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Super Moderator
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Help needed... Major flat spot/power loss in rev range
I'm posting this question for a guy I work with who is stumped...
Motor: 3.2L 46mm Webers Venturis and Jets as recommended by PMO Electromotive ignition (5 deg idle, 30 degree@3000rpm, 25 degrees@7000RPM) Twin plugs, Max Moritz pistons (9.8:1)... Problem: At above 3000RPM car just bogs majorly, engine goes BLAHHHHH and makes no power. Not experienced with no load, just when car is moving... THis may not be enough info, but if you need anything else, let me know.... THanks
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Chris ---------------------------------------------- 1996 993 RS Replica 2023 KTM 890 Adventure R 1971 Norton 750 Commando Alcon Brake Kits |
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07-01-2002, 07:19 AM
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Senior Member
Join Date: Feb 2000
Location: Lacey, WA. USA
Posts: 25,309
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Are you saying it has less advance at 7000 rpm than at 3000 rpm? Carburetors are kind of foolproof in some ways, and this does not sound like a carb problem. I'd guess ignition, or perhaps the fuel pump is not delivering sufficient volume. As a quick test (I imagine Porsches are the same as other cars), the fuel pump should be able to fill a pop bottle in about 40 seconds.
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Man of Carbon Fiber (stronger than steel) Mocha 1978 911SC. "Coco" |
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07-01-2002, 07:24 AM
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Registered
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Chris,
I'm having the same problem with my engine: it just doesn't want to rev past 4,000rpm, under load. My mechanic has tried everything: another MFI pump; another ignition system; another coil; another distributor; new spark plugs and new injectors. No change. He even performed a compression test -- 210 for every cylinder. He's baffled, and he's got 40 years experience with Porsches. Before I had the distributor modified I had the Marchal alternator rebuilt and the voltage regulator replaced. My mechanic didn't check these components in the initial elimination round, but when I suggested it, he got excited as the only thing left to check is the valve timing, and he can't see how it could be that given the fact that it's behaving perfectly under 4,000rpm ... Matt Holcomb MFIWDP 1974 911 Carrera 2.7 RoW 1975 Mercedes-Benz 280SE Dedicated Homepage Engine Rebuild Homepage Porsche Owners Gallery Profile Pelican Gallery Profile |
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07-01-2002, 07:46 AM
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Super Moderator
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...turns out it was the timing wheel on the electromotive...
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Chris ---------------------------------------------- 1996 993 RS Replica 2023 KTM 890 Adventure R 1971 Norton 750 Commando Alcon Brake Kits |
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07-01-2002, 08:35 AM
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1970 Porsche 911 S 
1974 Porsche 911 Carrera 2.7 2.7 MFI
