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blackhat · Posted: Mon Apr 28, 2008 2:05 pm Post subject: Head gasket/head rebuild?

Hey all,

You've probably seen me asking tons of questions about the head gasket and heads. This will be my first major repair job on a vehicle so I'm trying to soak in all the info I can before I undertake it.

My question to you all is, since the head is going to be off and I don't know when the last rebuild was, should I do a valve train rebuild?

I'm not entirely sure what all it entails. Is this something where if I bought the new springs, valve guides, and valves, I could just throw them in? I've heard talk about having to grind the valves down to match a specific height. Is this something more than a micrometer and a Dremel? Is this something a machine shop could do for cheap?

I figured I could look into it since the head will be off and the valves will be out for the valve seals.

Any thoughts and advice would be great!
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My First Porsche
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1978 Porsche 924 N/A

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

I haven't paid for a "carry-in" valve job in a while, but last time I did it was quite cheap at the machine shop. Probably not a job you want to cut your teeth on without supervision!
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Buwani 931 · Joined: 31 May 2004 Posts: 308 Location: Napa California

The key is finding a good machine shop. They will be able to tell the condition of the springs , guides , straigtness ect. Grinding or lapping the valves and seats is common and not expensive. No need replacing parts that still have life.
Ask around, find a shop that does good honest work and you are set.

Shawn
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1980 931
That's thirty minutes away. I'll be there in ten.

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

if the valves aren't bent, they can be cleaned. If they have some minor damage on the sealing surface, they can be machined, making the seal like new.

If that should occur, the valve seats (which are the most common 'repair') should be taken care of. That just involves cutting the seats, which causes the valve to sit deeper in the head, so the valve stem needs to be shortened too.

The guides could be worn out, those are hard to get over here, but maybe in the US it's not a problem. Won't take much time, so costs less

If the valve seats are damaged too much to cut them, they need to be replaced. The material costs are low on that.

After all that work has been done, the head gets flattened (how do you call that?) so that the gasket won't leak.

Most of the costs is in labor, material isn't that much.

Just find a rebuilding shop which takes a look at the head and can specify what needs to be done. In most cases, all mentioned above is NOT necessary. If the valves seal the ports well (vacuum test) there is no need to clean the valves, cut the seats and so on...

Luckily it's an 8valve head... 16v costs way more

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"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment

blackhat · Posted: Mon Apr 28, 2008 8:50 pm Post subject:

Awesome! Thanks for the advice! I'll be calling the machine shops today and some various auto guys to see if they would suggest one.
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My First Porsche
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1978 Porsche 924 N/A

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

I'm with Dan. Call Jorge at European Motorworks, then pack up your head with a $1000 bill and have them go to work on it. They've been tuning these cars since the 1980s when they were called Euro Race. Best money you'll spend on a normally aspirated 924 engine is the big valve head conversion, trust me.
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1987 951 - M193 Version for Japan

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

If you are close to Tulsa, OK Gary Robinson knows Porsche heads and he is very reasonably priced. I've used him for both the 928 and 924 heads and it's never cost more than $200 for a rebuild. If interested, let me know and I'll get his phone number for you.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

924er · Posted: Thu May 01, 2008 5:14 pm Post subject:

i dont know shit about cars so.....

i recently did a rebuild on my head and i had a bent valve, blown head gasket, i mean it was crazy in there!

i had this mexican mechanic who took my head out and took it to a machine shop and came back and installed it in about a week, took another weak to tune that #### and find all the leaks but we finaly finished today and all it costed was $850 TOTAL including labor... i was pretty impressed

still slow is fuk.... a bit faster tho a mom with all her soccerr team kids in her van would probably beat me but i still love my 924 and ive owned several cars but i will never sell this one!
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80' Porsche 924 NA - Slower then a S L O W
86' Porsche 951- New toy