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not quite sure but it looks like a mix of cam bolts on that engine, might be a result of the cam grind and I think the chain box nuts should be plain nuts not nylocks. I could be wrong. But it for sure slipped. And the left tentioner is out almost all the way.
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08 Cayenne Turbo Last edited by James Brown; 04-21-2010 at 11:01 PM.. |
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04-21-2010, 10:57 PM
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Somatic Negative Optimist
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danielt:
Quote: "Current condition of the car: Big bore 3.2L cams reground to 964 profile" Big bore 3.2L? Is the engine a '78-'79 with 98mm P/C's? Carefully check the cam-timing again. I set the timing for my 964-cams to 1.4 mm (SS 3.2 - 98 mm P/C's with CIS) Check/compress the tensioners to see if they're good. If the chain jumped, the pistons would have touched the valves; not good. That may explain the lower compression on that side? Both cams show the large 47 mm nut but: why does one cam have a center bolt and the other doesn't? Worsed scenario: If in the past a new chaine was fed onto old chain sprockets (on the I-shaft), you might find the teeth from those sprockets in the sump screen meaning: the chain may have jumped.
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1980 Carrerarized SC with SS 3.2, LSD & Extras. SOLD! 1995 seafoam-green 993 C2, LSD, Sport seats.  Abstract Darwin Ipso Facto: "Life is evolutionary random and has no meaning as evidenced by 7 Billion paranoid talking monkeys with super-inflated egos and matching vanity worshipping illusionary Gods and Saviors ". 
Last edited by Gunter; 04-22-2010 at 08:25 AM.. |
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04-22-2010, 08:23 AM
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Gunter,
Yes, it is an 1981 with 98mm P/Cs. I did not know the 964 cams had a different timing spec when I originally setup in the engine and used the stock SC spec of 0.9-1.1mm. I can't answer the center bolt question. It was like that when I originally tore the engine apart. I have not found any parts in teh screener yet. I'll try and get a mirror in to inspect the intermediate shaft. Thanks for the feedback Gunter!
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Daniel Tisserand 1981 SC 3.2L short stroke |
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04-22-2010, 10:09 AM
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Somatic Negative Optimist
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SC's had different stock cam timings:
930/04 = 0.9 - 1.1 mm 930/07 or 930/16 = 1.4 - 1.7 mm Your '81 would be 1.4 - 1.7 mm for stock cams, IMHO. 1.4 mm for a 964 profile was recommended to me by a few experts and I am very happy with that. Re-time carefully going around three times.  You can actully see one chain sprocket through the sump opening with a light and mirror on the I-shaft on either side of the larger drive gear.
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1980 Carrerarized SC with SS 3.2, LSD & Extras. SOLD! 1995 seafoam-green 993 C2, LSD, Sport seats. Abstract Darwin Ipso Facto: "Life is evolutionary random and has no meaning as evidenced by 7 Billion paranoid talking monkeys with super-inflated egos and matching vanity worshipping illusionary Gods and Saviors ".
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04-23-2010, 08:10 AM
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Victory is mine!!!
I finally determined root cause. The cam adjustment flange behind the cam sprocket sheared off 2 teeth. I did not replace it when I rebuilt the motor and it either fatigued or I didn't have the nut properly torqued. I'll post pics as soon as I get it disassembled. Not pretty, but glad I found why the timing was off... finally! Only been working this on and off for 3 years...
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Daniel Tisserand 1981 SC 3.2L short stroke |
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05-22-2010, 07:08 PM
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 Well, here is the broken cam adjuster. New ones on order from Pelican.
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Daniel Tisserand 1981 SC 3.2L short stroke |
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05-24-2010, 05:38 PM
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ME 262 (SOLD)
Colibri
Gas Mizer
Mileage King
Dog Bus
1981 Porsche 911SC 3.2L Short Stroke
