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Old 04-25-2008, 11:21 PM   #1
MUSTANG ROBERT
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Default 351cleveland 4v lack of power help please

hi guys,
i just built a 351 cleveland 4v heads. has 10.0 to 1 speed pro, isky solid 530 lift and 278 duration cam, 1.75 roller rockers, screw in studs, manley valves, dual springs, new water oil and fuel pump, milodon 9 quart oil pan, 4150 double pump holley, pertronics coil and chip in distributor.

this motor is going in my 1971 mach 1, all part are new and its a 4 speed manuel

so heres the problem, broke in the motor at 2,000 rpms for 20 mins. i have about 20 miles on motor. got fuel and spark, timing at 12 idel and 37 max. around 3,000 the motor backfires. the motor hesates when yourev it and theres no power at all.pulled the plugs and all dry black carbon, drove about 4 to 5 miles and used up 1\4 of a tank about 4 gallons

WHATS wrong with my mach1. any thoughts are appreciated
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Old 04-26-2008, 05:11 AM   #2
9 Sec 93 LX
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Default RE: 351cleveland 4v lack of power help please

Quote:
ORIGINAL: MUSTANG ROBERT

hi guys,
i just built a 351 cleveland 4v heads. has 10.0 to 1 speed pro, isky solid 530 lift and 278 duration cam, 1.75 roller rockers, screw in studs, manley valves, dual springs, new water oil and fuel pump, milodon 9 quart oil pan, 4150 double pump holley, pertronics coil and chip in distributor.

this motor is going in my 1971 mach 1, all part are new and its a 4 speed manuel

so heres the problem, broke in the motor at 2,000 rpms for 20 mins. i have about 20 miles on motor. got fuel and spark, timing at 12 idel and 37 max. around 3,000 the motor backfires. the motor hesates when yourev it and theres no power at all.pulled the plugs and all dry black carbon, drove about 4 to 5 miles and used up 1\4 of a tank about 4 gallons

WHATS wrong with my mach1. any thoughts are appreciated
What's your fuel pressure? Holley's need 5 to 7 lbs. MAX. More than 7 will over power the float and make it flood. With the aircleaner off and the fuel pump running/engine idling, does fuel leak/spew out of the venturis or vents.Look down into the carb, any dripping or leaking is unacceptable.
If you fuel pressure is okay, it could be a float adjustment.
Or a piece of crap stuck in the needle valve(very common on new installs).
You do have a fuel filter right.
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Old 04-27-2008, 09:54 PM   #3
immr.mustang
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Default RE: 351cleveland 4v lack of power help please

too rich, or you wiped out the cam already man.
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Old 04-28-2008, 04:36 PM   #4
MUSTANG ROBERT
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Default RE: 351cleveland 4v lack of power help please

yeah i do have a filter. the carb is 4150 hp series 750 brand new out of the box only ajusted idle. i planned to put a inline pressure gauge but i forgot i had it and already cut and installed my steal braided lines.
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