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HMeeder's Avatar
 
Join Date: Sep 2000
Location: San Diego, CA, USA
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Porsche Crest Lunched a Valve

My car decided to eat one of its own at Sunday's Time Trial. Car ran great all weekend (the course was murder on brakes and cars. By the time AAA removed me 7 cars had already been towed away, and the Timed Runs hadn't even begun!)

Valve head snapped off its shaft on #4 cylinder and bounced around inside for about 10 seconds before I could get to the ignition (on the warm up lap no less!) This is what the plug looks like and staring down inside the hole reveals what appears to be grey oatmeal. At least the bottom end should still be fine (I'm hoping.)
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File Type: jpg busted plug.jpg (19.9 KB, 259 views)
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Herb
'72 Tangerine 'Teen
2.4 liter aluminum handgrenade
Old 11-26-2002, 11:04 AM
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Unhappy

That sucks. Why did this happen? (Iknow, the $1million dollar question...) Did it get too hot?
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Old 11-26-2002, 11:06 AM
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Knowing how fast Herb drives ( I was his instructor once), even on warmup laps, I'll bet the valve floated since his valve train is stock (if I remember correctly) and has some milage on it. You might say, a valve can't float at 5000 RPM or less, but they sure can especially with worn valve train parts and single springs, etc. We fought the valve breaking problem for two years before solving it finally. Of course it could just be metal failure too? If there are no holes though the piston you might not have to split the case, but that might be the way to go anyways? Good luck.
Old 11-26-2002, 12:11 PM
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Porsche Crest I'm guessing John is right

Presently it appears that the case is intact. There's nothing in the oil, but until I get the head off, I won't be able to tell whether the piston got a hole punched in it or not.

Jess Osterberg has a 1.7 long block and several sets of heads that he had been trying to sell me for a while. I'm thinking I may get the motor and install it in order to get the car back on the street (it is my daily driver) and then rebuild the other case (new jugs and rebuild a set of heads) for further down the road.

ps John, congrats on your win at Pheonix. I see from the SDR website that Ted lunched a motor too. Expensive weekend for the club. One guy from, I think Grand Prix, tossed a rod through the block of his 928 and I was trailing a 944 turbo when it went south in a fightening and magnificent cloud of blue smoke. Many other lesser problems, but hard times indeed.
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'72 Tangerine 'Teen
2.4 liter aluminum handgrenade
Old 11-26-2002, 12:55 PM
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I went to HSR West at PIR on Sat. and had a blast. The 914s were blowing the doors off some of the 911s and everything else... it was amazing.

It was also a major rush to see the Porsche 910 litterally outpace every car on thefield leaving the larger motored cars well behind it... truly a magnificent machine.

Sorry to see the yellow 914 get bent near the finish... I hope the driver is well and the car is repairable.

I met some great people and only wished I had been fortunate enough to speak with some of the Porsche drivers.

You guys made my weekend!
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Old 11-26-2002, 01:04 PM
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So, what are some thing a person could do to a stock valve train to prevent something like this? Where does the problem start?Im a bit ignorant on the whole dropped seat, rod thing , but I want to become educated.
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Old 11-26-2002, 01:20 PM
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Thats what kills these engines, over and over,,what was the story on the engine, how many miles? HP rating, stock?? exhaust valve, if so was it sodium filled?

Expect absolutely the worst, don't trust the rod or the crank, as I have had failures not show up in magnaflux that showed up 18,000 miles later on my own crankshaft that dropped a valve at 6,000 in the burnout box with a TIV powered beetle.

3 weeks ago my girlfriend absolutely destroyed a comple 2.0 in my tired old 914 running 90MPH in 5th. the only salvageable parts were one cylinder and one head, and the hardware, the esle was history, see my pics here

http://aircooledtechnology.com/jake/914/lost-valve.html

don't get your hopes up, but we can repair the head, thats sometimes the easy part.....I was proud that she killed mine, I had been trying to for 7 months!
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Old 11-26-2002, 01:21 PM
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For Brian, I hope I got to say hi on sat as several people stopped by to look at the only 914- 4 in the race but it goes pretty well I think. I found I could not run flat out on the turns 3 & 4 as some did because the car was too stiff, being setup for the turns. PIR has more oval than turns it appears so next year I will use some 200# rear springs (not the 300#) and soften the front sway bar. Herb, once you get the engine opened, take the broken parts to the well know race shops we are lucky enough to have in SD and get several opinions on what to do, then think a while and make the decision and fix it. You can save the heads no matter how bad as Tuttle's in LA have fixed mine and they do heat treatment, etc after the repairs and also know how to put in the seats well. While you're at it, this might be a gooood time to learn how to do a port and polish on the ports as the heads can sure use help. Stainless valve, dual springs, titanium retainers and CroMo racing push rods all will help make some more power and make it much more reliable. Keep us posted.
Old 11-26-2002, 02:11 PM
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HMeeder,

If you don't mind my prying.... was it a FI motor or a carbed motor...?


I'm developing a great big ohhh soo... scientific theory about valves and seats... with relation to air/fuel ratio and head temp...

brant

Last edited by Brant; 11-27-2002 at 07:52 AM..
Old 11-27-2002, 07:09 AM
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Porsche Crest FI Stock

Other than exhaust and a K&N filter, the motor was bone cold stock.

Ultimately I get the feeling that John is right. High revs and temps (though the car topped at only 210 degrees) probably caused the valves to 'float'. I think the exhaust valve didn't return to its seat in time to get its head slapped by the piston.

Thanks to all for your your thoughts and help. James (Red Beard) has a motor for me and I've received many phone calls and e-mails from people that have offered parts.

This community is awesome!
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Herb
'72 Tangerine 'Teen
2.4 liter aluminum handgrenade
Old 11-27-2002, 07:56 AM
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Time to build that stroker motor huh Herb?????
Old 11-27-2002, 08:16 AM
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