...
Join Date: Jan 2008
Location: Ossining, NY
Posts: 4,703
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I've heard several shops mention here and elsewhere that they have repair procedures for damaged ceramic inserts. At least one mentioned an epoxy substance.
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01-25-2023, 01:33 PM
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PCA Member since 1988
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I can't see how any epoxy based material would hold up to the heat in the exhaust port--that's why they are made of ceramic in the first place. Whatever they brushed into the exhaust port must be a ceramic based thermal barrier coating (TBC), that must be heat cured in an oven first, then finish cured by running the engine. See one of your local TBC specialists. FYI, I had TBC applied to the exhaust ports of my engine I built a year ago. So far, so good (6000 miles).
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1973.5 911T with RoW 1980 SC CIS stroked to 3.2, 10:1 Mahle Sport p/c's, TBC exhaust ports, M1 cams, SSI's. RSR bushings & adj spring plates, Koni Sports, 21/26mm T-bars, stock swaybars, 16x7 Fuchs w Michelin Pilot Sport A/S 3+, 205/55-16 at all 4 corners. Cars are for driving. If you want art, get something you can hang on the wall! |
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01-28-2023, 10:12 AM
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Join Date: Oct 2012
Location: Peoria, Arizona and Big Rock, IL
Posts: 296
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If the ports want to be bigger, then why fight them? (sarcasm, haha, not really a question)
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07 911 Turbo - Pilot Sport Cup 2 ZP 96 Carrera 4 - Toyo R888r 73 911E - Hoosier R7 + twin 75's 92 Corvette - Nitto NT01 14 BMW X3 - Pilot Sport A/S 4 |
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01-30-2023, 02:28 PM
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PCA Member since 1988
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"Be the port."
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1973.5 911T with RoW 1980 SC CIS stroked to 3.2, 10:1 Mahle Sport p/c's, TBC exhaust ports, M1 cams, SSI's. RSR bushings & adj spring plates, Koni Sports, 21/26mm T-bars, stock swaybars, 16x7 Fuchs w Michelin Pilot Sport A/S 3+, 205/55-16 at all 4 corners. Cars are for driving. If you want art, get something you can hang on the wall! |
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01-30-2023, 10:00 PM
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Join Date: Jun 2013
Posts: 491
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07-15-2023, 06:19 PM
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PCA Member since 1988
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Nope. TBC's will reduce head temps. How much, and whether it makes a difference in the longevity of the heads is an open question.
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1973.5 911T with RoW 1980 SC CIS stroked to 3.2, 10:1 Mahle Sport p/c's, TBC exhaust ports, M1 cams, SSI's. RSR bushings & adj spring plates, Koni Sports, 21/26mm T-bars, stock swaybars, 16x7 Fuchs w Michelin Pilot Sport A/S 3+, 205/55-16 at all 4 corners. Cars are for driving. If you want art, get something you can hang on the wall! |
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07-16-2023, 02:36 PM
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I use cerakote thermal barrier on 356 exhaust/heads/valves piston top, super durable. Prep is key:
- ultrasonic clean -heat up head to 300 to bring up any oil left over -ultrasonic clean again - blasting with aluminum oxyde - ultrasonic clean - dry - spray cerakote - cook for 1hr at 300 |
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07-16-2023, 04:21 PM
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1977 Porsche 911 Targa 2.7s
Brown bunny
Le Mackerel
