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Rebuilt engine but runs crappy, help??
Hello fellow pelicanites, i recently had my engines rebuilt according to Dempseys high compr. chart....I replaced my stock pistons with je 9:8:1 and changed my cylinders to mahle and had everything rebuilt after cylinders and had 964 cams installed....I had the engine put together by a experienced mechanic and i replaced the fuel system and exhaust and installed the engine.. My engine is an 83sc and the engine runs fine in the garage but hesitates underload and im almost sure the timing is right and ive tried to adjusted the fuel distributor countless times.....Guess my next question is what is the correct fuel pressure for a stock engine like mine and what would be the correct for psi for my new engine?? Should it be more now??
Could my f-distributor be clogged, if my f-pressure is low? Please any inquires are welcome.....damian ps...starts up quick and runs good in garage.... |
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10-30-2006, 09:33 AM
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Have you checked the fuel pressure and timing?
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2014 Cayman S (track rat w/GT4 suspension) 1979 930 (475 rwhp at 0.95 bar) |
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10-30-2006, 11:08 AM
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Location: Miami
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Did you have a rusty tank? Rust is the root of all evil.....
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1975 911 Carrera BLK/BLK |
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10-30-2006, 11:25 AM
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Location: Lexington, SC
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"almost sure the timing is right"
Almost? |
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10-30-2006, 11:50 AM
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Location: Chalfont Pa
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where are you located?
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10-30-2006, 12:01 PM
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Hello Ya'll haaaa, that tell u im in Houston texas??
Well as far as rust or bad gas im at the present draining the gas tank right now because when i took the filter off i could of sworn the gas was a little redish...?????!!!! Im almost positive the timing is right and possibly the fuel distributor is probably close enough....AS far as the fuel pressure no i do not have the gauges for that , thats what maybe worries me.... |
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10-31-2006, 09:19 AM
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Damian - I wondered how this was going. Sorry you're not on the road yet. If you don't have a Bentley for that car it would be a big help to trouble shoot the fuel injection. Assume you're going to replace the fuel filter. Give me a yell if I can help. Ken
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10-31-2006, 09:39 AM
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Where in Houston are you?
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2014 Cayman S (track rat w/GT4 suspension) 1979 930 (475 rwhp at 0.95 bar) |
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10-31-2006, 09:43 AM
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Hey Ken how are you, no not on the long road yet just the short roads behind my house because it starts to run like crap after about 1 mile...
125- i live on the northside of the bush airport, 1960, i know total opposite of u....I need to purchase the bentley book and some gauges in the near future, propably should of had them already ken huh, right after we took the engine out..?, didnt know i was going to run into another problem.... I just took out 3 gallons of gas from tank and replaced it with new 93 octane of 15 gallons, and yupp just what i thought didnt make a difference..... 125 or Ken do yall know anything about fuel pressures ?? |
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10-31-2006, 10:10 AM
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Damian911,
Did you check the fuel filter for metal flakes? If you have a rusty tank this could be a culprit. Also try disconnecting the vacum hose on the WUR and plugging it. Aggresive cams create alot of vacum and lean out the motor.
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1975 911 Carrera BLK/BLK |
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10-31-2006, 10:31 AM
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Carreric ill check the filter closely but do not think i saw anything earlier....Ill also try plugging that hose too...thks
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10-31-2006, 10:37 AM
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You are experiencing the same problem I had after SC grind installed on my 2.7L.
.1) I had a rusty fuel tank that kept contaminating my system. I replaced everything with "new" parts in my fuel system WUR, FD, Injectors, Fuel Pump, etc etc . Thousnads of $$$$$. The only way to solve this problem is a new tank or have TANK RENU refurbish it. 2.) My cams created mor vacum than the stock. When the car was at idle it ran perfect. But under load the engine would lean out completely causing it to stumble, heitate and run rough. Plugging the vacum line on the WUR solved this problem. You can varify this on a C/O analyzer. Good luck with the car. Hope it helps......
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1975 911 Carrera BLK/BLK |
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10-31-2006, 10:53 AM
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Carreric....nope i wish it would of been that easy but it didnt work for me....car was running way to bad for it to be as easy as a line, in my opinion....
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10-31-2006, 10:26 PM
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I've got the gauges and books, but of course I'm on the other side the town probably 40 miles away. If I wasn't pulling my own hair out trying to get my EFI to work, I'd make the trek up there.
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2014 Cayman S (track rat w/GT4 suspension) 1979 930 (475 rwhp at 0.95 bar) |
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11-01-2006, 04:46 AM
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Designer King
Join Date: Mar 2004
Location: Toronto, ON Canada
Posts: 5,499
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Ditto on control pressures. When I changed from my low comp 2.7 to my high comp 3.2 I had to "knock the plug" to achieve correct driveability. System fuel pressure was kept stock (65-75 psi). I've yet to measure my control pressures so I can't give you a figure. I just adjusted til it ran right.
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Paul Yellow 77 Sunroof Coupe/cork interior; 3.2L SS '80 engine/10.3:1/No O2; Carrera Tensioners; 11 Blade Fan; Turbo tie rods; Bilstein B6; 28 tube Cooler; SSI, Dansk; MSD/Blaster; 16x7" Fuchs/205/50 Firestone Firehawk Indy 500s; PCA/UCR, MID9 Never leave well enough alone |
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11-01-2006, 06:05 AM
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ok thks guys...guess im going to just have to take it in and have it professionly diagnosed
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11-01-2006, 07:24 AM
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1979 Porsche 930 3.4
